Systems and methods for integrating a water heating unit and a heat pump

Abstract

An integrated heat pump-water heater system includes a heat pump with a refrigerant loop. The system also includes indoor and outdoor heat exchangers, a water heater with a water loop and a water-refrigerant heat exchanger (WRHX) thermally connecting the water and refrigerant, and a controller. In space heating mode, the controller assesses if water can heat the refrigerant; if so, it directs water to the WRHX and routes refrigerant through it. When an ambient condition is met and water is available, the controller directs refrigerant to flow between the WRHX and indoor heat exchanger, bypassing the outdoor heat exchanger, with the WRHX heating the refrigerant. If the ambient condition is unmet or water is unavailable, the controller directs refrigerant to flow between the indoor and outdoor heat exchangers, with the outdoor heat exchanger heating the refrigerant.

Description

FIELD

[0001] The field relates generally to air conditioning and hot water supply systems and methods, and more particularly, to systems and methods that enable integrating a water heating unit with a heat pump.BACKGROUND

[0002] Heat pumps are used in heating, ventilation, and air conditioning (HVAC) and refrigeration systems to control the temperature and humidity of an air stream provided to an indoor space (e.g., a building). Upper and lower temperature limits may be specified by an occupant or owner of the building, such as an employee working in the building or a homeowner. A thermostat controls operation of the heat pump based on a comparison of a measured temperature of the air stream and a target value. For example, the thermostat controls the heat pump to heat the air stream provided to the indoor space when the air temperature is less than the lower temperature limit, and the thermostat controls the heat pump to cool the air stream provided to the indoor space when the air temperature is greater than the upper temperature limit.

[0003] Known heat pumps used in HVAC and refrigeration systems include an outdoor unit having a compressor and an outdoor heat exchanger for rejecting heat into or absorbing heat from ambient air, and an indoor unit connected to the outdoor unit and including an indoor heat exchanger for absorbing heat from or rejecting heat into the air stream provided to the indoor space. A working fluid (e.g., refrigerant) is circulated in a loop between the indoor and outdoor heat exchangers (e.g., via the compressor) and undergoes phase changes that enable the heat absorption and heat rejection processes to take place in the respective heat exchangers.

[0004] Systems have been proposed that combine the working fluid loop of a heat pump with a water loop of a water heating unit. In some systems, the working fluid loop and the water loop are thermally connected by a refrigerant-water heat exchanger that enables the refrigerant to reject excess heat from the working fluid loop to provide supplemental heating of water in the water loop. The heated water can then be recirculated to a hot water tank, which also includes a primary heat source that heats the water inside the tank. The hot water inside the tank can then be supplied to various areas of the indoor space, such as a kitchen, bathroom, and the like. Providing supplemental heating from the heat pump to the water heating unit can reduce a load on the primary heat source, which provides energy and cost savings.

[0005] There are several challenges and / or constraints in combining or integrating water heating units with heat pumps. Hot water can be demanded irrespective of the current operating mode of the heat pump (e.g., whether the heat pump is in a space heating, space cooling, or idle mode). The operating mode of the heat pump changes the thermal properties of the working fluid in a given line of the working fluid loop, so the thermal connection between the water loop and the working fluid loop needs to be adjusted depending on the operating mode of the heat pump to expand the supplemental heating availability. Otherwise, supplemental heating can only be provided in a limited number of heat pump operating modes, which limits the energy and cost savings that can be realized. Combining the water heating unit and the heat pump may also require substantial reconfiguration of the heat pump to provide the thermal connection between the water and working fluid loops, which can be cost and labor intensive.

[0006] Accordingly, there is a need for systems and methods that enable integrating a water heating unit and a heat pump while providing greater variability and flexibility in the supplemental heating available to the water heating unit, reducing complexity and costs associated with the integration, and otherwise expanding the energy and cost savings that can be realized from such integration.

[0007] This background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.SUMMARY

[0008] In one aspect, an integrated heat pump-water heater system includes a heat pump, which has a refrigerant loop and both an indoor and an outdoor heat exchanger and is operable in multiple modes to condition an indoor space. A water heater is also provided, with a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects the water in the water loop and the refrigerant in the refrigerant loop. A controller, connected to both the heat pump and the water heater, is configured to operate in a space heating mode by determining when water is available to heat the refrigerant and, in response, controlling water flow to the WRHX and directing refrigerant through the WRHX. If an ambient condition is met and water is available, the controller bypasses the outdoor heat exchanger and directs refrigerant to flow between the WRHX and the indoor heat exchanger, so the water heats the refrigerant via the WRHX. If that ambient condition is not met, or if water is unavailable, the system instead directs refrigerant to flow between the indoor heat exchanger and the outdoor heat exchanger so that the refrigerant is heated by the outdoor heat exchanger.

[0009] In another aspect, an integrated heat pump-water heater system includes a heat pump, having a refrigerant loop with both an indoor heat exchanger and an outdoor heat exchanger, that is operable in multiple modes to condition an indoor space. The system also includes a water heater, which has a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects the water loop and the refrigerant loop. A controller is connected to both the heat pump and the water heater. When the system operates in a space heating mode, the controller causes the heat pump to reject heat from the refrigerant to an inlet air stream via the indoor heat exchanger; when operating in a space cooling mode, the controller causes the heat pump to absorb heat into the refrigerant from the inlet air stream via the indoor heat exchanger. In either mode, if the water heater indicates a need for water heating and the heat pump indicates that its refrigerant is available to heat the water, the controller supplies water to the WRHX and directs the refrigerant through it to heat the water. However, if in the space heating mode the refrigerant is not available to heat the water, the controller limits the water supply to the WRHX, regardless of whether the water heater requires heating.

[0010] In yet another aspect, a method of operating an integrated heat pump-water heater system for an indoor space includes circulating a refrigerant through a refrigerant loop of a heat pump operable in a space heating mode and a space cooling mode. The heat pump includes a compressor, an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, a reversing valve, a water-refrigerant heat exchanger (WRHX) thermally connecting the refrigerant loop to a water loop of a water heater, and a network of valves, all positioned on the refrigerant loop. The method further includes operating the heat pump in the space heating mode including positioning the reversing valve to direct the refrigerant from the compressor towards the network of valves and from the outdoor ARHX towards the compressor, positioning the network of valves to direct the refrigerant from the reversing valve towards the WRHX, transferring heat from the refrigerant to water in the water loop via the WRHX, directing the refrigerant from the WRHX successively through the indoor ARHX and the outdoor ARHX, rejecting heat from the refrigerant to an indoor air stream via the indoor ARHX to heat the indoor space, and absorbing heat from an outdoor air stream into the refrigerant via the outdoor ARHX. The method also includes operating the heat pump in the space cooling mode including positioning the reversing valve to direct the refrigerant from the compressor towards the outdoor ARHX and from the network of valves towards the compressor, positioning the network of valves to direct the refrigerant from the outdoor ARHX towards the WRHX, transferring heat from the refrigerant to the water in the water loop via the WRHX, directing the refrigerant from the WRHX towards the indoor ARHX, absorbing heat from the indoor air stream into the refrigerant via the indoor ARHX to cool the indoor space, and rejecting heat from the refrigerant to the outdoor air stream via the outdoor ARHX. The method further includes transferring heat from the refrigerant to the water via the WRHX in both the space heating mode and the space cooling mode to enhance energy efficiency by utilizing the refrigerant to heat the water across the space heating mode and the space cooling mode.

[0011] Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic of a system that includes a heat pump and an integrated water heating unit.

[0013] FIGS. 2-4 depict a first example of an integrated heat pump-water heater system, in various operating modes.

[0014] FIGS. 5-8 are flow diagrams of control algorithms executed by a controller of the system of FIGS. 2-4.

[0015] FIGS. 9-12 depict a second example of an integrated heat pump-water heater system, in various operating modes.

[0016] FIG. 13 is a flow diagram of a control algorithm executed by a controller of the system of FIGS. 9-12.

[0017] FIGS. 14 and 15 depict a third example of an integrated heat pump-water heater system, in various operating modes.

[0018] FIGS. 16-19 depict a fourth example of an integrated heat pump-water heater system, in various operating modes.

[0019] FIGS. 20-22 depict a fifth example of an integrated heat pump-water heater system, in various operating modes.

[0020] FIG. 23 depicts a sixth example of an integrated heat pump-water heater system, in a space heating and standby water heating mode.

[0021] FIGS. 24-26 depict a seventh example of an integrated heat pump-water heater system, in various operating modes.

[0022] FIGS. 27-30 depict an eighth example of an integrated heat pump-water heater system, in various operating modes.

[0023] FIG. 31 depicts a ninth example of an integrated heat pump-water heater system, in a space cooling and standby water heating mode.

[0024] FIGS. 32-34 depict a tenth example of an integrated heat pump-water heater system, in various operating modes.

[0025] FIGS. 35-37 depict an eleventh example of an integrated heat pump-water heater system, in various operating modes.

[0026] FIG. 38 depicts a twelfth example of an integrated heat pump-water heater system, in a space heating and standby water heating mode.

[0027] FIGS. 39 and 40 depict a thirteenth example of an integrated heat pump-water heater system, in various operating modes.

[0028] FIGS. 41 and 42 depict a fourteenth example of an integrated heat pump-water heater system, in various operating modes.

[0029] FIGS. 43A and 43B depict an example method of operating an integrated heat-pump water heater system, in various operating modes.

[0030] FIG. 44 depicts a second example method of operating an integrated water heat pump-water heater, in various operating modes.

[0031] FIG. 45 depicts a third example method of operating an integrated water heat pump-water heater, in various operating modes.

[0032] FIG. 46 depicts a fourth example method of operating an integrated water heat pump-water heater, in various operating modes.

[0033] Corresponding reference numerals indicate corresponding parts throughout the drawings.DETAILED DESCRIPTION

[0034] FIG. 1 is a schematic of a system 10 that includes a heat pump 12 and a water heating unit 14, or water heater 14. In the example system 10, the heat pump 12 operates according to a vapor-compression cycle and circulates a working fluid (e.g., a refrigerant) in a working fluid loop 15 between an indoor unit 16 and an outdoor unit 18. The indoor unit 16 is positioned in the indoor space and includes an indoor heat exchanger 68 (see, e.g., FIG. 2) that operates to condition an air stream directed to an indoor space (e.g., a building or residence), by exchanging heat between the working fluid and the air stream. The outdoor unit 18 is positioned outside the indoor space (e.g., outside the building or residence) and includes an outdoor heat exchanger 70 (see, e.g., FIG. 2) that operates to exchange heat between the working fluid and the outside air. The indoor heat exchanger 68 is also referred to as an indoor air-refrigerant heat exchanger (ARHX) and outdoor heat exchanger 70 is also referred to as an outdoor ARHX.

[0035] The heat exchangers 68, 70 each include a heat exchange coil, respectively, through which the working fluid in the loop 15 is routed. Alternatively, one or both heat exchangers 68, 70 includes a concentric tube (or shell and tube), finned tube, brazed plate, plate and frame, microchannel, or any other suitable heat exchanger design to enable the heat exchangers to function as described. In the examples described, the heat exchangers 68, 70 are equipped with or used in conjunction with one or more fans or blowers 76, 78 (see, e.g., FIG. 2). An indoor fan or blower 76 operates to force an inlet air stream 80 (see, e.g., FIG. 2) to pass across the indoor heat exchanger 68. An outdoor fan or blower 78 operates to force an outside air stream 82 (see, e.g., FIG. 2) to pass across the outside heat exchanger 70.

[0036] The outdoor unit 18 includes a compressor 72 (see, e.g., FIG. 2) that compresses the working fluid. The compressor 72 is any suitable compressor including, but not limited to, scroll, reciprocating, rotary, screw, and centrifugal compressors. The heat pump 12 also includes an expansion device 20. The expansion device 20 is an expansion valve (e.g., a thermal expansion valve). Alternatively, the expansion device 20 is any suitable expansion device, such as an orifice or capillary tube for example. The expansion device 20 is positioned between the indoor unit 16 and the outdoor unit 18. The heat pump 12 also includes a suction line accumulator 74 (see, e.g., FIG. 2) upstream from the compressor 72. The heat pump 12 is also referred to as a vapor-compression system or a refrigeration system.

[0037] In the example shown in FIG. 1, the heat pump 12 operates in a space heating mode, with the indoor heat exchanger of the indoor unit 16 operating as a condenser and the outdoor heat exchanger of the outdoor unit 18 operating as an evaporator. In the space heating mode, the working fluid is compressed using the compressor of the outdoor unit 18 and is routed towards the indoor unit 16 via a line 22 that extends through a partition 11 (e.g., a wall of the building or residence) separating the indoor space and the outside environment. The compressed working fluid rejects heat into the air stream in the indoor unit 16, condensing the working fluid and heating the air stream. The heated air stream is provided to the indoor space. The condensed working fluid exits the indoor unit 16 and flows towards the expansion device 20 via a line 24 extending through the partition 11. The expansion device 20 decompresses or expands the working fluid. The expanded working fluid flows back towards the outdoor unit 18 via the line 24. In the outdoor unit 18, the expanded working fluid absorbs heat from the outside air, evaporating the working fluid. The evaporated working fluid is again compressed using the compressor, and the process repeats.

[0038] The water heater 14 includes a hot water tank 26 that stores hot water. Hot water is supplied to the indoor space via a hot water supply line 28. The hot water tank 26 includes a heat source 30 (e.g., a gas burner and / or an electric resistance heater) that operates to heat the water inside the tank 26. In some examples, the hot water tank 26 is a dual-source tank, and includes two heat sources 30 (e.g., an electric resistance heater and a gas burner). The water heater 14 is integrated with the heat pump 12 via a water heater skid 32 of the water heater 14, also referred to as a water heating integration kit, that includes a water loop 34 and a water-refrigerant heat exchanger (WRHX) 36 positioned on the water loop 34. The water heater skid 32 enables integrating the water heater 14 with the heat pump 12 without substantial reconfiguration of the heat pump 12. For example, as shown in FIG. 1, the water heater skid 32 enables integrating the water heater 14 with the heat pump 12 without substantial re-piping of the lines 22 and 24 of the heat pump 12 and without reconfiguration of the indoor and outdoor units 16, 18. This enables integrating the water heater 14 with the heat pump 12 in a cost-effective manner while reducing the complexity of the design, maintaining a relatively small footprint of the water heater 14, and enabling easy and reliable assembly.

[0039] The water loop 34 includes a line 38 connected to an outlet 27 of the hot water tank 26 and a first three-way valve 42. The first three-way valve 42 connects the line 28, the line 38, and a line 40, and is operable (or positionable) to allow water from the line 28 to flow into the line 38 and / or the line 40. The line 40 extends between the first three-way valve 42 and a second three-way valve 44 downstream from the first three-way valve 42. The second three-way valve 44 connects the line 28, a cold water supply line 46, and a line 48 that extends between the second three-way valve 44 and the WRHX 36. The cold water supply line 46 extends from a third three-way valve 62. The second three-way valve 44 is operable (or positionable) to allow water from the line 28 and / or the cold water supply line 46 to flow into the line 48. Water in the line 48 passes through the WRHX 36 and flows into a hot water return line 50 and towards an inlet 52 of the hot water tank 26.

[0040] Check valves 54 are positioned on the lines 40, 46, and 50 and, in some examples, may additionally or alternatively be positioned on any one or more of the other lines of the water loop 34. Each check valve 54 operates to prevent backflow of water in the respective line on which the check valve is positioned.

[0041] A water pump 56 (or another mechanical fluid movement device) is positioned on the line 40 between the first and second three-way valves 42, 44. The pump 56 operates to move the water through the water loop 34. In some examples, a pump or another mechanical fluid movement device may additionally or alternatively be positioned on any one or more of the other lines of the water loop 34.

[0042] The cold water supply line 46 supplies water from a water supply 58 (e.g., a municipal or city water supply) to the water heater 14. The water supplied from the water supply 58 is used to replenish water in the hot water tank 26. Additionally, or alternatively, the water supplied from the water supply 58 can be provided directly (e.g., as cold or ambient temperature water) to the indoor space via a second supply line 60. The third three-way valve 62 is positioned at a junction of the supply lines 46, 60 and is operable (or positionable) to allow water from the water supply 58 to flow into the supply line 46 and / or the supply line 60.

[0043] The WRHX 36 is positioned on each of the water loop 34, between the lines 48 and 50, and the working fluid loop 15, on the line 22, and thermally connects water in the water loop 34 with the working fluid in the working fluid loop 15. The WRHX 36 operates to exchange heat between the water loop 34 and the working fluid loop 15 and, in particular, to heat the water in the loop 34. In the example of FIG. 1, heat from the working fluid in the line 22 is rejected into the water in the WRHX 36 while the heat pump 12 is operating in the space heating mode. Heating the water in the water loop 34 using the WRHX 36 can reduce the load on the heat source 30, thereby reducing costs and energy usage associated with the water heater 14.

[0044] The system 10 also includes a controller 64 communicatively connected to various components of the system 10, including the heat pump 12 and the water heater 14, and other components of the system 10 such as sensors that monitor operating conditions of the system 10. Although a single controller 64 is shown and described, the controller 64 in some examples includes multiple controllers 64. The multiple controllers 64 may be centralized or decentralized. The controller 64 controls various aspects and parameters of the system 10 during operation.

[0045] The controller 64 receives feedback and monitored process information from one or more sensors of the system 10 for continuous, periodic, or intermittent monitoring of conditions within the system 10 (e.g., temperature and / or pressure of the working fluid in the loop 15, temperature and / or pressure of the water in the loop 34, ambient temperature and / or humidity, a level and / or temperature of the water stored in the tank 26, etc.), among other information. In some examples, the controller 64 additionally or alternatively receives information (e.g., an operating mode request) from a thermostat associated with the heat pump 12. Alternatively, the thermostat may be included as a component of the controller 64. The controller 64 includes a communication interface to communicatively couple the controller 64, via one or more connections 66, to one or more components of the system 10. The one or more connections 66 communicatively couple the controller 64 to the heat pump 12, the water heater 14, and / or other components (e.g., sensors) of the system 10. The communication interface includes, for example, a wired or wireless network adapter and / or a wireless data transceiver for use with a mobile telecommunications network. In this way, the one or more connections 66 communicatively couple the controller 64 to the one or more components of the system 10 via a wired and / or wireless connection.

[0046] The controller 64 is a computer system that includes at least one processor and at least one memory device. The memory device includes a non-transitory computer-readable medium and program that are accessed by the processor and executable to perform the functions described for the controller 64. The controller 64 receives inputs (e.g., monitored conditions of the system 10). For example, the inputs include monitored temperature and pressure information from one or more stages of the heat pump 12 and / or water heater 14, and / or ambient temperature and / or humidity. The controller 64 is operable to process the inputs using one or more control algorithms and generate an output for controlling operation of the system 10, and more particularly, operation of the heat pump 12 and the water heater 14. The controller 64 continuously, periodically, or intermittently generates outputs based on the processed inputs.

[0047] In one example operation, the controller 64 determines a suitable operating mode of the heat pump 12 and generates an output to control the heat pump 12 to operate in the determined operating mode. The operating mode is determined, for example, based on a comparison between a measured temperature of ambient air and a temperature setpoint (e.g., a user specified or pre-determined setpoint). In the illustrated example, the controller 64 controls the heat pump 12 to operate in a space heating mode, described above. The controller 64 also determines a need for heating the water in the water heater 14 (i.e., to provide additional hot water and / or supplemental heating to the water heater 14). The need for water heating is determined, for example, based on a temperature of water in the loop 34 and / or the tank 26, a level of the water in the tank 26, a pre-determined time duration since the last water heating cycle, and / or a user input request. In response to a determined need for water heating, the controller 64 generates an output to control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. The controller 64 also generates output to position the three-way valves 42, 44 to allow the water to flow through the loop 34. Heating the water by operating the pump 56 and the three-way valves 42, 44 to circulate water through the loop 34 is referred to as tank or standby water heating. Additionally, or alternatively, the controller 64 generates an output to control the three-way valves 62, 44 to allow water to flow through the cold water supply line 46, the water loop 34, and the WRHX 36. Heating the water flowing through the loop via the cold water supply line 46 is referred to as groundwater heating. In some examples, the controller 64 may allow the water to continuously or periodically flow through the loop 34 and the WRHX 36 via the cold water supply line 46 and / or the line 38 to enable standby water heating of water in the water heater 14.

[0048] In the example of FIG. 1, the controller 64 may determine whether the need for water heating can be met by circulating water through the loop 34 and the WRHX 36. For example, the controller 64 determines whether the operating mode of the heat pump 12 enables heating water in the loop 34 via the WRHX 36. As shown in FIG. 1, supplemental heating of the water in the loop 34 is available when the heat pump 12 is operating in the space heating mode, since the working fluid in the line 22 is at a suitable stage in the heat pump cycle, specifically, in a compressed, relatively hot vapor stage, for transferring heat to the water in the loop 34. In this example, the controller 64 may determine that water heating is available via the WRHX 36 since the heat pump 12 is operating in the space heating mode, and, in response to a determined need for water heating, the controller 64 generates an output to control the water heater 14 to circulate water through the water loop 34 and the WRHX 36 as described above.

[0049] Other operating modes of the heat pump 12 may not be suitable for providing supplemental heating to the water loop 34. For example, in a space cooling mode, the heat pump is operated in reverse and flow of working fluid (e.g., refrigerant) through the lines is reversed (with the indoor heat exchanger operating as the evaporator and the outdoor heat exchanger operating as the condenser). As such, the working fluid in the line 22 is exiting the evaporator and is at low pressure. At this low pressure stage, prior to compression, the working fluid may not reject heat as effectively as compressed refrigerant. In an idle mode of the heat pump 12, no working fluid may flow through the line and is not available for supplemental heating via the WRHX 36. In these examples, the controller 64 may determine that water heating is not available via the WRHX 36 when the heat pump 12 is in a space cooling mode or an idle mode, and overrides any response to a determined need for water heating.

[0050] The examples described below include additional elements and components, relative to the system 10 of FIG. 1, that provide greater flexibility and variability to the integration of the heat pump 12 and the water heater 14 and enable heating of water in the water heater 14 in a greater number of operating modes of the heat pump 12. Additionally, in some examples, heating of working fluid of the heat pump 12 via the water heater 14 is enabled. The controller 64 is also equipped to execute various control algorithms, described below, that enable improved and well-controlled integration of the heat pump 12 and the water heater 14, and expand the ability of the heat pump 12 and the water heater 14 to each fulfill their respective demands for the indoor space while providing cost and energy savings via their integration.

[0051] Accordingly, the examples described below relate to integrated heat pump-water heater systems that include a heat pump including a working fluid loop and operable in multiple operating modes for an indoor space, a water heater including a water loop, and a water-refrigerant heat exchanger (WRHX) that thermally connects the water loop and the working fluid loop, where heat transfer occurs between the water loop and the working fluid loop in the multiple operating modes. In various examples, depending on the operating mode of the heat pump and a determined need for water heating in the water heater, a controller controls a path that the working fluid travels in the working fluid loop (e.g., by controlling positions of each of a network of valves) in order to enable simultaneously operating the heat pump in its designated mode and transferring heat between the water heater and the heat pump.

[0052] In the examples described below, the systems include elements and components that are included in the system 10 of FIG. 1, which are indicated using like reference numerals. Description of the elements and components above applies similarly to the elements and components included in the systems described below and indicated using like reference numerals unless expressly stated otherwise or the context clearly indicates otherwise.

[0053] The elements and components of the systems described below can be combined in any suitable combination. Any feature or element described with reference to one of the systems that is not described with reference to another one of the systems is not to be interpreted as limiting in any sense, and such element and feature can be included in such other system unless expressly stated otherwise or the context clearly indicates otherwise.

[0054] FIGS. 2-4 depict a first example of an integrated heat pump-water heater system 100 that includes a heat pump 102 operable in multiple operating modes and the water heater 14 integrated with the heat pump 102. The heat pump 102 includes similar elements and components as the heat pump 12 of FIG. 1, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIG. 1.

[0055] In this example, the system 100 includes a first reversing valve 106 and a network of valves 107 on a working fluid loop 105 of the heat pump 102 to control flow of a working fluid (e.g., refrigerant) through the loop 105. The first reversing valve 106 is operable (or positionable) to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 105 based on an operating mode (e.g., space heating or space cooling) of the heat pump 102. The network of valves 107 is connected to the first reversing valve 106. The network of valves 107 in this example includes a second reversing valve 108 and a third reversing valve 110. The valves 108, 110 of the network of valves 107 are independently operable to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 102. In particular, the valves 108, 110 are operable to direct the flow of the working fluid such that the working fluid flows through the WRHX 36 at a suitable stage in the heat pump cycle (e.g., in a compressed, relatively hot vapor stage) for transferring heat to the water in the loop 34 at different operating modes of the heat pump 102. In a space heating mode of the heat pump 102 (FIG. 2), the indoor heat exchanger 68 operates as the condenser (rejecting heat into the inlet air stream 80) and the outdoor heat exchanger 70 operates as the evaporator (absorbing heat from the outside air stream 82). In a space cooling mode of the heat pump 102 (FIG. 3), the indoor heat exchanger 68 operates as the evaporator (absorbing heat from the inlet air stream 80) and the outdoor heat exchanger 70 operates as the condenser (rejecting heat into the outside air stream 82).

[0056] The first reversing valve 106 is connected to the compressor 72 by a discharge line 112 downstream from the compressor 72 and by a suction line 118 upstream from the compressor 72. The first reversing valve 106 is also connected to the outdoor heat exchanger 70 by a line 114 and the second reversing valve 108 by a line 116. The second reversing valve 108 is connected to the third reversing valve by a line 122 and by a line 124. The WRHX 36 is positioned on the line 122 between the second reversing valve 108 and the third reversing valve 110. The second reversing valve 108 is also connected to the outdoor heat exchanger 70 by a line 120. The third reversing valve 110 is also connected to the indoor heat exchanger 68 by a line 126 and by a line 128. The expansion device 20 is positioned on the line 126 between the indoor heat exchanger 68 and the third reversing valve 110.

[0057] Referring to FIG. 2, in a space heating mode of the heat pump 102, the first reversing valve 106 is in a first position in which working fluid exiting the compressor 72 via the discharge line 112 is directed by the first reversing valve 106 towards the network of valves 107 and, specifically, the second reversing valve 108 via the line 116. The working fluid is then directed by the network of valves 107 to flow through the WRHX 36 as compressed, relatively hot fluid downstream from the compressor 72 for transferring heat to the water in the loop 34, and then through the indoor heat exchanger 68, the expansion device 20, and through the second reversing valve 108. In particular, each of the second and third reversing valves 108, 110 are in a first position such that the working fluid from the lines 112 and 116 flows through the second reversing valve 108 into the line 122 and through the WRHX 36, and then through the third reversing valve 110 into the line 128. The working fluid 128 then flows from the line 128, through the indoor heat exchanger 68, into the line 126 and through the expansion device 20. The working fluid 126 is directed from the line 126 by the third reversing valve 110 into the line 124 and back through the second reversing valve 108. The second reversing valve 108 then directs the working fluid towards the outdoor heat exchanger 70 via the line 120. The working fluid exits the outdoor heat exchanger 70 via the line 114 and is directed by the first reversing valve 106 in the first position into the suction line 118 and back towards the compressor 72.

[0058] Referring to FIG. 3, in a space cooling mode of the heat pump 102, the first reversing valve 106 and the network of valves 107 are each in a second position, reversed relative to the respective first position, to reverse the flow direction of the working fluid in the loop 105 while still enabling the working fluid to flow through the WRHX 36 as compressed, relatively hot fluid downstream from the compressor 72 for transferring heat to the water in the loop 34. The first reversing valve 106 in the second position directs the working fluid exiting the compressor 72 via the discharge line 112 towards the outdoor heat exchanger 70. The working fluid exits the outdoor heat exchanger 70 and flows through the line 120 towards the second reversing valve 108 which, in the second position, directs the working fluid from the line 120 into the line 122 and through the WRHX 36. In relatively hot outside temperature conditions, a relatively small amount of heat is transferred between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70, such that the working fluid in the lines 120, 122 has the capability of rejecting heat into the water loop 34 via the WRHX 36. Alternatively, in some examples, such as in mild outside temperature conditions where a relatively greater amount of heat transfer can take place using the fan 78. The outdoor fan 78 can be cycled, idle and / or bypassed to maintain heat in the working fluid for rejecting into the water loop 34 via the WRHX 36. Operation and / or bypass of the outdoor fan 78 in the space cooling mode can be controlled by monitoring the ambient conditions and / or conditions of the working fluid in the line 120 via a sensor 130 (e.g., temperature sensor) to control the heat rejection capability of the working fluid flowing through the WRHX 36 in the space cooling mode of the heat pump 102.

[0059] Still referring to FIG. 3, the working fluid flows from the WRHX 36 through the line 122 towards the third reversing valve 110. In the second position, the third reversing valve directs the working fluid into the line 126 and through the expansion device 20. The working fluid then flows through the indoor heat exchanger 68, into the line 128 and back through the third reversing valve 110 which then directs the working fluid into the line 124 and towards the second reversing valve 108. The second reversing valve 108 in the second position directs the working fluid from the line 124 towards the first reversing valve 106 via the line 116. The first reversing valve 106 in the second position directs the working fluid from the line 116 into the suction line 118 and back towards the compressor 72.

[0060] In both the space heating mode (FIG. 2) and the space cooling mode (FIG. 3) of the heat pump 102, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0061] Referring to FIG. 4, the system 100 is also operable in a dedicated water heating mode. In the illustrated example, the system 100 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58. Additionally, or alternatively, the system 100 can be operated in the dedicated water heating mode to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the first reversing valve 106 and the network of valves 107 are each positioned in the first position and direct flow of the working fluid through the working fluid loop 105 as described above for the space heating mode with reference to FIG. 2. The outdoor heat exchanger 70 is operated as the evaporator, as described above for the space heating mode with reference to FIG. 2. The indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 102. The water heater 14 is operated as described above to flow water through the water loop 34 for heating via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0062] In some examples, the system 100 is also operable in a space heating only mode or a space cooling only mode. In these operating modes, the heat pump 102 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34).

[0063] The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 102 in the space heating and / or space cooling mode. The controller 64 may determine that the water heater 14 is available for hydronic heating when the controller 64 determines that there is hot water available in the water heater 14 for heating the working fluid (e.g., based on a temperature of the water in the loop 34, a level and / or temperature of the water stored in the tank 26, or another operating condition of the water heater 14). The controller 64 may also determine a need for supplemental heating of the working fluid in the heat pump 102 using the WRHX 36 (e.g., based on a temperature of the working fluid in the loop 15, ambient temperature and / or humidity, or another operating condition of the heat pump 102). In response, the controller 64 can initiate a hydronic heating mode by controlling the water heater 14 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0064] FIGS. 5-8 depict example flow diagrams of control algorithms according to which the controller 64 controls operation of the system 100 of FIGS. 2-4. Description of the controller 64 with reference to FIG. 1 applies to the controller 64 of the system 100 unless expressly stated otherwise or the context clearly indicates otherwise. As described above with reference to FIG. 1, the controller 64 receives inputs (e.g., monitored conditions of the system 100), processes the inputs using control algorithms (e.g., those described below for FIGS. 5-8), generates output for controlling operation of the heat pump 102 and the water heater 14. In the system 100, the inputs include measured parameters received from sensors 130, 132, 134, 136, 138 (e.g., temperature sensors) associated with the heat pump 102 and the water heater 14. In the illustrated example, the sensors include a temperature sensor 130 positioned on the line 120 between the second reversing valve 108 and the outdoor heat exchanger 70, a temperature sensor 132 positioned on the line 38 of the water loop 34 downstream from the outlet 27 of the tank 26, a level sensor 134 connected to the tank 26, an ambient temperature sensor 136, and a temperature sensor 138 for the inlet air stream 80. Any suitable number of sensors (e.g., temperature, pressure, or other sensors) can be used and located at any suitable position in the heat pump 102 (e.g., on the working fluid loop 105) and / or in the water heater 14 (e.g., on the water loop 34) to enable the controller to function as described.

[0065] Referring to FIG. 5, which shows a flow diagram 500 of a main control algorithm for the system 100, the controller 64 monitors 502 a temperature of the water in the water loop 34 in the line 38 proximate the outlet 27 of the tank 26 (i.e., the water exiting the tank 26) via the sensor 132. Additionally, or alternatively, the controller 64 monitors 502 a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14. The controller 64 may also log the monitored 502 temperature over a predetermined time period (e.g., 48 hours). Based on the monitored 502 temperature, the controller 64 determines 504 whether the temperature of the water exiting the tank 26 is rising or falling. An increase in the monitored 502 temperature is indicative that there is not an immediate need for water heating in the water heater 14, and the controller 64 then determines 506 a requested operating mode of the heat pump 102 for further instruction on how to control the system 100, described below. A decrease in the monitored 502 temperature is indicative that there is a need for water heating in the water heater 14.

[0066] In response to determining 504 that the monitored 502 temperature is decreasing, the controller 64 determines 508 whether a pre-determined time period (e.g., 15 minutes) has elapsed since the last call for water heating (or since the last water heating cycle). For example, the controller 64 determines 508 whether the pre-determined time period has elapsed since the last instance of the water pump 56 being operated to circulate water through the water loop 34. When it is determined 508 that the pre-determined time period has not elapsed, the controller 64 reverts back to monitoring 502 the temperature of the water exiting the tank 26 (or another suitable operating condition of the water heater 14), or another suitable operation to enable the controller 64 to function as described.

[0067] When it is determined 508 that the pre-determined time period has elapsed, the controller 64 initiates a water heating operation at 510 to transfer heat between the working fluid loop 105 and the water loop 34 to provide water heating. For example, the controller 64 controls 510 (e.g., turns on) the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, and positions the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 controls 510 the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. Concurrently, depending on the operating mode of the heat pump 102, the controller 64 controls the network of valves 107 to direct the working fluid through the WRHX 36 at a suitable stage in the heat pump cycle for transferring heat with the water in the water loop 34.

[0068] During the water heating operation initiated at 510, the controller 64 continues to monitor 502 the temperature of the water exiting the tank 26. Additionally, or alternatively, the controller 64 monitors 502 a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14. The controller 64 determines 512 whether to continue or cease the water heating operation at 512 based on whether the monitored 502 temperature (or condition) meets a predefined or predetermined criterion. For example, the controller 64 determines 512 whether to continue or cease the water heating operation at 512 based on whether the temperature of the water exiting the tank 26 meets a predefined temperature value or is within a predefined temperature range (e.g., whether the temperature of the water is within 5° F. of a maximum water temperature logged over the pre-determined time period at 502). If the monitored 502 temperature (or condition) meets the predefined criterion, the water heating operation is ceased at 514 (e.g., by turning of the water pump 56 and / or limiting flow of water through the water loop 34) and the controller 64 reverts back to monitoring 502 the temperature of the water exiting the tank 26 (or another suitable operating condition of the water heater 14), or another suitable operation to enable the controller 64 to function as described.

[0069] If the monitored 502 temperature (or condition) does not meet the predefined criterion, the controller 64 may continue the water heating operation initiated at 510 and continue to monitor 502 the temperature (or condition) against the predefined criterion. At this stage, the controller 64 also determines 506 a requested operating mode of the heat pump 102 for further instruction on how to control the system 100. The controller 64 may receive the requested operating mode information directly from a user input and / or from a thermostat associated with the heat pump 102.

[0070] FIG. 6 is an example flow diagram 600 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is operating in a space heating mode (as shown in FIG. 2). During the space heating mode, the outdoor heat exchanger 70 operates as the evaporator and absorbs heat from the outside air stream 82. In cold outside air conditions, this creates the risk of frost building up on the outdoor coils of the outdoor heat exchanger 70. The heat pump 102 is periodically operated in a defrost mode, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove the frost. When the heat pump 102 is operating in the space heating mode, the controller 64 determines 602 whether there is a demand for a defrost mode operation. A demand for the defrost mode may occur, for example, when a pre-determined period of time has elapsed since the last defrost mode operation. Additionally, or alternatively, a demand for the defrost mode operation may occur when a difference between defined temperature setpoint (e.g., a user defined temperature setpoint at the thermostat) and the outside air temperature is equal to or greater than a predetermined value, e.g., greater than or equal to 15° F.

[0071] When a demand for the defrost mode operation occurs, the controller 64 initiates the defrost mode operation, or defrost cycle, at 606. This includes positioning 608 the first reversing valve 106 in the second position and each the network of valves 107 of the heat pump 102 in the first position to direct the working fluid in a defrost mode flow direction (see FIG. 11, described below), and operating 610 the outdoor heat exchanger 70 as a condenser such that compressed, hot working fluid flows through the outdoor coils for the defrost operation. The outdoor fan 78 may be idle (e.g., turned off) to enhance the defrost operation on the outdoor coils. The indoor heat exchanger 68 is controlled 612 to be idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space during the defrost cycle. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode.

[0072] During the defrost cycle initiated at 606, the controller 64 also determines 614 whether to operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. As described above, when the controller 64 implements the control algorithm of FIG. 6, there may not be an immediate need for water heating in the water heater 14 as determined at 504. This may signal that there is hot water available in the water heater 14 to provide heating to the working fluid in the loop 105 via the WRHX 36. Accordingly, during the defrost cycle, the controller 64 may operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, such that the hot water heats the working fluid in the line 122 before the working fluid is directed back towards the compressor 72. Alternatively, in some examples, the controller 64 may determine that there is not hot water available in the water heater 14 to heat the working fluid in the loop 105 when the heat pump 102 is in the defrost cycle. For example, referring to FIG. 5, when the monitored 502 temperature (or condition) does not meet the predefined criterion, this may signal that there is not hot water available for heating the working fluid. In these situations, the controller 64 does not operate the water pump 56, such that a suitable level of hot water in the tank 26 is maintained to fulfill hot water demands in the indoor space. In this way, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 102 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. If, when there is no hot water available for heating the working fluid and the water pump 56 is turned off, the demand for the defrost cycle is still active, the controller 64 may operate (e.g., turn on) the indoor fan 76 such that heat can be absorbed into the working fluid at the indoor heat exchanger 68.

[0073] When the controller 64 determines (at 616) that the demand for the defrost cycle of the heat pump 102 terminates (e.g., after a pre-determined defrost duration), or when the controller 602 determines that there is not a demand for a defrost cycle at 602, the controller 64 initiates (or continues) the space heating mode of the heat pump 102 at 618. In the space heating mode, as shown in FIG. 2, the controller 64 positions 620 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the first position, operates 622 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and operates 624 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils. At 626, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 600 at 628 described below. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0074] At 628, the controller 64 determines whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). When the controller 64 determines 628 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. This controls (maintains) the ability of the heat pump 102 to provide the additional heating of the inlet air stream 80. In response, the controller 64 does not operate the water heater 14 to flow water through the water loop 34 and WRHX 36, irrespective of any demand for heating of water in the water heater 14. In this way, as described above, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 102 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. The controller 64 then reverts to operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0075] When the controller 64 determines 628 that there is not a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 meets the setpoint temperature), then the controller determines that there is availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. At 630, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 630 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 630 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 102 in the space heating mode and, at 632, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 630, or to any one of operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0076] When the controller 64 determines 630 that there is a need for water heating in the water heater 14, at 634 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 634 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. During the water heating operation initiated at 634, the controller 64 also continues to monitor at 636 whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). If there is not a demand for additional heating of the inlet air stream 80, the water heating operation initiated at 634 may continue until there is no longer a need for water heating in the water heater 14. When the controller 64 determines 636 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. In response, the controller 64 controls the water heater 14 to stop flowing water through the water loop 34 and WRHX 36 (e.g., by turning off the pump 56), irrespective of the demand for heating of water in the water heater 14 determined at 634. The controller 64 may then revert to operation 630, or to any one of operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0077] FIG. 7 is an example flow diagram 700 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is operating in a space cooling mode (as shown in FIG. 3). The controller 64 initiates (or continues) the space cooling mode of the heat pump 102 at 702. In the space cooling mode, as shown in FIG. 3, the controller 64 positions 704 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the second position, operates 706 the outdoor heat exchanger 70 as the condenser of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils, and operates 708 the indoor heat exchanger 68 as the evaporator of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils. At 710, the controller 64 determines whether the demand for the space cooling mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 700 at 712 described below. If the demand for the space cooling mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0078] At 712, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 712 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 712 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 102 in the space cooling mode and, at 722, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 702, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0079] When the controller 64 determines 712 that there is a need for water heating in the water heater 14, at 714 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 634 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0080] As described above, in the space cooling mode, the ability of the working fluid to transfer heat into the water in the loop 34 varies based on the outside temperature conditions, which affect the amount of heat transfer that occurs between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70. Smaller heat transfer in the outdoor heat exchanger 70, which is more likely to occur in hot temperature outside conditions, provides more capability of the working fluid in the line 122 to reject heat into the water loop 34 via the WRHX 36. The controller 64 monitors at 716 the ability of the working fluid exiting the outdoor heat exchanger 70 to transfer heat into the water in the loop 34 via the WRHX 36 during the water heating operation initiated at 714. In this example, the controller 64 monitors 716 the temperature of the working fluid exiting the outdoor heat exchanger 70 in the line 120 via the sensor 130. Additionally, or alternatively, the controller 64 may monitor 716 any suitable operating condition of the heat pump 102 indicative of the ability of the working fluid to transfer heat via the WRHX while the heat pump 102 is in the space cooling mode. For example, the controller 64 monitors 716 the ambient temperature via the sensor 136 and / or a temperature of the working fluid in the 122 upstream from the WRHX 36. At 718, the controller 64 determines whether the monitored 716 condition satisfies a predetermined criterion that is indicative of effective heat transfer between the working fluid in the line 122 and the water in the loop 34 via the WRHX 36. For example, the controller 64 determines whether the monitored 716 temperature of the working fluid in the line 120 exiting the outdoor heat exchanger 70 meets or exceeds a threshold or predetermined temperature value (e.g., 130° F.) that is indicative of effective heat transfer. If the monitored 716 condition (e.g., temperature) meets or exceeds the predetermined criterion (e.g., the predetermined value), the controller 64 takes no further action and allows operation to continue. If the monitored 716 condition (e.g., temperature) is below the predetermined criterion (e.g., the predetermined temperature value), the controller 64 may cycle, bypass, and / or operate as idle the outdoor fan 78 at 720. The controller 64 may then revert to operation 702, operation 712, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0081] FIG. 8 is an example flow diagram 800 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is not operating in a space cooling mode or a space heating mode (i.e., when there is no request for conditioning the inlet air stream 80 via the heat pump 102). When the heat pump 102 is not being used to condition the inlet air stream 80, the controller determines at 802 whether or not there is a need for water heating in the water heater 14. This can be determined at 802 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 802 that there is not a need for water heating in the water heater 14, the controller 64 maintains the heat pump 102 in the idle mode, or turns the heat pump 102 off, at 804. This includes de-energizing the first reversing valve 106 and the network of valves 107 at 808 and fans 76, 78 of the indoor and outdoor heat exchangers 68, 70 at 810. The controller 64 also controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 802, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0082] When the controller 64 determines 802 that there is a need for water heating in the water heater 14, the controller 64 initiates the dedicated water heating mode of the system 100 (see FIG. 4) at 812. As described with reference to FIG. 4, in the dedicated water heating mode, the controller 64 positions 814 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the first position, and operates 816 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. At 818, the controller 64 also controls the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positions the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 818 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. At 820, the controller 64 determines whether the demand for the dedicated water heating mode is still active. If so, the controller 64 continues through the operations 814-818. If the demand for the dedicated water heating mode has terminated (e.g., based on the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14), then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0083] FIGS. 9-12 depict a second example of an integrated heat pump-water heater system 900 that includes a heat pump 902 operable in multiple operating modes and the water heater 14 integrated with the heat pump 902. The heat pump 902 includes elements and components that are included in the heat pump 12 of FIG. 1 and the heat pump 102 of FIGS. 2-4, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4.

[0084] In this example, the system 900 includes the first reversing valve 106 and a network of valves 907 on a working fluid loop 905 of the heat pump 902 to control flow of a working fluid (e.g., refrigerant) through the loop 905. The first reversing valve 106 is operable (or positionable) as described above to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 905 based on an operating mode (e.g., space heating or space cooling) of the heat pump 902. The network of valves 907 is connected to the first reversing valve 106 and includes the second reversing valve 108 and the third reversing valve 110. The second and third reversing valves 108, 110 of the network of valves 907 are independently operable (or positionable) to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 902, as described above for the network of valves in FIGS. 2-4. The system 900 is operable in the operating modes (e.g., the space heating mode of FIG. 2, the space cooling mode of FIG. 3, and the dedicated water heating mode of FIG. 4) described above for the system 100 and includes the functionality and advantages of the system 100.

[0085] Additionally, in this example, the network of valves 907 includes a first three-way valve 904 positioned between the line 122 and the second reversing valve 108 and a second three-way valve 906 positioned between the third reversing valve 110 and the line 126. The three-way valves 904, 906 are connected by a bypass line 908, and are operable (or positionable) to direct fluid through the bypass line 908 to provide greater variability and flexibility in operating the system 900. For example, the three-way valves 904, 906 and the bypass line 908 enable expanding the operating modes in which the system 900 can be operated while heat is transferred between the loop 905 and the water loop 34 via the WRHX 36, as will be described below.

[0086] Referring to FIG. 9, in a space cooling mode of the heat pump 902, the reversing valves 106, 108, and 110 are each in the second position, similar to the space cooling mode of the heat pump 102 shown in FIG. 3. As described above, the reversing valves 106, 108, 110 in their respective second position direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 114 towards and through the outdoor heat exchanger 70, into the line 120 towards and through the second reversing valve 108, into the line 122 towards and successively through the WRHX 36 and the third reversing valve 110, into the line 126 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 128 towards and back through the third reversing valve 110, into the line 124 towards and back through the second reversing valve 108, into the line 116 towards and back through the first reversing valve 106, and into the suction line 118 towards the compressor 72. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed to maintain heat in the working fluid for rejecting into the water loop 34 via the WRHX 36. In the space cooling mode of FIG. 9, each of the first three-way valve 904 and the second three-way valve 906 are in a first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0087] Referring to FIG. 10, in a space heating mode of the heat pump 902, the reversing valves 106, 108, and 110 are each in the first position, similar to the space heating mode of the heat pump 102 shown in FIG. 3. As described above, the reversing valves 106, 108, 110 in their respective first position direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 116 towards and through the second reversing valve 108, into the line 122 towards and successively through the WRHX 36 and the third reversing valve 110, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and successively through the expansion device 20 and the third reversing valve 110, into the line 124 towards and back through the second reversing valve 108, into the line 120 towards and through the outdoor heat exchanger 70, into the line 114 towards and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the space heating mode of FIG. 10, each of the first three-way valve 904 and the second three-way valve 906 are in the first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0088] In both the space heating mode (FIG. 10) and the space cooling mode (FIG. 9) of the heat pump 902, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0089] FIG. 11 depicts the system 900 in a defrost mode, described above with reference to FIG. 6. The system 100 of FIGS. 2-4 is also operable in the defrost mode shown in FIG. 11. As described above, during space heating, the heat pump 902 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, the first reversing valve 106 is in the second position, and the second and third reversing valves 108, 110 are in the first position. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The reversing valves 106, 108, 110 are positioned to direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 114 towards and through the outdoor heat exchanger 70, into the line 120 towards and through the second reversing valve 108, into the line 124 towards and through the third reversing valve 110, into the line 126 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 128 towards and through the third reversing valve 110, into the line 122 towards and successively through the WRHX 36 and the second reversing valve 110, into the line 116 towards and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the defrost mode of FIG. 11, each of the first three-way valve 904 and the second three-way valve 906 are in the first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0090] In the defrost mode of FIG. 11, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 902 is in the defrost mode as described above with reference to FIG. 6. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIG. 6, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0091] FIG. 12 depicts the system 900 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 904, 906 and the bypass line 908. In this space heating mode, the outdoor components of the heat pump 902, including the compressor 72 and the outdoor fan 78, are idle. The network of valves 907 is operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 902 as described below. To enable a thermosiphon or compressor-free mode of the heat pump 902, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 905 using natural convection rather than by mechanical force. The system 900 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0092] In the thermosiphon or compressor-free mode of FIG. 12, each of the three-way valves 904, 906 is in a second (bypass) position to allow the working fluid to flow through the bypass line 908 between the lines 122 and 126. The three-way valves 904, 906 in the second position restrict flow of the working fluid into the lines 116, 120, and 124, which isolates the second reversing valve 108, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70 from flow of the working fluid. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The third reversing valve 110 is in the first position to direct fluid flowing through the line 122 into the line 128 towards the indoor heat exchanger 68. As shown in FIG. 12, in the thermosiphon or compressor-free mode, the third reversing valve 110 in the first position and the first and second three-way valves 904, 906 in the second position direct the working fluid through the loop 905 as follows: working fluid flows through the line 122 and the WRHX 36, towards and through the third reversing valve 110, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and successively through the expansion device 20 and the second three-way valve 906, into the line 908 towards and through the first three-way valve 904, and back into the line 122. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 905 by natural convection.

[0093] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 12 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0094] The system 900 is operable in other operating modes than those shown in FIGS. 9-12 and described above. For example, the system 900 is operable in a dedicated water heating mode, as shown in FIG. 4 and described above for the system 100. In the dedicated water heating mode of the system 900, the reversing valves 106, 108, 110 are each in the first position and the first and second three-way valves 904, 906 are each in the first (non-bypass) position. In some examples, the system 900 is also operable in a space heating only mode or a space cooling only mode. In the space heating only and space cooling only operating modes, the heat pump 902 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). The system 900 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 902 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 902 demand, as described above.

[0095] Description of the controller 64 with reference to FIGS. 2-4 applies to the controller 64 of the system 900 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 900 using a control algorithm shown in FIGS. 5-8 and described above.

[0096] FIG. 13 is a flow diagram 1300 of another example control algorithm according to which the controller 64 controls the system 900 when the heat pump 902 is operating in a space heating mode (as shown in FIG. 10). As described above, during the space heating mode, there is a risk of frost building up on the outdoor coils of the outdoor heat exchanger 70, and the heat pump 902 is periodically operated in a defrost mode to remove the frost. The controller 64 determines at 1302 whether there is a demand for a defrost mode operation (or defrost cycle). For example, the controller 64 determines 1302 whether there is a demand for a defrost based on whether a pre-determined period of time has elapsed since the last defrost cycle.

[0097] When a demand for the defrost cycle occurs, the controller 64 initiates the defrost cycle at 1306. An example of a defrost mode operation is shown in FIG. 11. The controller 64 positions 1308 each of the first reversing valve 106 and the network of valves 907 of the heat pump 902 as shown in FIG. 11, turns off the indoor fan 76 at 1312, and operates 1310 the outdoor heat exchanger 70 as a condenser such that compressed, hot working fluid flows through the outdoor coils for the defrost operation. The outdoor fan 78 may be idle (e.g., turned off) to enhance the defrost operation on the outdoor coils. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode.

[0098] During the defrost cycle initiated at 1306, the controller 64 also determines whether to operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. As described above, during a defrost mode operation, there may not be an immediate need for water heating in the water heater 14 (e.g., as determined at 504 of FIG. 5). This may signal that there is hot water available in the water heater 14 to provide heating to the working fluid in the loop 105 via the WRHX 36. Accordingly, during the defrost cycle, at 1314, the controller 64 may operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, such that the hot water heats the working fluid in the line 122 before the working fluid is directed back towards the compressor 72. Alternatively, in some examples, the controller 64 may determine that there is not hot water available in the water heater 14 to heat the working fluid in the loop 105 when the heat pump 102 is in the defrost cycle. For example, at 1316, when the temperature of the water exiting the tank 26 (or another condition of the water heater 14) does not meet the predefined criterion, this may signal that there is not hot water available for heating the working fluid. In these situations, at 1318, the controller 64 does not operate the water pump 56, or turns off the water pump 56, such that a suitable level of hot water in the tank 26 is maintained to fulfill hot water demands in the indoor space. When the water pump 56 is turned off at 1318, and the demand for the defrost cycle is still active, the controller 64 may operate (e.g., turn on) the indoor fan 76 such that heat can be absorbed into the working fluid at the indoor heat exchanger 68. The controller 64 then reverts to operation 1302, operation 1306, operation 1316, or operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0099] When the controller 64 determines (at 1320) that the demand for the defrost mode operation of the heat pump 902 terminates (e.g., after a pre-determined defrost duration), or when the controller 602 determines that there is not a demand for a defrost cycle at 1302, the controller 64 initiates (or continues) a space heating mode of the heat pump 902. In the example flow diagram, the controller 64 makes a series of determinations at 1304 and 1322 to determine whether to initiate the space heating mode of FIG. 10, in which both the indoor heat exchanger 68 and the outdoor heat exchanger 70 are operated, or the thermosiphon (or compressor-free) space heating mode of FIG. 12, in which the outdoor components of the heat pump 902 are inactive and the working fluid is driven through the loop 905 by gravity and a temperature and / or pressure differential between the indoor heat exchanger 68 and the WRHX 36 as described above. At 1304, the controller 64 determines whether an outside condition (e.g., ambient temperature measured by the sensor 136) meets or exceeds a predefined or predetermined criterion (e.g., a threshold or predetermined temperature value). In the example flow diagram 1300, the controller 64 determines 1304 whether the ambient temperature is greater than 45° F.

[0100] When the controller 64 determines 1304 that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is not greater than 45° F.), the controller 64 initiates the space heating mode of FIG. 10. In this space heating mode, as shown in FIG. 10, the controller 64 positions 1326 each of the first reversing valve 106, the second reversing valve 108, and the third reversing valve 108 in the first position, positions 1328 the first and second three-way valves 904, 906 in the first (non-bypass) position, operates 1330 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and operates 1332 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils. At 1334, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 1300 at 1336 described below, or reverts to operation 1304 to determine whether the thermosiphon space heating mode is available, or another suitable operation to enable the controller 64 to function as described. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 902 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0101] When the controller 64 determines 1304 that the outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), the controller 64 determines 1322 whether there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 12. This can be determined as described above, for example, by determining 1322 that the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid. When the controller 64 determines that there is hot water available at 1322, the controller 64 initiates the thermosiphon space heating mode at 1336. When the controller 64 determines that there is not hot water available at 1322, the controller 64 initiates 1324 the space heating mode of FIG. 10 as described above.

[0102] In the thermosiphon space heating mode initiated at 1336, as shown in FIG. 12, the controller 64 positions 1338 the third reversing valve 108 in the first position, positions 1340 the first and second three-way valves 904, 906 in the second (bypass) position, operates 1342 (e.g., turns on) the water pump 56 and positions the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, operates 1344 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and fully opens 1346 (or bypasses) the expansion device 20. As described above, in the thermosiphon space heating mode, the compressor 72 and the outdoor heat exchanger 68 are isolated from the working fluid and these components may be idle or turned off when the thermosiphon space heating mode is initiated 1336. At 1348, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues to operate the system 900 in the thermosiphon space heating mode, or reverts to operation 1304 to determine whether the thermosiphon space heating mode is still available. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 902 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0103] At 1350, while the space heating mode initiated at 1324, the controller 64 determines whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). When the controller 64 determines 1350 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 905 to heat water in the loop 34 via the WRHX 36. This controls (maintains) the ability of the heat pump 902 to provide the additional heating of the inlet air stream 80. In response, the controller 64 does not operate the water heater 14 to flow water through the water loop 34 and WRHX 36, irrespective of any demand for heating of water in the water heater 14. In this way, as described above, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 902 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. The controller 64 then continues to operate the system 900 in the space heating mode of FIG. 10, reverts to operation 1304 to determine whether the thermosiphon space heating mode is available, or reverts to operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0104] When the controller 64 determines 1350 that there is not a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 meets the setpoint temperature), then the controller determines that there is availability for using the working fluid in the loop 905 to heat water in the loop 34 via the WRHX 36. At 1352, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 1352 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 1352 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 902 in the space heating mode and, at 1354, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 then continues to operate the system 900 in the space heating mode of FIG. 10, or reverts to any one of operation 1350, operation 1352, operation 1304, or operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0105] When the controller 64 determines 1352 that there is a need for water heating in the water heater 14, at 1356 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 1356 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. During the water heating operation initiated at 1356, the controller 64 also continues to monitor at 1358 whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). If there is not a demand for additional heating of the inlet air stream 80, the water heating operation initiated at 1356 may continue until there is no longer a need for water heating in the water heater 14. When the controller 64 determines 1356 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. In response, the controller 64 controls the water heater 14 to stop flowing water through the water loop 34 and WRHX 36 (e.g., by turning off the pump 56), irrespective of the demand for water heating of water in the water heater 14 determined at 1356. The controller 64 may then revert to operation 1304, operation 1350, operation 1352, or operation 506 of FIG. 5, or another suitable operation to enable the controller 64 to function as described.

[0106] FIGS. 14 and 15 depict a third example of an integrated heat pump-water heater system 1400 that includes a heat pump 1402 operable in multiple operating modes and the water heater 14 integrated with the heat pump 1402. The heat pump 1402 includes elements and components that are included in the heat pump, the heat pump 102 of FIGS. 2-4, and the heat pump 902 of FIGS. 9-12, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0107] In this example, the system 1400 includes the first reversing valve 106 and a network of valves 1407 on a working fluid loop 1405 of the heat pump 1402 to control flow of a working fluid (e.g., refrigerant) through the loop 1405. The first reversing valve 106 is operable (or positionable) as described above to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 1405 based on an operating mode (e.g., space heating or space cooling) of the heat pump 1402. The network of valves 1407 is connected to the first reversing valve 106 and, in this example, includes six solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 and six three-way valves 1414, 1416, 1418, 1420, 1422, and 1424, each of which are independently operable (or positionable) to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 902, as described above for the network of valves 107 in FIGS. 2-4 and the network of valves 907 in FIGS. 9-12. The system 900 is operable in the operating modes described above for the system 100 and the system 900, and includes the functionality and advantages of the system 100 and the system 900. The six solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 and six three-way valves 1414, 1416, 1418, 1420, 1422, and 1424 are operable (positionable) to direct working fluid through the loop similar to the network of valves 907 of FIGS. 9-12.

[0108] In the example system 1400, the network of valves 1407 is positioned as follows. A first three-way valve 1414 is positioned on the line 122 and a second three-way valve 1416 is positioned at a junction between the line 120 and a bypass line 1426. The first and second three-way valves 1414, 1416 are connected by a bypass line on which a third solenoid valve 1406 is positioned. A third three-way valve 1418 is positioned at a junction between the line 126, the bypass line 1426, and a bypass line on which a second solenoid valve 1404 is positioned. A fourth three-way valve 1420 is positioned at a junction between the line 122, the bypass line on which the second solenoid valve 1404 is positioned, and a bypass line on which a fourth solenoid valve 1408 is positioned. A fifth three-way valve 1422 is positioned at a junction between the line 128, the line 124, and the bypass line on which the fourth solenoid valve 1408 is positioned. A sixth three-way valve 1424 is positioned at a junction between the line 118, the line 124, and a bypass line on which a sixth solenoid valve 1412 is positioned. A first solenoid valve 1403 is positioned on the line 124 proximate the sixth three-way valve 1424. A fifth solenoid valve 1410 is positioned on the bypass line 1426, between the second and third three-way valves 1416, 1418.

[0109] Referring to FIG. 14, in a space heating mode of the heat pump 1402, each of the indoor fan 76 and the outdoor fan 78 are operated to force the respective air streams 80, 82 across the coils. The indoor heat exchanger 68 operates as the condenser, heating the inlet air stream 80, and the outdoor heat exchanger 70 operates as the evaporator, absorbing heat from the outdoor air stream 82. The first reversing valve 106 is in the first position, and the network of valves 1407 are positioned to direct the working fluid through the loop 1405 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 116 towards and through the sixth three-way valve 1424, into the sixth solenoid valve bypass line, through the sixth solenoid valve 1412 and the first three-way valve 1414, into the line 122 towards and through the WRHX 36, through the fourth three-way valve 1420 and into the fourth solenoid valve bypass line, through the fourth solenoid valve 1420 and the fifth three-way valve 1422, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and through the expansion device 20, into the bypass line 1426 through the fifth solenoid valve 1410, through the second three-way valve 1416, into the line 120 towards and through the outdoor heat exchanger 70, into the line 114 and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the space heating mode of FIG. 14, each of the first solenoid valve 1403, the second solenoid valve 1404, and the third solenoid valve 1406 are closed, which isolates the lines on which these solenoid valves are positioned.

[0110] In both the space heating mode of FIG. 14, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0111] FIG. 15 depicts the system 1400 in a defrost mode, similar to the defrost mode described above for the system 900 with reference to FIG. 11. As described above, during space heating, the heat pump 1402 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, the first reversing valve 106 is in the second position, and the network of valves 1407 has the same position as the space heating mode of FIG. 14. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The network of valves 1407 enable the working fluid to flow through the same lines of the loop 1405 as described above with reference to FIG. 14, and the first reversing valve 106 in the second position directs the working fluid to flow in the opposite direction relative to the space heating mode of FIG. 14.

[0112] In the defrost mode of FIG. 15, as described above for the defrost mode of FIG. 11, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 1402 is in the defrost mode as described above with reference to FIG. 6 and FIG. 11. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIG. 6 and FIG. 11, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0113] The system 1400 is operable in other operating modes than those shown in FIGS. 14 and 15 and described above. For example, the system 1400 is operable in a space cooling and water heating mode, as shown in FIG. 9, a thermosiphon space heating mode, as shown in FIG. 12, and a dedicated water heating mode, as shown in FIG. 4. In the space cooling mode of the system 1400, the first solenoid valve 1403, the second solenoid valve 1404, and the third solenoid valve 1406 are closed, and each of the fourth solenoid valve 1408, the fifth solenoid valve 1410, and the sixth solenoid valve 1412 are energized (open). In the thermosiphon space heating mode of the system 1400, the first solenoid valve 1403, the second solenoid valve 1404, and the sixth solenoid valve 1412 are closed, each of the third solenoid valve 1406, the fourth solenoid valve 1408, and the fifth solenoid valve 1410 are energized (open), and the expansion device 20 is fully open (or bypassed). In some examples, the system 1400 is also operable in a space heating only mode or a space cooling only mode. In the space heating only and space cooling only operating modes, the heat pump 1402 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). In some examples, the system 1400 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 1402 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 1402 demand, as described above.

[0114] Description of the controller 64 with reference to FIGS. 1-13 applies to the controller 64 of the system 1400 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 1400 using the control algorithms shown in FIGS. 5-8 and 13 and described above.

[0115] Table 1 below provides a summary of example operating modes of the system 1400, the positioning of the first reversing valve 106 and the solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 in each operating mode, and the components of the system 1400 that are operated in each mode.TABLE 1Overview of Control of the System 1400 of FIGS. 14 and 15Task ScenarioLocationJob / Energy SourceMitigationSpaceDefrostIntDeviceSpaceSpaceHeatingDefrostOD CoilWaterIndependentControlCoolingHeatingw / HotOD Coilw / HotHeatingWaterMitigationSystem Operating Modesw / DXw / DXWaterw / DXWaterw / DXHeatingDevice1Space Cooling Only✓2Space Cooling + Partial✓✓✓Preheating Cold Water Supply3Space Cooling + Preheating✓✓Cold Water Supply4Space Cooling + Standby Water✓✓Heating5Space Heating Only✓6Space Heating + Preheating✓✓Cold Water Supply7Space Heating + Standby Tank✓✓Water Heating8Space Heating: HP + Hydronic✓✓Refr Heating9Hydronic Thermosiphon Space✓Heating10Defrost of Outdoor Coil Using✓✓HP + Water to Heat Refrigerant11Defrost of Outdoor Coil Using✓HP12Dedicated Water Heating:✓Preheating Cold Water Supply13Dedicated Water Heating:✓Standby Tank using HP14Dedicated Water Heating:✓Standby TankTABLE 1Overview of Control of the System 1400 of FIGS. 14 and 15Mitigation OptionsINDOORSOUTDOORSHot WaterTstat / TankTstat / FurnaceTstat / ControllerTstat / FurnaceBoard +FurnaceSecondary IWH Kit ControllerWaterFurnaceBoardOD FanBoardSole-Sole-Sole-Sole-Sole-Sole-TankBoardRevers-ControlIndoornoidnoidnoidnoidnoidnoidWaterSupp HeatCom-ingOutdoorBlowerValve 1Valve 2Valve 3Valve 4Valve 5Valve 6EXVPumpSourcepressorValveFanONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1ON% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFONONPos 1ON% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1CYC% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDONOFFONPos 1CYC% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENONCLOSEDCLOSEDOPENOPENOPENCLOSEDFULL OPENONOFFOFFPos 1OFFOFFOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDONOFFONPos 1OFF% OPENOFFOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1OFF% OPENOFFCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENOFFCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENOFFCLOSEDCLOSEDCLOSEDCLOSEDCLOSEDCLOSEDN / AOFFONOFFPos 1OFFFIGS. 16-19 depict a fourth example of an integrated heat pump-water heater system 1600 that includes a heat pump 1602 operable in multiple operating modes and the water heater 14 integrated with the heat pump 1602. The heat pump 1602 includes similar elements and components as the heat pump 12 of FIG. 1 and the heat pump 102 of FIGS. 2-4, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4.

[0117] In this example, the system 1600 includes the first reversing valve 106 on the loop, without a network of valves connected to the first reversing valve 106. The first reversing valve 106 is positionable to reverse the direction of flow of working fluid through a working fluid loop 1605. The lines of the working fluid loop 1605 are consolidated in this example, similar to FIG. 1. The WRHX 36 is positioned on the line 116, which connects the first reversing valve 106 and the indoor heat exchanger 68. The expansion device 20 is positioned on the line 120, which connects the indoor heat exchanger 68 and the outdoor heat exchanger 70.

[0118] FIG. 16 depicts the system 1600 in a space heating mode. The first reversing valve 106 is in the first position, the indoor heat exchanger68 is operated as the condenser, and the outdoor heat exchanger 70 is operated as the evaporator. The first reversing valve 106 in the first position directs the working fluid exiting the compressor 72 via the line 112 into the line 116 and through the WRHX 36. The working fluid then flows through the indoor exchanger 68, into the line 120, through the expansion device 20, towards and through the outdoor heat exchanger 70, into the line 114 and through the reversing valve 106, into the suction line 118 towards the compressor 72. In the space heating mode of the heat pump 1602, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0119] FIG. 17 depicts the system 1600 in a dedicated water heating mode, similar to FIG. 4. As described above, the system 1600 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58 and / or to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the first reversing valve 106 is in the first position and the working fluid flows as described above for the space heating mode of FIG. 16. The outdoor heat exchanger 70 is operated as the evaporator, as described above for the space heating mode of FIG. 16. The indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 1602. The water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0120] FIG. 18 depicts the system 1600 in a space cooling only mode. The first reversing valve 106 is in the second position, the indoor heat exchanger 68 is operated as the evaporator, and the outdoor heat exchanger 70 is operated as the condenser. The first reversing valve 106 in the second position directs the working fluid in the opposite direction through the loop 1605 as the space heating mode of FIG. 16. The working fluid exiting the compressor 72 via the line 112 is directed by the first reversing valve 106 into the line 114 and through the outdoor heat exchanger 70. The working fluid then flows into the line 120, through the expansion device 20, towards and through the indoor heat exchanger 68, into the line 116 towards and successively through the WRHX 36 and the reversing valve 106, into the suction line 118 towards the compressor 72. In the space cooling only mode, little to no heat is transferred in the WRHX 36, and the water heater 14 is controlled by the controller 64 to not flow water through the loop 34.

[0121] FIG. 19 depicts the system 1600 in a defrost mode. As described above, during space heating, the heat pump 1602 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, and the first reversing valve 106 is in the second position. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The reversing valve 106 in the second position directs the working fluid through the loop 905 as described above for the space cooling mode of FIG. 18.

[0122] In the defrost mode of FIG. 19, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 1602 is in the defrost mode as described above with reference to FIGS. 6 and 11. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIGS. 6 and 11, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0123] The system 1600 is operable in other operating modes than those shown in FIGS. 16-19 and described above. For example, the system 1600 is operable in a space heating only mode in which, like the space cooling only mode of FIG. 18, the heat pump 1602 conditions the inlet air stream 80 while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). In some examples, the system 1600 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 1602 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 1602 demand, as described above.

[0124] Description of the controller 64 above applies to the controller 64 of the system 1600 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 1600 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to exclude any operations related to control of a network of valves that is not included in the system 1600 and the functionality that the network of valves provides. For example, in the system 1600, water heating may not be available when the heat pump 1602 is in a space cooling mode. As such, referring to FIG. 7, the controller 64 may not perform operations 714-720 for the system 1600, and instead may always operate the water pump 56 in an idle or off state when the system 1600 is in the space cooling mode.

[0125] FIGS. 20-22 depict a fifth example of an integrated heat pump-water heater system 2000 that includes a heat pump 2002 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2002. The heat pump 2002 includes similar elements and components as the heat pump 12 of FIG. 1, the heat pump 102 of FIGS. 2-4, and the heat pump 1602 of FIGS. 16-19, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4 and FIGS. 16-19.

[0126] In this example, the system 2000 includes the first reversing valve 106 and a network of valves 2007 on a working fluid loop 2005 of the heat pump 2002 to control flow of a working fluid (e.g., refrigerant) through the loop 2005. The network of valves 2007 is connected to the first reversing valve 106 and includes a first three-way valve 2004 positioned on the line 120 and a second three-way valve 2006 positioned on the line 116. The first and second three-way valves 2004, 2006 are connected by a bypass line 2008. The WRHX 36 is positioned on the line 116 between the bypass line 2008 and the indoor heat exchanger 68.

[0127] FIG. 20 depicts the system 2000 in a space heating mode. The first reversing valve 106 is in the first position, the indoor heat exchanger 68 is operated as the condenser, and the outdoor heat exchanger 70 is operated as the evaporator. The first reversing valve 106 in the first position directs the working fluid through the loop as described above for FIG. 16. The first and second three-way valves 2004, 2006 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 116 or line 120 into the bypass line 2008.

[0128] In the space heating mode of the heat pump 2002, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0129] FIG. 21 depicts the system 2000 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 2004, 2006 and the bypass line 2008. The thermosiphon space heating mode is similar to that described above for FIG. 12. In the thermosiphon space heating mode, the outdoor components of the heat pump 2002, including the compressor 72 and the outdoor fan 78, are idle. The network of valves 2007 is operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 2002. To enable a thermosiphon or compressor-free mode of the heat pump 2002, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 2005 using natural convection rather than by mechanical force. The system 2005 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0130] In the thermosiphon or compressor-free mode of FIG. 21, each of the three-way valves 2004, 2006 is in a second (bypass) position to allow the working fluid to flow through the bypass line 2008 between the lines 116 and 120. The three-way valves 2004, 2006 in the second position restrict flow of the working fluid in the lines 116, 120 to within a portion between the indoor heat exchanger 68 and the valves 2004, 2006. As such, the lines 112, 114, and 118, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2005. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 21, in the thermosiphon or compressor-free mode, the three-way valves 2004, 2006 direct the working fluid through the loop 2005 as follows: working fluid flows through the line 116 and the WRHX 36, towards and through the indoor heat exchanger 68, into the line 120 towards and successively through the expansion device 20 and the first three-way valve 2004, into the bypass line 2008 towards and through the second three-way valve 2006, and back into the line 116. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2005 by natural convection.

[0131] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 21 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0132] FIG. 22 depicts the system 2000 in a space cooling only mode. The first reversing valve 106 is in the second position, the indoor heat exchanger 68 is operated as the evaporator, and the outdoor heat exchanger 70 is operated as the condenser. The first reversing valve 106 in the second position directs the working fluid in the opposite direction through the loop 2005 as the space heating mode of FIG. 20, and in the flow direction as described above for FIG. 18. The first and second three-way valves 2004, 2006 are each in the first (non-bypass) position, such that the working fluid is not redirected from either line 116 or line 120 into the bypass line 2008. In the space cooling only mode, little to no heat is transferred in the WRHX 36, and the water heater 14 is controlled by the controller 64 to not flow water through the loop 34.

[0133] The system 2000 is operable in other operating modes than those shown in FIGS. 20-22 and described above. For example, the system 2000 is operable in a space heating only mode in which, like the space cooling only mode of FIG. 22, the heat pump 2002 conditions the inlet air stream 80 while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). The system 900 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 2002 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 2002 demand, as described above.

[0134] Description of the controller 64 above applies to the controller 64 of the system 2000 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2000 using the control algorithms shown in FIGS. 5-8 and 13 and described above, which may be modified as appropriate related to control of the network of valves 2007, specifically the three-way valves 2004, 2006 and the functionality that the network of valves provides. Referring to FIG. 13, the controller 64 determines whether to operate the system 2000 in the space heating mode of FIG. 20 or the thermosiphon space heating mode based the determinations at 1304 and 1322. In the system 2000, water heating may not be available when the heat pump 2002 is in a space cooling mode. As such, referring to FIG. 7, the controller 64 may not perform operations 714-720 for the system 2000, and instead may always operate the water pump 56 in an idle or off state when the system 2000 is in the space cooling mode.

[0135] FIG. 23 depicts a sixth example of an integrated heat pump-water heater system 2300 that includes a heat pump 2302 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2302. The heat pump 2302 includes similar elements and components as the heat pump 12 of FIG. 1, the heat pump 102 of FIGS. 2-4, the heat pump 1602 of FIGS. 16-19, and the heat pump 2002 of FIGS. 20-22, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4 and FIGS. 16-22.

[0136] In this example, the system 2300 includes the first reversing valve 106 and a network of valves 2307 on a working fluid loop 2305 of the heat pump 2302 to control flow of a working fluid (e.g., refrigerant) through the loop 2305. The network of valves 2007 is connected to the first reversing valve 106 and includes three solenoid valves 2304, 2306, and 2308, which are operable to provide similar functionality as the first three-way valve 2004 and the second three-way valve 2006 of the system 2000 of FIGS. 20-22. A first solenoid valve 2304 is positioned on the line 116 between the first reversing valve 106 and the bypass line 2008. A second solenoid valve 2306 is positioned on the line 120 between the outdoor heat exchanger 70 and the bypass line 2008. A third solenoid valve 2308 is positioned on the bypass line 2008. Similar to the system 2000, in this example, the WRHX 36 is positioned on the line 116, between the bypass line 2008 and the indoor heat exchanger 68.

[0137] The system 2300 operates similar to the system 2000. For example, the system 2300 is operable in a space heating mode (shown in FIG. 23) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space heating mode of FIG. 23, the first reversing valve 106 is in the first position and each of the first and second solenoid valves 2304, 2306 are energized to allow the working fluid to flow through the loop 2305 as described above for FIG. 20, and the third solenoid valve 2308 is de-energized or off to prevent flow of the working fluid through the bypass line 2008. In the space heating mode of FIG. 23, the water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36.

[0138] The system 2300 is operable in the other operating modes described above for the system 2000 of FIGS. 20-22. For example, the system 2300 is operable in a thermosiphon space heating mode, a space cooling only mode, a space heating only mode, and in a space heating / cooling and hydronic heating mode. Description of the controller 64 above with reference to the system 2000 applies to the controller 64 of the system 2300 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2300 using similar control algorithms as used to control the system 2000, shown in FIGS. 5-8 and 13 and described above, which may be modified as appropriate to control the solenoid valves 2304, 2306, 2308 in a similar manner as the three-way valves 2004, 2006.

[0139] In the thermosiphon space heating mode of the system 2300, the third solenoid valve 2308 is energized to allow the working fluid to flow through the bypass line 2008 between the lines 116 and 120. The first and second solenoid valves 2304, 2306 are de-energized (off or closed) to restrict flow of the working fluid in the lines 116, 120 to within a portion between the indoor heat exchanger 68 and the valves 2004, 2006, and isolate the lines 112, 114, and 118, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 2304, 2306, 2308 are operated to direct the working fluid through the loop 2305 as described above with reference to FIG. 21. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2305 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 21.

[0140] FIGS. 24-26 depict a seventh example of an integrated heat pump-water heater system 2400 that includes a heat pump 2402 operable in a space cooling mode and the water heater 14 integrated with the heat pump 2402. In this example, the system 2400 is operable in a space cooling and standby water heating mode (FIG. 24), a space cooling and groundwater heating mode (FIG. 25), and a space cooling only mode (FIG. 26). The heat pump 2402 does not include the first reversing valve 106 or a network of valves in this example, and is configured similar to the heat pump 12 of FIG. 1, except that the WRHX 36 and the expansion device 20 are on a common line 2404 of a working fluid loop 2405 that extends between the indoor heat exchanger 68 and the outdoor heat exchanger 70. The expansion device 20 is positioned between the WRHX 36 and the indoor heat exchanger 68. The working fluid loop 2405 also includes a suction line 2406 extending between the indoor heat exchanger 68 and the compressor 72, and a discharge line 2408 extending between the compressor 72 and the outdoor heat exchanger 70. In this example, the suction line accumulator 74 is positioned indoors on the suction line 2406, upstream from the compressor 72. The compressor 72 and the outdoor heat exchanger 70 are each positioned outdoors, and the lines 2404, 2406 extend through the partition 11.

[0141] In each space cooling mode of FIGS. 24-26, the working fluid exiting the compressor 72 flows through the discharge line 2408 towards and through the outdoor heat exchanger 70, into the line 2404 towards and successively through the WRHX 36 and the expansion device 20, through the indoor heat exchanger 68 and into the suction line 2406 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 2402 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80.

[0142] Description of the controller 64 above applies to the controller 64 of the system 2400 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2400 using the control algorithms shown in FIGS. 5 and 7 and described above, which may be modified as appropriate to exclude any operations related to control of a reversing valve and a network of valves that is not included in the system 2400 and the functionality that the reversing valve and the network of valves provide. The system 2400 does not operate in a space heating mode or a dedicated water heating mode, and as such, the control algorithms of FIGS. 6 and 8 are not implemented in this example. The system 900 may be operable in a space cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 2402 via the WRHX 36 in the space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 2402 demand, as described above.

[0143] In the space cooling mode of FIGS. 24-26, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 24), the groundwater heating mode (FIG. 25), or neither (FIG. 26, in which the system 2400 provides space cooling only). Referring to FIGS. 7 and 24, the controller 64 may operate the water heater 14 in the standby water heating mode and / or the groundwater heating mode when the controller 64 determines at 712 that there is a need for water heating in the water heater 14. In response, the water pump 56 is controlled to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and the three-way valves 42, 44 are positioned to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26 and / or the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. If the controller 64 determines at 712 that there is not a need for water heating in the water heater 14, the controller 64 can operate the water heater 14 in the groundwater heating mode. Alternatively, the controller 64 may control the water heater 14 to not flow water through the loop 34, such that the system 2400 is in the space cooling only mode. The space cooling only mode may be appropriate, for example, when the controller 64 determines that there is a demand for additional cooling of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is above a setpoint temperature), and the controller 64 determines that there is no availability for using the working fluid in the loop 2405 to heat water in the loop 34 via the WRHX 36.

[0144] The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 2400, depending on the ambient conditions as measured by the sensor 136. As described above, in the space cooling mode, the ability of the working fluid to transfer heat into the water in the loop 34 varies based on the outside temperature conditions, which affect the amount of heat transfer that occurs between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70. Smaller heat transfer in the outdoor heat exchanger 70, which is more likely to occur in hot temperature outside conditions, provides more capability of the working fluid in the line 122 to reject heat into the water loop 34 via the WRHX 36. Referring to FIG. 7, the controller 64 monitors at 716 the ability of the working fluid exiting the outdoor heat exchanger 70 to transfer heat into the water in the loop 34 via the WRHX 36 during the water heating operation initiated at 714. For example, the controller 64 monitors 716 the temperature of the working fluid exiting the outdoor heat exchanger 70 in the line 2404 via the sensor 130. Additionally, or alternatively, the controller 64 may monitor 716 any suitable operating condition of the heat pump 2402 indicative of the ability of the working fluid to transfer heat via the WRHX while the heat pump 2402 is in the space cooling mode. For example, the controller 64 monitors 716 the ambient temperature via the sensor 136 and / or a temperature of the working fluid in the 122 upstream from the WRHX 36. At 718, the controller 64 determines whether the monitored 716 condition satisfies a predetermined criterion that is indicative of effective heat transfer between the working fluid in the line 2404 and the water in the loop 34 via the WRHX 36. For example, the controller 64 determines whether the monitored 716 temperature of the working fluid in the line 2404 exiting the outdoor heat exchanger 70 meets or exceeds a predetermined temperature value (e.g., 130° F.) that is indicative of effective heat transfer. If the monitored 716 condition (e.g., temperature) meets or exceeds the predetermined criterion (e.g., the predetermined value), the controller 64 takes no further action and allows operation to continue. If the monitored 716 condition (e.g., temperature) is below the predetermined criterion (e.g., the predetermined temperature value), the controller 64 may cycle, bypass, and / or operate as idle the outdoor fan 78 at 720.

[0145] FIGS. 27-30 depict an eighth example of an integrated heat pump-water heater system 2700 that includes a heat pump 2702 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2702. The heat pump 2702 includes similar elements and components as the heat pump 2402 of FIGS. 24-26, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0146] In this example, in addition to the elements and components of the system 2400 of FIGS. 24-26, the system 2700 includes two three-way valves 2704, 2706 on a working fluid loop 2705 of the heat pump 2702 to control flow of a working fluid (e.g., refrigerant) through the loop 2705. The three-way valves 2704, 2706 provide additional functionality to the integrated system 2700 relative to the system 2400 of FIGS. 24-26. A first three-way valve 2704 is positioned on the line 2404 between the outdoor heat exchanger 70 and the WRHX 36. A second three-way valve 2706 is positioned on the suction line 2406 between the indoor heat exchanger 68 and the suction line accumulator 74. The first and second three-way valves 2704, 2706 are connected by a bypass line 2708.

[0147] FIGS. 27-29 depict the system 2700 in a space cooling mode, similar to the modes of FIGS. 24-26. As described above for each space cooling mode of FIGS. 24-26, in the space cooling mode of FIGS. 27-29, the working fluid exiting the compressor 72 flows through the discharge line 2408 towards and through the outdoor heat exchanger 70, into the line 2404 towards and successively through the WRHX 36 and the expansion device 20, through the indoor heat exchanger 68 and into the suction line 2406 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 2402 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80. The first and second three-way valves 2704, 2706 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 2404 or line 2406 into the bypass line 2708.

[0148] Description of the controller 64 above and the functions executed by the controller 64 for the space cooling modes of FIGS. 24-26 applies to the controller 64 of the system 2700. For example, in the space cooling mode of FIGS. 27-29, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 27), the groundwater heating mode (FIG. 28), or neither (FIG. 29, in which the system 2700 provides space cooling only) as described above. The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 2700, depending on the ambient conditions as measured by the sensor 136 as described above.

[0149] FIG. 30 depicts the system 2700 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 2704, 2706 and the bypass line 2708. The thermosiphon space heating mode is similar to that described above for FIGS. 12 and 21. In the thermosiphon space heating mode, the outdoor components of the heat pump 2702, including the compressor 72 and the outdoor fan 78, are idle. The three-way valves 2704, 2706 are operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 2702. To enable a thermosiphon or compressor-free mode of the heat pump 2702, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 2705 using natural convection rather than by mechanical force. The system 2700 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0150] In the thermosiphon or compressor-free mode of FIG. 30, each of the three-way valves 2704, 2706 is in a second (bypass) position to allow the working fluid to flow through the bypass line 2708 between the lines 2404 and 2406. The three-way valves 2704, 2706 in the second position restrict flow of the working fluid in the lines 2404, 2406 to within a portion between the indoor heat exchanger 68 and the valves 2704, 2706. As such, the line 2408, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2705. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 30, in the thermosiphon or compressor-free mode, the three-way valves 2704, 2706 direct the working fluid through the loop 2705 as follows: working fluid flows through the portion of the line 2404 between the first three-way valve 2704 and the indoor heat exchanger 68, successively through the WRHX 36, the expansion device 20, and the indoor heat exchanger 68, into the line 2406 towards and through the second three-way valve 2706, into the bypass line 2708 towards and through the first three-way valve 2704, and back into the line 2404. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2705 by natural convection.

[0151] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 30 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0152] The controller 64 also determines whether to operate the system 2700 in the thermosiphon space heating mode of FIG. 30 based on the outside conditions and whether hot water is available in the water heater 14 for heating the working fluid in the loop 2705. This can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 30 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 2700 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 30 (e.g., at 1322 of FIG. 13), then the controller 64 does not initiate the thermosiphon space heating mode. In this example, the system 2700 may operate in conjunction with another heating source that supplies heat to the indoor space when a space heating mode is requested and the thermosiphon space heating mode of FIG. 30 is not available.

[0153] FIG. 31 depicts a ninth example of an integrated heat pump-water heater system 3100 that includes a heat pump 3102 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3102. The heat pump 3102 includes similar elements and components as the heat pump 2702 of FIGS. 27-30, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 27-30. In this example, the system 3100 includes three solenoid valves 3104, 3106, and 3108, which are operable to provide similar functionality as the three-way valves 2704, 2706 of the system 2700 of FIGS. 27-30. A first solenoid valve 3104 is positioned on the line 2404 between the outdoor heat exchanger 70 and the bypass line 2708. A second solenoid valve 3106 is positioned on the suction line 2406 between the outdoor heat exchanger 70 and the bypass line 2708. A third solenoid valve 3108 is positioned on the bypass line 2708. Similar to the system 2700, in this example, the WRHX 36 is positioned on the line 2404, between the bypass line 2708 and the indoor heat exchanger 68.

[0154] The system 3100 operates similar to the system 2700. For example, the system 3100 is operable in a space cooling mode in conjunction with standby water heating (shown in FIG. 31) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space cooling and standby water heating mode of FIG. 31, each of the first and second solenoid valves 3104, 3106 are energized to allow the working fluid to flow through the loop 3105 as described above for FIGS. 27-29, and the third solenoid valve 3108 is de-energized or off to prevent flow of the working fluid through the bypass line 2708. In the space cooling mode of the system 3100, the controller 64 operates the water heater 14 as described above for FIGS. 27-29, in a standby water heating mode (FIG. 31), the groundwater heating mode (similar to FIG. 28), or neither (similar to FIG. 29, in which the system 3100 provides space cooling only). The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 3100, depending on the ambient conditions as measured by the sensor 136 as described above.

[0155] The system 3100 is operable in a thermosiphon space heating mode, similar to the thermosiphon space heating mode of the system 2700 shown in FIG. 30. In the thermosiphon space heating mode of the system 3100, the third solenoid valve 3108 is energized to allow the working fluid to flow through the bypass line 2708 between the lines 2404 and 2406. The first and second solenoid valves 3104, 3106 are de-energized (off or closed) to restrict flow of the working fluid in the lines 2404, 2406 to within the portion between the indoor heat exchanger 68 and the valves 3104, 3106, and isolate the line 2408, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 3104, 3106, 3108 are operated to direct the working fluid through the loop 3105 as described above with reference to FIG. 30. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3105 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 30.

[0156] Description of the controller 64 above with reference to the system 2700 applies to the controller 64 of the system 3100 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3100 using similar control algorithms as used to control the system 2700, which may be modified as appropriate to control the solenoid valves 3104, 3106, 3108 in a similar manner as the three-way valves 2704, 2706.

[0157] FIGS. 32-34 depict a tenth example of an integrated heat pump-water heater system 3200 that includes a heat pump 3202 operable in a space heating mode and the water heater 14 integrated with the heat pump 3202. In this example, the system 3200 is operable in a space cooling and standby water heating mode (FIG. 32), a space cooling and groundwater water heating mode (not shown), a dedicated water heating mode (FIG. 33), and a space heating only mode (FIG. 34). The heat pump 3202 does not include the first reversing valve 106 or a network of valves in this example, and is configured similar to the heat pump 2402 of FIGS. 24-26, except that the WRHX 36 and the expansion device 20 are on a different lines of a working fluid loop 3205. The WRHX 36 is positioned on a discharge line 3210 that extends from the compressor 72 to the indoor heat exchanger 68. The expansion device 20 is positioned on a line 3204 that extends the indoor heat exchanger 68 and the outdoor heat exchanger 70. The working fluid loop 3205 also includes a suction line 3206 extending between the outdoor heat exchanger 70 and the compressor 72. In this example, the accumulator 74 is positioned indoors on the line 3204, upstream from the outdoor heat exchanger 70. The compressor 72 and the outdoor heat exchanger 70 are each positioned outdoors, and the lines 3204, 3210 extend through the partition 11.

[0158] In each operating mode of the system 3200, such as those shown in FIGS. 32-34, the working fluid exiting the compressor 72 flows through the discharge line 3210 towards and successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, and into the suction line 3206 back towards the compressor 72. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3202 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. The indoor heat exchanger 68 operates as the condenser of the heat pump 3202 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80.

[0159] Description of the controller 64 above applies to the controller 64 of the system 3200 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3200 using the control algorithms shown in FIGS. 5, 6, and 8 and described above, which may be modified as appropriate to exclude any operations related to control of a reversing valve and a network of valves that is not included in the system 3200 and the functionality that the reversing valve and the network of valves provide. The system 3200 does not operate in a space cooling mode, and as such, the control algorithm of FIG. 7 is not implemented in this example.

[0160] In the space heating mode of the heat pump 3202, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 32), the groundwater heating mode (not shown), or neither (FIG. 34, in which the system 3200 provides space heating only). Referring to FIGS. 6 and 32, the controller 64 may operate the water heater 14 in the standby water heating mode (or the groundwater heating mode) when the controller 64 determines at 628 that there is not a demand for additional heating of the inlet air stream 80 and at 630 that there is a need for water heating in the water heater 14. In response, the water pump 56 is controlled to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and the three-way valves 42, 44 are positioned to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26, and / or the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. If the controller 64 determines at 628, and / or at 636, that there is a demand for additional heating of the inlet air stream 80, and that heating of the water using the working fluid via the WRHX 36 is not available, the controller 64 controls the water heater 14 to not flow water through the loop 34, such that the system 3200 is in the space heating only mode. The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 3202 in the space heating mode via the WRHX 36 when conditions in the water heater 14 allow and conditions in the heat pump 3202 demand, as described above.

[0161] FIG. 33 depicts the system 3200 in a dedicated water heating mode, which can be initiated by the controller 64 according to the control algorithm of FIG. 8 (e.g., when the heat pump 3202 is not being used to condition the inlet air stream 80 and the controller 64 determines that there is a need for water heating in the water heater 14). As described above, for example with reference to FIG. 4, the system 3200 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58 and / or to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the working fluid flow through the loop 3205 as described above for FIGS. 32 and 34. The outdoor heat exchanger 70 is operated as the evaporator, and the indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 3202. The water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0162] FIGS. 35-37 depict an eleventh example of an integrated heat pump-water heater system 3500 that includes a heat pump 3502 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3502. The heat pump 3502 includes similar elements and components as the heat pump 3200 of FIGS. 32-34, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0163] In this example, in addition to the elements and components of the system 3200 of FIGS. 32-34, the system 3500 includes two three-way valves 3504, 3506 on a working fluid loop 3505 of the heat pump 3505 to control flow of a working fluid (e.g., refrigerant) through the loop 3505. The three-way valves 3504, 3506 provide additional functionality to the integrated system 3500 relative to the system 3200 of FIGS. 32-34. A first three-way valve 3504 is positioned on the discharge line 3210 between the compressor 72 and the WRHX 36. A second three-way valve 3506 is positioned on the line 3204 between the indoor heat exchanger 68 and the expansion device 20. The first and second three-way valves 3504, 3506 are connected by a bypass line 3508.

[0164] FIGS. 35 and 36 depict the system 3500 in a space heating and standby water heating mode and a dedicated water heating mode, respectively, similar to the modes of FIGS. 32 and 33. As described above for each operating mode of FIGS. 35-37, in the space heating mode of FIG. 32 and the dedicated water heating mode of FIG. 33, the working fluid exiting the compressor 72 flows through the discharge line 3210 towards and successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, and into the suction line 3206 back towards the compressor 72. The first and second three-way valves 3504, 3506 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 3204 or line 3210 into the bypass line 3508. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3202 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. In the space heating mode, the indoor heat exchanger 68 operates as the condenser of the heat pump 3202 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. In the dedicated water heating mode, the indoor fan 76 is idle or off, and the WRHX 36 may operate as the condenser.

[0165] Description of the controller 64 above and the functions executed by the controller 64 for the space heating modes and dedicated water heating mode of FIGS. 32-34 for the system 3200 applies to the controller 64 of the system 3500. For example, in the space heating mode of the heat pump 3502, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 35), the groundwater heating mode, or neither (in which the system 3500 provides space heating only) as described above. Additionally, the controller 64 may initiate hydronic (water-to-working fluid) heating to supplement the heat pump 3502 in the space heating mode via the WRHX 36 using water in the water loop 34 when conditions in the water heater 14 allow and conditions in the heat pump 3502 demand, as described above.

[0166] FIG. 37 depicts the system 3500 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 3504, 3506 and the bypass line 3508. The thermosiphon space heating mode is similar to that described above for FIGS. 12, 21, and 30. In the thermosiphon space heating mode, the outdoor components of the heat pump 3502, including the compressor 72 and the outdoor fan 78, are idle. The three-way valves 3504, 3506 are operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 3502. To enable a thermosiphon or compressor-free mode of the heat pump 3502, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 3505 using natural convection rather than by mechanical force. The system 3505 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0167] In the thermosiphon or compressor-free mode of FIG. 37, each of the three-way valves 3504, 3506 is in a second (bypass) position to allow the working fluid to flow through the bypass line 3508 between the lines 3204 and 3210. The three-way valves 3504, 3506 in the second position restrict flow of the working fluid in the lines 3204, 3210 to within a portion between the indoor heat exchanger 68 and the valves 3504, 3506. As such, the line 3206, the expansion device 20, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2705. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 37, in the thermosiphon or compressor-free mode, the three-way valves 3504, 3506 direct the working fluid through the loop 3505 as follows: working fluid flows through the portion of the line 3210 between the first three-way valve 3504 and the indoor heat exchanger 68, successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and through the second three-way valve 3506, into the bypass line 3508 towards and through the first three-way valve 3504, and back into the line 3210. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3505 by natural convection.

[0168] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 37 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0169] The controller 64 also determines whether to operate the system 3500 in the thermosiphon space heating mode of FIG. 37 based on the outside conditions and whether hot water is available in the water heater 14 for heating the working fluid in the loop 3505. This can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 37 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 3500 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 37 (e.g., at 1322 of FIG. 13), then the controller 64 initiates the space heating mode of the heat pump 3502 using the outdoor heat exchanger 70 as the evaporator (e.g., as shown in FIG. 35).

[0170] FIG. 38 depicts a twelfth example of an integrated heat pump-water heater system 3800 that includes a heat pump 3802 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3802. The heat pump 3802 includes similar elements and components as the heat pump 3802 of FIGS. 35-37, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 35-37. In this example, the system 3800 includes three solenoid valves 3804, 3806, and 3808, which are operable to provide similar functionality as the three-way valves 3504, 3506 of the system 3500 of FIGS. 35-37. A first solenoid valve 3804 is positioned on the discharge line 3210 between the compressor 72 and the bypass line 3508. A second solenoid valve 3806 is positioned on the line 3204 between the expansion device 20 and the bypass line 3508. A third solenoid valve 3808 is positioned on the bypass line 3508. Similar to the system 3500, in this example, the WRHX 36 is positioned on the discharge line 3210, between the bypass line 3508 and the indoor heat exchanger 68.

[0171] The system 3800 operates similar to the system 3500. For example, the system 3800 is operable in a space heating mode in conjunction with standby water heating (shown in FIG. 38) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space heating and standby water heating mode of FIG. 38, each of the first and second solenoid valves 3804, 3806 are energized to allow the working fluid to flow through the loop 3805 as described above for FIGS. 35-37, and the third solenoid valve 3808 is de-energized or off to prevent flow of the working fluid through the bypass line 3508. The controller 64 operates the water heater 14 in conjunction with the space heating mode of the heat pump 3802, as described above for the system 3500, in the standby water heating mode, the groundwater heating mode, or no water heating (in which the system 3800 provides space cooling only). The system 3800 is also operable in a dedicated water heating mode, similar to the dedicated water heating mode of FIG. 36, a thermosiphon space heating mode, similar to the thermosiphon space heating mode of FIG. 37, and a space heating and hydronic heating mode.

[0172] In the thermosiphon space heating mode of the system 3800, the third solenoid valve 3808 is energized to allow the working fluid to flow through the bypass line 3508 between the lines 3204 and 3210. The first and second solenoid valves 3804, 3806 are de-energized (off or closed) to restrict flow of the working fluid in the lines 3204, 3210 to within the portion between the indoor heat exchanger 68 and the valves 3804, 3806, and isolate the line 3206, the expansion device 20, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 3804, 3806, 3808 are operated to direct the working fluid through the loop 3805 as described above with reference to FIG. 37. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3105 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 37.

[0173] Description of the controller 64 above with reference to the system 3500 applies to the controller 64 of the system 3800 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3800 using similar control algorithms as used to control the system 3500, which may be modified as appropriate to control the solenoid valves 3804, 3806, 3808 in a similar manner as the three-way valves 3504, 3506.

[0174] In the example systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800 described above, the water heater 14, including the WRHX 36, is positioned entirely indoors. FIGS. 39 and 40 depict a thirteenth example of an integrated heat pump-water heater system 3900 that includes a heat pump 3902 operable in multiple operating modes and a water heater 3930 integrated with the heat pump 3902. The heat pump 3902 includes similar elements and components as the heat pumps described above for the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800, with like elements and components indicated using like reference numerals. The water heater 3930 includes similar elements and components as the water heater 14 described above for the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800, with like elements and components indicated using like reference numerals.

[0175] The water heater 3930 includes a water heater skid 3932 that includes a water loop 3934 and the WRHX 36 positioned on the water loop 3934. In this example, the WRHX 36 is positioned outdoors to enable additional functionality described below. The lines 48, 50 of the water loop 3932 each extend through the partition 11. The remaining components of the water loop 3932, including the lines 28, 38, 40, and 46, the three-way valves 42, 44, 62, the check valves 54, the water pump 56, and the water tank 26 are each located indoors in the water heater skid 3932. The water heater 3930 also includes a sensor 3936 (e.g., a temperature sensor) positioned outdoors on the line 50 to measure a condition (e.g., temperature) of the water exiting the WRHX 36. Additionally, or alternatively, the sensor 3936 is positioned indoors on the line 50.

[0176] The heat pump 3902 includes a first reversing valve 3920 connected to the compressor 72 by a discharge line 3910, and a second reversing valve 3922 connected to the first reversing valve 3920 by a line 3906. The first reversing valve 3920 is connected to the WRHX 36 by a line 3916 and a line 3918. The second reversing valve 3922 is connected to the outdoor heat exchanger 70 by a line 3912 and the indoor heat exchanger 68 by a line 3904. A line 3908 connects the indoor heat exchanger 68 and the outdoor heat exchanger 70. The expansion device 20 is positioned on the line 3908.

[0177] The first reversing valve 3920 is operable (positionable) between a first position (FIG. 39) in which the WRHX 36 is connected via the lines 3916, 3918 to a working fluid loop 3905 and, specifically, the lines 3910, 3906, respectively, and a second position (FIG. 40) in which the WRHX 36 and the lines 3916, 3918 are isolated from the working fluid loop 3905. The first reversing valve 3920 is thus operable (positionable) to selectively connect the WRHX 36 to the working fluid loop 3905 and isolate the WRHX 36 from the working fluid loop 3905. Because the WRHX 36 is positioned outdoors in this example, even when the WRHX 36 is isolated from the working fluid loop 3905, the WRHX 36 can heat the water in the water loop 3934 by absorbing heat from the ambient environment (e.g., from humid outside air). For example, the WRHX 36 can operate as a condenser for the refrigerant in lines 3916 and 3918. The absorbed heat from the refrigerant in lines 3916 and 3918 to heat the water in lines 48 and 50.

[0178] The second reversing valve 3922 is operable (positionable) between a first position (FIGS. 39 and 40) and a second position (not shown) to reverse the flow direction of the working fluid in the loop 3905. The second reversing valve 3922 enables the heat pump 3902 to operate in a space heating mode (when the second reversing valve 3922 is in the first position) and a space cooling mode (when the second reversing valve 3922 is in the second position). In the first position, as shown in FIGS. 39 and 40, the second reversing valve 3922 directs the working fluid to flow, generally, from the compressor 72 via the lines 3910, 3906, into the line 3904 towards and through the indoor heat exchanger 68, into the line 3908 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. In the second position, the second reversing valve 3922 directs the working fluid to flow, generally, from the compressor 72 via the lines 3910, 3906, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72.

[0179] When the WRHX 36 is connected to the water loop 3905 via the first reversing valve 3920 in the first position, the water in the water loop 3934 can be heated in both the space heating mode and the space cooling mode of the heat pump 3902. In particular, the first reversing valve 3920 in the first position connects the discharge line 3910 to the line 3916, and the line 3918 to the line 3906 between the first reversing valve 3920 and the second reversing valve 3922. As such, in both the space heating mode and the space cooling mode, and irrespective of the position of second reversing valve 3922, the first reversing valve 3920 in the first position directs hot, compressed working fluid through the WRHX 36 to heat the water in the water loop 3934. To cycle water through the water loop 3934, continuously or periodically, the water heater 3930 is controlled by the controller 64 as described above.

[0180] Referring to FIG. 39, in a space heating and water heating mode of the system 3900, each of the first reversing valve 3920 and the second reversing valve 3922 are in the first position. As such, the working fluid flows through the working fluid loop 3905 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3904 towards and through the indoor heat exchanger 68, into the line 3908 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The indoor heat exchanger 68 operates as the condenser of the heat pump 3902 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82.

[0181] In a space cooling and water heating mode of the system 3900, the first reversing valve 3920 is in the first position and the second reversing valve 3922 is in the second position. As such, the working fluid flows through the working fluid loop 3905 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream80. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed.

[0182] In both the space heating mode (FIG. 39) and the space cooling mode of the heat pump 3902, the water heater 3930 can be controlled to continuously or periodically cycle water through the water loop 3934 for heating the water via the WRHX 36. For example, in response to a determined need for water heating in the water heater 3930, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 3934 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 3934 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 3934, and the WRHX 36. The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 3902 in the space heating / cooling mode via the WRHX 36 when conditions in the water heater 14 allow and conditions in the heat pump 3902 demand, as described above.

[0183] The need for hot water and / or supplemental heating in the water heater 3930 can be determined as described above. For example, this can be determined by monitoring the temperature of the water exiting the tank 26 via the sensor 132, monitoring the temperature and / or the level of the water in the tank 26 via the sensor 134, or another suitable operating condition of the water heater 3930. Additionally, or alternatively, the temperature of the water exiting the WRHX 36 is monitored via the sensor 3936 to determine a need for hot water and / or supplemental heating.

[0184] FIG. 40 depicts the system 3900 in an independent space heating and water heating mode. In this mode, the first reversing valve 3920 is in the second position, isolating the WRHX 36 from the loop 3902. The second reversing valve 3922 is in the first position, directing the working fluid to flow through the working fluid loop 3905 as described above for FIG. 39, except that the working fluid flows from the discharge line 3910, through the first reversing valve 3920 and into the line 3906, bypassing the lines 3916, 3918 and the WRHX 36. The system 3900 can also be operated in an independent space cooling and water heating mode. In this mode, the first reversing valve 3920 is in the second position, isolating the WRHX 36 from the loop 3902, and the second reversing valve 3922 is in the second position, directing the working fluid to flow through the working fluid loop 3905 as described above for the space cooling and water heating mode, except that the working fluid flows from the discharge line 3910, through the first reversing valve 3920 and into the line 3906, bypassing the lines 3916, 3918 and the WRHX 36.

[0185] The system 3900 may be operated in the independent space heating and water heating mode (FIG. 40) or the independent space cooling and water heating mode when outside conditions allow (e.g., when outside conditions are suitable for the WRHX 36 to absorb heat from the outside air). The water heater 3930 can be operated to continuously or periodically water through the water loop 3934 and the isolated WRHX 36, and the WRHX 36 can operate to absorb heat from the outside environment to heat the water (e.g., from moisture in the outside air that condenses on the WRHX 36). The controller 64 can also monitor the temperature of the water exiting the WRHX 36 and, if the controller 64 determines that there is a need for water heating that is not adequately being fulfilled in the independent water heating mode, the controller 64 initiates the space heating and water heating mode of FIG. 39 (or the space cooling and water heating mode), such that the working fluid is used to heat the water. The controller 64 can also determine that the working fluid is available to heat the water as described above before initiating the space heating / cooling and water heating mode (e.g., by determining that additional heating is not needed by the heat pump 3902), to balance the ability of the heat pump 3902 to fulfill its requirements and the ability of the water heater 3930 to fulfill its requirements.

[0186] The system 3900 is operable in other operating modes than those shown in FIGS. 39 and 40 and described above. For example, the system 3900 is operable in a dedicated water heating mode, in which the first and second reversing valves 3920, 3922 are each in the first position, the indoor fan 76 is turned off, and the outdoor heat exchanger 70 operates as the evaporator. The system 3900 is also operable in a space heating only mode or a space cooling only mode, in which the heat pump 3902 conditions the inlet air stream 80 as described above while the water heater 3930 is idle (e.g., little to no water flows through the water loop 34), the first reversing valve 3920 is in the second position to isolate the WRHX 36 from the working fluid loop 3905, and the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling). The system 3900 is also operable in a defrost mode, in which the first reversing valve 3920 is in the first position, the second reversing valve 3922 is in the second position, the indoor fan 76 is turned off, the outdoor heat exchanger 70 operates as the condenser (rejecting heat to defrost the outdoor coils), and the expansion device 20 is fully opened and / or bypassed. In the defrost mode of the system 3900, when conditions in the water heater 3930 allow, the water in the water loop 3934 is used to heat the working fluid upstream from the outdoor heat exchanger 70.

[0187] Description of the controller 64 above applies to the controller 64 of the system 3900 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3900 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to control the first reversing valve 3920 and the second reversing valve 3922.

[0188] FIGS. 41 and 42 depict a fourteenth example of an integrated heat pump-water heater system 4100 that includes a heat pump 4102 operable in multiple operating modes and the water heater 3930 integrated with the heat pump 4102. The heat pump 4102 includes similar elements and components as the heat pump 3902 of FIGS. 39 and 40, with like elements and components indicated using like reference numerals. The water heater 3930 in this example includes the elements and components of the water heater 3930 as described above for FIGS. 39 and 40, including the WRHX 36 positioned outdoors. The system 4100 is operable in the operating modes described above for the system 3900.

[0189] In this example, in addition to the elements and components of the system 3900 of FIGS. 39 and 40, the system 4100 includes a third reversing valve 4108 connected between the first reversing valve 3920 and the WRHX 36, and between the indoor heat exchanger 68 and the outdoor heat exchanger 70. The third reversing valve 4108 provides additional functionality to the integrated system 4100 relative to the system 3900 of FIGS. 39 and 40. The third reversing valve 4108 is connected to the first reversing valve 3920 by a line 4106, the WRHX 36 by the line 3916, the indoor heat exchanger 68 by a line 4104, and the outdoor heat exchanger 70 by the line 3908. The expansion device 20 is positioned on the line 4104 between the indoor heat exchanger 68 and the third reversing valve 4108.

[0190] FIG. 41 depicts the system 4100 in a space heating and water heating mode, in which the first reversing valve 3920 and the second reversing valve 3922 are in the first position as described above for FIG. 39. The third reversing valve 4108 is also in a first position, which allows the working fluid to flow through a working fluid loop 4105 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 4106 towards and through the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3904 towards and through the indoor heat exchanger 68, into the line 4104 towards and successively through the expansion device 20 and the third reversing valve 4108, into the line 3908 towards and through the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The indoor heat exchanger 68 operates as the condenser of the heat pump 4102 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 4102 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82.

[0191] In a space cooling and water heating mode of the system 4100, the first reversing valve 3920 and the third reversing valve 4108 are each in the first position and the second reversing valve 3922 is in the second position. As such, the working fluid flows through the working fluid loop 4105 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 4106 towards and through the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and through the third reversing valve 4108, into the line 4104 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed.

[0192] In both the space heating mode (FIG. 41) and the space cooling mode of the heat pump 3902, the water heater 3930 can be controlled to continuously or periodically cycle water through the water loop 3934 for heating the water via the WRHX 36, as described above. The need for hot water and / or supplemental heating in the water heater 3930 can be determined as described above.

[0193] The system 4100 is operable in other operating modes including those described above for the system 3900 of FIGS. 39 and 40. For example, the system 4100 is operable in an independent space heating and water heating mode or an independent space cooling and water heating mode when outside conditions allow (e.g., when outside conditions are suitable for the WRHX 36 to absorb heat from the outside air). In the independent space heating / cooling and water heating mode of the system, the first reversing valve 3920 is in the second position (see FIG. 40), which bypasses the lines 4106, 3916, and 3918 and isolates the WRHX 36, the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling), and the third reversing valve 4108 is in the first position. The system 4100 is also operable in a dedicated water heating mode, in which the first, second, and third reversing valves 3920, 3922, 4108 are each in the first position, the indoor fan 76 is turned off, and the outdoor heat exchanger 70 operates as the evaporator. The system 4100 is also operable in a space heating only mode or a space cooling only mode, in which the heat pump 4102 conditions the inlet air stream 80 as described above while the water heater 3930 is idle (e.g., little to no water flows through the water loop 34), the first reversing valve 3920 is in the second position to isolate the WRHX 36 from the working fluid loop 3905, the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling), and the third reversing valve 4108 is in the first position. The system 4100 is also operable in a defrost mode, in which the first and third reversing valves 3920, 4108 are in the first position, the second reversing valve 3922 is in the second position, the indoor fan 76 is turned off, the outdoor heat exchanger 70 operates as the condenser (rejecting heat to defrost the outdoor coils), and the expansion device 20 is fully opened and / or bypassed. In the defrost mode of the system 4100, when conditions in the water heater 3930 allow, the water in the water loop 3934 is used to heat the working fluid upstream from the outdoor heat exchanger 70.

[0194] Description of the controller 64 above and the functions executed by the controller 64 for the operating modes of the system 3900 applies to the controller 64 of the system 4100. The controller 64 can control operation of the system 4100 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to control the first reversing valve 3920, the second reversing valve 3922, and the third reversing valve 4108.

[0195] FIG. 42 depicts the system 4100 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the third reversing valve 4108. In the thermosiphon space heating mode of the system 4100, the compressor 72 and the outdoor fan 78 are idle. The first and second reversing valves 3920, 3922 are in the first position and the third reversing valve 4108 is in a second position. The second position of the third reversing valve 4108 causes the working fluid to bypass three-way valves 3504, 3506 are operated (positioned) to bypass the outdoor heat exchanger 70 and the compressor 72, and flow between the indoor heat exchanger 68 and the WRHX 36. To enable a thermosiphon or compressor-free mode of the heat pump 4102, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 4105 using natural convection rather than by mechanical force. The system 4105 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the WRHX 36, the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0196] As shown in FIG. 42, in the thermosiphon or compressor-free mode, the reversing valves 3920, 3922, 4108 direct the working fluid through the loop 4105 as follows: working fluid flows through the line 3904 towards and through the indoor heat exchanger 68, into the line 4104 towards and successively through the expansion device 20 (which may be fully opened and / or bypassed) and the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, and back into the line 3904. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 4105 by natural convection.

[0197] The water heater 3930 is operated in the thermosiphon or compressor-free mode of FIG. 42 as described above to circulate hot water in the loop 3934 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 3934 and prevent lowering the temperature of the water in the loop 3934.

[0198] The controller 64 also determines whether to operate the system 4100 in the thermosiphon space heating mode of FIG. 42 based on the outside conditions and whether hot water is available in the water heater 3930 for heating the working fluid in the loop 4105 as described above. For example, this can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 3930 for the thermosiphon space heating mode of FIG. 42 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 4100 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 3930 for the thermosiphon space heating mode of FIG. 42 (e.g., at 1322 of FIG. 13), then the controller 64 initiates the space heating mode of the heat pump 4102 using the outdoor heat exchanger 70 as the evaporator (e.g., as shown in FIG. 41).

[0199] Table 2 below provides a summary of the operating modes (including heat pump mode and water heating mode) in which the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, 3800, 3900, and 4100 can be operated.TABLE 2Operating mode summary of example integrated heat pump-water heater systemsSpaceSpaceDefrostHeating +DedicatedCooling +modeWaterWaterWaterusingHeatingHeatingHeatingHydronicheatSpaceSpace(Groundwater(Groundwater(GroundwaterThermosiphonfromCoolingHeatingand / orand / orand / orSpacewaterSystemOnlyOnlyStandby)Standby)Standby)HeatingheaterSystemYesYesYesYesYesNoYes100(FIGS.2-4)SystemYesYesYesYesYesYesYes900(FIGS.9-12)SystemYesYesYesYesYesYesYes1400(FIGS.14 and15)SystemYesYesYesYesNoNoYes1600(FIGS.16-19)SystemYesYesYesYesNoYesYes2000(FIGS.20-22)SystemYesYesYesYesNoYesYes2300(FIG.23)SystemYesNoNoNoYesNoNo2400(FIGS.24-26)SystemYesNoNoNoYesYesNo2700(FIGS.27-30)SystemYesNoNoNoYesYesNo3100(FIG.31)SystemNoYesYesYesNoNoNo3200(FIGS.32-34)SystemNoYesYesYesNoYesNo3500(FIGS.35-37)SystemNoYesYesYesNoYesNo3800(FIG.38)SystemYesYesYesYesYesNoYes3900(FIGS.39 and40)SystemYesYesYesYesYesYesYes4100(FIGS.41 and42)

[0200] Referring to FIG. 43 and in view of the integrated heat pump-water heater systems described above, a method 4300 of operating an integrated heat pump-water heater system for an indoor space is described. The system may generally include a heat pump having a refrigerant loop (e.g., suitable piping or lines connecting indoor and outdoor sections), a compressor (which may be a scroll, reciprocating, or rotary type), an indoor air-refrigerant heat exchanger (ARHX) sometimes referred to as an indoor heat exchanger, an outdoor ARHX sometimes referred to as an outdoor heat exchanger, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In certain examples, fans or blowers are provided to force air across the indoor and / or outdoor ARHX. A network of valves, such as a reversing valve connected to the compressor discharge line and one or more additional flow-control or three-way valves, may redirect the refrigerant among the indoor ARHX, the outdoor ARHX, and the WRHX to accommodate multiple operating modes (for example, space heating, space cooling, defrost, or dedicated water heating).

[0201] Method 4300 includes circulating 4305 a refrigerant through the refrigerant loop of the heat pump. The refrigerant may be routed in conduits between the indoor ARHX and outdoor ARHX. A controller can selectively energize a blower or fan to move an air stream across one or both ARHX coils while also controlling refrigerant flow continuously or intermittently, depending on temperature demands or water-heating demands.

[0202] The refrigerant is compressed 4310 by a compressor positioned in the refrigerant loop, raising it to a relatively hot, high-pressure state suitable for releasing heat in subsequent steps. In some systems, an accumulator may be placed upstream of the compressor to manage liquid refrigerant carryover, and the compressor discharge line may feed into a reversing valve (sometimes referred to as a four-way valve).

[0203] Method 4300 provides for positioning 4315 a reversing valve on the refrigerant loop, connected to the compressor discharge or suction line, so that refrigerant flow is directed between the indoor ARHX and the outdoor ARHX based on a selected operating mode (e.g., space heating, space cooling, or defrost). In some configurations, the reversing valve feeds hot, compressed refrigerant either to the indoor coil (for heating) or to the outdoor coil (for cooling), while also returning lower-pressure vapor to the compressor's suction side.

[0204] The refrigerant passes through an indoor ARHX where heat is exchanged 43220 with an indoor air stream. During space heating, the indoor ARHX may act as a condenser, releasing heat to the indoor air. Conversely, when the system is in space cooling mode, the indoor ARHX acts as an evaporator, absorbing heat from the indoor air stream.

[0205] Heat is exchanged 4325 between the refrigerant and the outdoor air via an outdoor ARHX. In space-heating mode, this outdoor ARHX may function as an evaporator, absorbing heat from outside air. In space-cooling mode, it typically operates as a condenser rejecting heat to the outdoor environment. Depending on design, a blower or fan may drive outside air across the outdoor coil to promote efficient heat exchange.

[0206] Water is circulated 4330 in a water loop of the water heater using a water pump. For example, water may be drawn from a hot water tank outlet or, in some modes, from a cold water supply line. A series of check valves and three-way valves can be actuated to direct water through the loop in different ways (e.g., for tank heating, groundwater heating, or hydronic support).

[0207] The WRHX is used to exchange 4335 heat between the refrigerant and the water loop. Depending on system conditions, the WRHX heats water by thermally connecting to the hot, compressed refrigerant flow (for example, downstream of the compressor and before or after the indoor ARHX). Under some circumstances, the WRHX can instead deliver heat from the water to the refrigerant sometimes referred to as “hydronic heating. For example, the water may heat the refrigerant if the tank water is at a suitably high temperature and the system determines supplemental heating of the refrigerant loop.

[0208] The system positions 4340 a network of valves (for example, reversing valves or three-way valves) on the refrigerant loop to communicate with both the reversing valve and the ARHX coils. Additional solenoid valves, bypass valves, or dedicated three-way valves may selectively bypass certain coils or reroute refrigerant into the WRHX to make water heating available in different operating modes.

[0209] The network of valves is controlled to direct 4345 refrigerant flow through the WRHX so that water heating is available even during modes such as space cooling. For instance, compressed refrigerant exiting the compressor can be routed through the WRHX first, then to the outdoor ARHX (when it is acting as a condenser), thereby allowing waste heat to be captured and sent to the water loop.

[0210] At least one operating mode may isolate 4350 the compressor and the outdoor ARHX from refrigerant flow, routing refrigerant between the WRHX and the indoor ARHX only. In such embodiments, gravity-driven natural convection can circulate refrigerant without energizing the compressor, also referred to as a hydronic “thermosiphon.” This thermosiphon mode may heat the indoor air by transferring heat from relatively hot tank water to the refrigerant, then to the indoor ARHX, which can operate as a condenser coil if the fan is running.

[0211] One or more of these steps may be performed concurrently or in a different sequence. Additional sub-steps, such as cycling an outdoor fan off to preserve refrigerant temperature for water heating, may be implemented based on monitored conditions (e.g., ambient temperature, tank temperature, or user preferences). A controller typically coordinates valve positions, pump operation, and compressor usage to balance comfort and hot-water requirements.

[0212] Accordingly, the foregoing method 4300 enables integrated operation of the heat pump and water heater across multiple modes while preserving flexibility in overall layout and component selection. Additional features, examples, and variations may be implemented consistent with the broader system descriptions above, such as the inclusion of expansion devices (e.g., thermal expansion valves or fixed orifices), suction-line accumulators, and other standard vapor-compression components.

[0213] Referring to FIG. 44 and in view of the integrated heat pump-water heater systems described above, a method 4400 of operating an integrated heat pump-water heater system for an indoor space is described. The system includes a heat pump having a refrigerant loop (e.g., suitable piping or lines connecting indoor and outdoor sections), a compressor (e.g. a scroll compressor, a reciprocating compressor, or a rotary compressor), an indoor air-refrigerant heat exchanger (ARHX) to exchange heat with an indoor air stream, an outdoor ARHX to exchange heat with outdoor air, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In the example embodiment, the indoor ARHX and outdoor ARHX each include heat exchange coils and at least one fan or blower to move air across those coils. A network of valves, such as one or more reversing valves connected to the compressor's discharge or suction lines and additional three-way or flow-control valves, may reroute refrigerant among the indoor ARHX, outdoor ARHX, and WRHX to accommodate the mode of operation space heating, space cooling, defrost, or dedicated water-heating modes.

[0214] Refrigerant is circulated 4405 through the heat pump's closed-loop circuit. This controller is programmed to determine refrigerant circulation based on indoor temperature requirements or hot-water demand. As the refrigerant flows between indoor and outdoor sections, fans can be selectively energized to transfer air over the ARHX coils.

[0215] The refrigerant is compressed 4410 by a compressor connected to the refrigerant loop to raise its pressure and temperature. The compressed refrigerant is directed toward either the indoor ARHX or outdoor ARHX, depending on whether the system is operating in a space heating mode or a space cooling mode. A first reversing valve is selectively positioned 4415 on the refrigerant loop connected to the compressor so that the WRHX is either connected to, or isolated from, the refrigerant flow of the refrigerant loop. When the first reversing valve is positioned in the first position and the compressed refrigerant is directed through the WRHX to heat water in the system's water loop. When the reversing valve is positioned in the second position, the valve can bypass the WRHX, preserving higher efficiency for standard space conditioning. A second reversing valve is positioned 4420 to route refrigerant flow between the indoor and outdoor heat exchangers based on the operating mode. By controlling the configuration of the valves the system can determine which coil (indoor or outdoor) receives the compressed refrigerant and which coil handles the lower-pressure vapor returning to the compressor.

[0216] The heat from the compressed refrigerant is exchanged 4425 with the indoor air via the indoor ARHX. In the heating mode, the compressed refrigerant from the compressor is sent to the ARHX to release the heat into the indoor air stream, warming the space. Conversely, when the system is operating in the cooling mode, the indoor ARHX acts as an evaporator, absorbing heat from the indoor air. In some embodiments a fan or blower forces air across the coil for increased heat transfer. The heat from the outdoor ARHX is exchanged 4430 with the outdoor air. In the heating mode, the refrigerant may enter the outdoor coil as a low-temperature vapor, absorbing heat from outside air. In the cooling mode, the ARHX operates as a condenser, rejecting heat to the outdoor environment. The outdoor fan can be cycled on or off depending on ambient conditions, water heating demands, or efficiency considerations.

[0217] The WRHX exchanges 4435 heat with a water loop. The water loop includes a hot water tank, a pump, and various check and three-way valves for routing water from either the tank outlet or a cold supply line. Circulating water through the WRHX captures heat from the refrigerant loop in the heating mode. The WRHX may capture heat from the refrigerant loop in the cooling mode if the compressed refrigerant is sufficiently hot. The resulting heated water is then delivered back to the hot water tank or used directly. The system may run a dedicated water-heating mode by partially or fully bypassing normal space conditioning so that the WRHX becomes the primary condenser. Conversely, if tank water is sufficiently hot, the WRHX can deliver heat to the refrigerant in a “hydronic heating” scenario, for example helping defrost or supporting mild indoor heating through a thermosiphon arrangement (where gravity and temperature differentials drive natural refrigerant circulation, reducing or eliminating compressor usage).

[0218] Each of these steps 4405-4435 may be performed in series, concurrently, or in a modified order, depending on operational demands and configuration. The controller typically manages valve positions, blower or fan operation, compressor staging, and water circulation based on measured temperatures, pressures, and setpoints. The flexibility of the system provides indoor climate control and water heating simultaneously or independently, while also accommodating defrost modes or thermosiphon modes of operation. In this way, the method 4400 enables integrated operation of the heat pump and water heater across multiple modes in a cost-effective, energy-efficient manner, without sacrificing the adaptability needed for diverse climate conditions or occupant preferences.

[0219] Referring to FIG. 45, a representative flow diagram illustrates a method 4500 of operating an integrated heat pump-water heater system that provides both space conditioning and water heating. The system includes a heat pump with a refrigerant loop (for example, piping or conduits connecting indoor and outdoor sections), a compressor, an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, and a water-refrigerant heat exchanger (WRHX) thermally coupling the refrigerant loop to a water heater. A controller regulates valve positions, fan operations, and pump speeds based on ambient conditions, desired indoor temperature, or hot-water demands.

[0220] The method 4500 includes circulating 4505 refrigerant through the heat pump's refrigerant loop. The compressed, high-pressure refrigerant is directed toward a reversing valve and a network of valves, which together route the refrigerant among the indoor ARHX, the outdoor ARHX, and the WRHX.

[0221] When operating in the space heating mode 4510, the reversing valve is positioned 4515 so that hot, high-pressure refrigerant from the compressor is directed toward the indoor ARHX (which acts as a condenser) and returned from the outdoor ARHX as an evaporator. The network of valves are positioned 4520 to direct the high-pressure refrigerant from the reversing valve towards the WRHX. This may occur before or after the indoor ARHX, depending on valve arrangement. Refrigerant flowing through the WRHX transfers 4525 thermal energy to water circulating in the water loop of the water heater. A water pump draws water from a storage tank (or a cold supply line) through check valves and three-way valves, delivering it into the WRHX to absorb heat from the refrigerant. After leaving the WRHX, the refrigerant proceeds to the indoor ARHX, rejecting heat 4530 into the indoor air stream and thus warming the occupied space. The now-cooled refrigerant then travels through the outdoor ARHX, absorbing heat 4535 from outside air, and cycles back to the compressor.

[0222] When operating in the space cooling mode 4540, the reversing valve is positioned 4545 to direct the hot, high-pressure refrigerant toward the outdoor ARHX as a condenser, rejecting heat to the outside air. The refrigerant then flows into the network of valves positioned 4550 so that the refrigerant also passes through the WRHX. Heat from the refrigerant is transferred 4555 to the water circulating in the water loop and capturing unused heat. From the WRHX, the refrigerant is directed to the indoor ARHX as an evaporator. The heat from the indoor air steam is absorbed 4560 by the indoor ARHX to cool the indoor space and lower the indoor temperature. The refrigerant then returns to the ARHX to reject heat 4565 from the refrigerant to the outdoor air steam and returns to the compressor to complete the cycle.

[0223] In the space heating mode and / or the space cooling mode, the controller may enable or bypass heat transfer in the WRHX. For example, if the water tank is already at its setpoint temperature, the system may route refrigerant around the WRHX. The refrigerant loop may be directed through the WRHX to preheat water if there is a demand for hot water. By recovering thermal energy in both operating modes, the system enhances energy efficiency 4570 by utilizing the refrigerant to heat the water across the space heating mode and the space cooling mode. In the example embodiment, the water heater's pump and valves can be adjusted for tank heating, groundwater heating, or optional hydronic support (where hot tank water supplements heat for the refrigerant loop under certain conditions).

[0224] In some implementations, the system may include a dedicated defrost cycle, where the reversing valve temporarily directs hot refrigerant to the outdoor coil to melt accumulated frost. Under moderate outdoor temperatures, the controller may stage or cycle outdoor fans so the refrigerant remains sufficiently hot for water heating. The system may operate in a thermosiphon or compressor-free mode, where the compressor and outdoor ARHX are isolated, and naturally circulating refrigerant (driven by gravity and temperature differentials) transfers heat between the WRHX and the indoor ARHX to heat the indoor air using stored hot water without running the compressor.

[0225] One or more of these steps can occur at the same time or in a modified sequence. Additional sub-steps such as intermittently shutting off the outdoor fan to maintain higher refrigerant temperatures or activating a bypass line may be incorporated to optimize energy usage, meet occupant preferences, or protect system components.

[0226] FIG. 45 illustrates a method 4500 for facilitating an integrated heat pump operation for both space conditioning and water heating. The system directs refrigerant to the WRHX in either the space heating mode or the space cooling mode to repurpose unused thermal energy that would otherwise be lost, resulting in increased overall efficiency and reduced operational costs. The described systems and methods also preserves design flexibility, allowing for different compressor types (e.g., scroll, rotary, or reciprocating), various expansion devices, and optional defrost or thermosiphon capabilities.

[0227] Referring to the flow chat illustrated in FIG. 46 and in view of the integrated heat pump-water heater systems described above, a method 4600 of operating an integrated heat pump-water heater system for an indoor space is described. The system includes a heat pump with a refrigerant loop (for example, tubing or piping between indoor and outdoor sections), a compressor (such as a scroll compressor, reciprocating compressor, or rotary compressor), an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In the example embodiment, one or more fans or blowers may be provided to move air across each ARHX. A network of valves, such as a reversing valve connected to the compressor discharge line and additional three-way or flow-control valves, is arranged so that refrigerant is directed between the indoor ARHX, the outdoor ARHX, and the WRHX, depending on the operating mode (e.g., space heating, space cooling, defrost, or dedicated water heating).

[0228] The system circulates 4605 a refrigerant through the refrigerant loop of the heat pump. A controller runs the compressor to drive refrigerant flow between the indoor ARHX and the outdoor ARHX, with air being transferred across these heat exchangers by fans as needed. During the space heating mode, the refrigerant is directed by the valves to condense in the indoor ARHX, delivering heat to the indoor air. Conversely, in the space cooling mode, the refrigerant evaporates in the indoor ARHX, removing heat from the indoor air.

[0229] The refrigerant is compressed by the compressor positioned in the refrigerant loop. The compression raises the refrigerant to a relatively hot, high-pressure state, enabling subsequent heat release in the indoor coil, the outdoor coil, or the WRHX depending on the mode of operation. The system includes a suction line to manage refrigerant in the refrigerant loop. The compressor discharge line is connected to at least one reversing valve for directing compressed refrigerant to a chosen heat exchanger based on the operating mode.

[0230] A reversing valve is positioned 4610 on the refrigerant loop (for instance, in the compressor discharge or suction line) so that refrigerant flow can be toggled between the indoor ARHX and the outdoor ARHX. The reversing valve reroutes the hot, compressed refrigerant in the space heating mode or the space cooling mode, and it may also be switched to a defrost setting where compressed vapor is driven through the outdoor coil to melt frost buildup.

[0231] Water is circulated 4615 in a water loop of the water heater using a mechanical pump. In the example embodiment, the water loop includes a hot water tank, where water can be drawn from an outlet line and then returned to an inlet line after passing through the WRHX. Alternatively, water from a cold supply line may also be connected to the WRHX. Various three-way and check valves can be configured so that water is directed appropriately for heating, hydronic assist, or standby recirculation. The WRHX transfers heat between the refrigerant loop and the water loop. When the hot refrigerant flows through the WRHX, it may release a portion of its thermal energy to the circulating water, raising the water's temperature before that water returns to the storage tank or is delivered for immediate use. In some operating modes (often referred to as hydronic heating modes), hot water from the tank can be used to add heat to the refrigerant.

[0232] A network of valves (in addition to the primary reversing valve) are positioned 4620 on the refrigerant loop to allow or restrict flow into the WRHX in different operating modes. For example, additional three-way or solenoid valves may selectively bypass the WRHX if water heating is not needed or if operating conditions (like outdoor temperatures) are unfavorable. Alternatively, in space cooling mode, compressed refrigerant can be routed through the WRHX to repurpose unused thermal energy from the refrigerant for water heating.

[0233] The controller directs 4625 the refrigerant flow through the WRHX so that water heating can remain active across each of the operating modes. The circulation of the refrigerant through the configuration of valves transfers 4630 heat from the refrigerant to the water using the WRHX. For example, the refrigerant exits the compressor at high temperature, passes through the WRHX to transfer some heat into the water, and then proceeds to the outdoor ARHX to reject any remaining heat. In the example embodiment, a controller automates these steps by monitoring water temperature, indoor thermostat settings, and outdoor conditions.

[0234] In some embodiments, at least one operating mode may isolate the compressor and the outdoor ARHX entirely (e.g., turning them off or bypassing them) such that refrigerant naturally circulates between the WRHX and the indoor ARHX via gravity and a temperature / pressure differential, also referred to as “thermosiphon” mode. During the thermosiphon mode, no mechanical compression is required, and hot water in the WRHX transfers heat to the indoor ARHX when the indoor fan is running. Thermosiphon may be used to provide additional heating or to assist in defrost efforts.

[0235] Any one or more of the steps of method 4600 can be carried out in different orders, or concurrently. Various sub-steps (for example, cycling fans off to preserve refrigerant temperature for water heating, or metering refrigerant via an expansion device) may be employed based on temperature conditions and operational goals. A controller typically coordinates valve positions, compressor operation, and pump flow to balance comfort demands, water heating demands, or energy efficiency. The system can provide indoor space conditioning and heated water simultaneously or individually, depending on the mode of operation and the arrangement of the valves, heat exchangers, and control logic.

[0236] Example systems and methods described relate to integrated heat pump-water heater systems enable greater flexibility and variability to the integration of the heat pump and the water heater, enabling heating of water in the water heater in a greater number of operating modes of the heat pump, enabling heating of working fluid of the heat pump via the water heater, executing various control algorithms that enable improved and well-controlled integration of the heat pump and the water heater, expanding the ability of the heat pump and the water heater to each fulfill their respective demands for the indoor space while providing cost and energy savings via their integration, reducing the cost, complexity, and footprint associated with the integrated heat pump-water heater system, and / or enabling existing heat pump systems (e.g., in residential or commercial buildings) to be retrofitted and integrated with a water heater without costly additional infrastructure upgrades.

[0237] Technical advantages of the present disclosure include, but are not limited to including, i) enabling hot water integration without any additional refrigerant / water lines penetrating a partition or exterior wall of a building house (e.g., the heat pump can remain a 2-pipe system); ii) enabling hot water generation with heat pump system in space cooling mode, space heating mode, or dedicated hot water heating mode; iii) enabling efficient and cost-effective installation of a water heating integration kit under several scenarios, including for new homes and buildings and existing homes and buildings (e.g., in the event of water heater breaks, air conditioning and / or heat pump breaks, or for retrofitting and integrating an existing air conditioner and / or heat pump and water heater); iv) enabling the integration of an air conditioner and / or heat pump with existing hot water heater technology including, but not limited to including, electric resistance water heaters, gas or fossil fuel water heaters, electric heat pumps, dual fuel water heating, and the like, and combinations thereof; v) enables integrated water heating; vi) enabling hydronic heating (providing supplemental heating to the heat pump via hot water); vii) enabling space heating via a thermosiphon (compressor-free operation) to reduce energy utilization; and / or viii) enabling defrost of outdoor coil using hot water as a heat source (including via thermosiphon), thus reducing or eliminating the need for auxiliary refrigerant heating.

[0238] The example systems and methods described can be used in conjunction with any suitable hot water tank, including tanks that utilize an electric resistance heater and / or a gas burner as a heat source for heating water in the tank. Currently, electrification and decarbonization standards and regulations are moving from fossil fuel to electricity in order to reduce greenhouse gas emissions. The majority of single-family residential home installed base are minimum efficiency natural gas (45%) or resistance electric (35%). Future water heater efficiency standards in some states / regions may eliminate all fossil fuel water heaters and minimum efficiency resistance electric, leaving standalone heat pump water heaters as one of the only potential options for providing hot water to the indoor space. The example systems and methods address these problems and provide a reliable, cost-effective, and efficient source of heat for water that can reduce or minimize energy utilization. Additionally, the example systems and methods also enable dual fuel water heating (e.g., using both electrical resistance heating and gas heating) that can balance and minimize the energy utilization of each fuel source.

[0239] Example embodiments of the present disclosure can be implemented, for example, in HVAC systems and related methods. The systems and methods are not limited to the specific embodiments described herein, but rather, components of the system and methods may be used independently and separately from other components described herein. For example, the systems described herein may be used in systems other than HVAC systems, such as swimming pool heating systems or any other suitable system that utilizes hot water.

[0240] When introducing elements of the present disclosure or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,”“including,”“containing” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., “top”, “bottom”, “side”, etc.) is for convenience of description and does not require any particular orientation of the item described.

[0241] As various changes could be made in the above constructions and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawing(s) shall be interpreted as illustrative and not in a limiting sense.

Examples

Embodiment Construction

[0034]FIG. 1 is a schematic of a system 10 that includes a heat pump 12 and a water heating unit 14, or water heater 14. In the example system 10, the heat pump 12 operates according to a vapor-compression cycle and circulates a working fluid (e.g., a refrigerant) in a working fluid loop 15 between an indoor unit 16 and an outdoor unit 18. The indoor unit 16 is positioned in the indoor space and includes an indoor heat exchanger 68 (see, e.g., FIG. 2) that operates to condition an air stream directed to an indoor space (e.g., a building or residence), by exchanging heat between the working fluid and the air stream. The outdoor unit 18 is positioned outside the indoor space (e.g., outside the building or residence) and includes an outdoor heat exchanger 70 (see, e.g., FIG. 2) that operates to exchange heat between the working fluid and the outside air. The indoor heat exchanger 68 is also referred to as an indoor air-refrigerant heat exchanger (ARHX) and outdoor heat exchanger 70 is ...

FIELD

[0001] The field relates generally to air conditioning and hot water supply systems and methods, and more particularly, to systems and methods that enable integrating a water heating unit with a heat pump.BACKGROUND

[0002] Heat pumps are used in heating, ventilation, and air conditioning (HVAC) and refrigeration systems to control the temperature and humidity of an air stream provided to an indoor space (e.g., a building). Upper and lower temperature limits may be specified by an occupant or owner of the building, such as an employee working in the building or a homeowner. A thermostat controls operation of the heat pump based on a comparison of a measured temperature of the air stream and a target value. For example, the thermostat controls the heat pump to heat the air stream provided to the indoor space when the air temperature is less than the lower temperature limit, and the thermostat controls the heat pump to cool the air stream provided to the indoor space when the air temperature is greater than the upper temperature limit.

[0003] Known heat pumps used in HVAC and refrigeration systems include an outdoor unit having a compressor and an outdoor heat exchanger for rejecting heat into or absorbing heat from ambient air, and an indoor unit connected to the outdoor unit and including an indoor heat exchanger for absorbing heat from or rejecting heat into the air stream provided to the indoor space. A working fluid (e.g., refrigerant) is circulated in a loop between the indoor and outdoor heat exchangers (e.g., via the compressor) and undergoes phase changes that enable the heat absorption and heat rejection processes to take place in the respective heat exchangers.

[0004] Systems have been proposed that combine the working fluid loop of a heat pump with a water loop of a water heating unit. In some systems, the working fluid loop and the water loop are thermally connected by a refrigerant-water heat exchanger that enables the refrigerant to reject excess heat from the working fluid loop to provide supplemental heating of water in the water loop. The heated water can then be recirculated to a hot water tank, which also includes a primary heat source that heats the water inside the tank. The hot water inside the tank can then be supplied to various areas of the indoor space, such as a kitchen, bathroom, and the like. Providing supplemental heating from the heat pump to the water heating unit can reduce a load on the primary heat source, which provides energy and cost savings.

[0005] There are several challenges and / or constraints in combining or integrating water heating units with heat pumps. Hot water can be demanded irrespective of the current operating mode of the heat pump (e.g., whether the heat pump is in a space heating, space cooling, or idle mode). The operating mode of the heat pump changes the thermal properties of the working fluid in a given line of the working fluid loop, so the thermal connection between the water loop and the working fluid loop needs to be adjusted depending on the operating mode of the heat pump to expand the supplemental heating availability. Otherwise, supplemental heating can only be provided in a limited number of heat pump operating modes, which limits the energy and cost savings that can be realized. Combining the water heating unit and the heat pump may also require substantial reconfiguration of the heat pump to provide the thermal connection between the water and working fluid loops, which can be cost and labor intensive.

[0006] Accordingly, there is a need for systems and methods that enable integrating a water heating unit and a heat pump while providing greater variability and flexibility in the supplemental heating available to the water heating unit, reducing complexity and costs associated with the integration, and otherwise expanding the energy and cost savings that can be realized from such integration.

[0007] This background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.SUMMARY

[0008] In one aspect, an integrated heat pump-water heater system includes a heat pump, which has a refrigerant loop and both an indoor and an outdoor heat exchanger and is operable in multiple modes to condition an indoor space. A water heater is also provided, with a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects the water in the water loop and the refrigerant in the refrigerant loop. A controller, connected to both the heat pump and the water heater, is configured to operate in a space heating mode by determining when water is available to heat the refrigerant and, in response, controlling water flow to the WRHX and directing refrigerant through the WRHX. If an ambient condition is met and water is available, the controller bypasses the outdoor heat exchanger and directs refrigerant to flow between the WRHX and the indoor heat exchanger, so the water heats the refrigerant via the WRHX. If that ambient condition is not met, or if water is unavailable, the system instead directs refrigerant to flow between the indoor heat exchanger and the outdoor heat exchanger so that the refrigerant is heated by the outdoor heat exchanger.

[0009] In another aspect, an integrated heat pump-water heater system includes a heat pump, having a refrigerant loop with both an indoor heat exchanger and an outdoor heat exchanger, that is operable in multiple modes to condition an indoor space. The system also includes a water heater, which has a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects the water loop and the refrigerant loop. A controller is connected to both the heat pump and the water heater. When the system operates in a space heating mode, the controller causes the heat pump to reject heat from the refrigerant to an inlet air stream via the indoor heat exchanger; when operating in a space cooling mode, the controller causes the heat pump to absorb heat into the refrigerant from the inlet air stream via the indoor heat exchanger. In either mode, if the water heater indicates a need for water heating and the heat pump indicates that its refrigerant is available to heat the water, the controller supplies water to the WRHX and directs the refrigerant through it to heat the water. However, if in the space heating mode the refrigerant is not available to heat the water, the controller limits the water supply to the WRHX, regardless of whether the water heater requires heating.

[0010] In yet another aspect, a method of operating an integrated heat pump-water heater system for an indoor space includes circulating a refrigerant through a refrigerant loop of a heat pump operable in a space heating mode and a space cooling mode. The heat pump includes a compressor, an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, a reversing valve, a water-refrigerant heat exchanger (WRHX) thermally connecting the refrigerant loop to a water loop of a water heater, and a network of valves, all positioned on the refrigerant loop. The method further includes operating the heat pump in the space heating mode including positioning the reversing valve to direct the refrigerant from the compressor towards the network of valves and from the outdoor ARHX towards the compressor, positioning the network of valves to direct the refrigerant from the reversing valve towards the WRHX, transferring heat from the refrigerant to water in the water loop via the WRHX, directing the refrigerant from the WRHX successively through the indoor ARHX and the outdoor ARHX, rejecting heat from the refrigerant to an indoor air stream via the indoor ARHX to heat the indoor space, and absorbing heat from an outdoor air stream into the refrigerant via the outdoor ARHX. The method also includes operating the heat pump in the space cooling mode including positioning the reversing valve to direct the refrigerant from the compressor towards the outdoor ARHX and from the network of valves towards the compressor, positioning the network of valves to direct the refrigerant from the outdoor ARHX towards the WRHX, transferring heat from the refrigerant to the water in the water loop via the WRHX, directing the refrigerant from the WRHX towards the indoor ARHX, absorbing heat from the indoor air stream into the refrigerant via the indoor ARHX to cool the indoor space, and rejecting heat from the refrigerant to the outdoor air stream via the outdoor ARHX. The method further includes transferring heat from the refrigerant to the water via the WRHX in both the space heating mode and the space cooling mode to enhance energy efficiency by utilizing the refrigerant to heat the water across the space heating mode and the space cooling mode.

[0011] Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic of a system that includes a heat pump and an integrated water heating unit.

[0013] FIGS. 2-4 depict a first example of an integrated heat pump-water heater system, in various operating modes.

[0014] FIGS. 5-8 are flow diagrams of control algorithms executed by a controller of the system of FIGS. 2-4.

[0015] FIGS. 9-12 depict a second example of an integrated heat pump-water heater system, in various operating modes.

[0016] FIG. 13 is a flow diagram of a control algorithm executed by a controller of the system of FIGS. 9-12.

[0017] FIGS. 14 and 15 depict a third example of an integrated heat pump-water heater system, in various operating modes.

[0018] FIGS. 16-19 depict a fourth example of an integrated heat pump-water heater system, in various operating modes.

[0019] FIGS. 20-22 depict a fifth example of an integrated heat pump-water heater system, in various operating modes.

[0020] FIG. 23 depicts a sixth example of an integrated heat pump-water heater system, in a space heating and standby water heating mode.

[0021] FIGS. 24-26 depict a seventh example of an integrated heat pump-water heater system, in various operating modes.

[0022] FIGS. 27-30 depict an eighth example of an integrated heat pump-water heater system, in various operating modes.

[0023] FIG. 31 depicts a ninth example of an integrated heat pump-water heater system, in a space cooling and standby water heating mode.

[0024] FIGS. 32-34 depict a tenth example of an integrated heat pump-water heater system, in various operating modes.

[0025] FIGS. 35-37 depict an eleventh example of an integrated heat pump-water heater system, in various operating modes.

[0026] FIG. 38 depicts a twelfth example of an integrated heat pump-water heater system, in a space heating and standby water heating mode.

[0027] FIGS. 39 and 40 depict a thirteenth example of an integrated heat pump-water heater system, in various operating modes.

[0028] FIGS. 41 and 42 depict a fourteenth example of an integrated heat pump-water heater system, in various operating modes.

[0029] FIGS. 43A and 43B depict an example method of operating an integrated heat-pump water heater system, in various operating modes.

[0030] FIG. 44 depicts a second example method of operating an integrated water heat pump-water heater, in various operating modes.

[0031] FIG. 45 depicts a third example method of operating an integrated water heat pump-water heater, in various operating modes.

[0032] FIG. 46 depicts a fourth example method of operating an integrated water heat pump-water heater, in various operating modes.

[0033] Corresponding reference numerals indicate corresponding parts throughout the drawings.DETAILED DESCRIPTION

[0034] FIG. 1 is a schematic of a system 10 that includes a heat pump 12 and a water heating unit 14, or water heater 14. In the example system 10, the heat pump 12 operates according to a vapor-compression cycle and circulates a working fluid (e.g., a refrigerant) in a working fluid loop 15 between an indoor unit 16 and an outdoor unit 18. The indoor unit 16 is positioned in the indoor space and includes an indoor heat exchanger 68 (see, e.g., FIG. 2) that operates to condition an air stream directed to an indoor space (e.g., a building or residence), by exchanging heat between the working fluid and the air stream. The outdoor unit 18 is positioned outside the indoor space (e.g., outside the building or residence) and includes an outdoor heat exchanger 70 (see, e.g., FIG. 2) that operates to exchange heat between the working fluid and the outside air. The indoor heat exchanger 68 is also referred to as an indoor air-refrigerant heat exchanger (ARHX) and outdoor heat exchanger 70 is also referred to as an outdoor ARHX.

[0035] The heat exchangers 68, 70 each include a heat exchange coil, respectively, through which the working fluid in the loop 15 is routed. Alternatively, one or both heat exchangers 68, 70 includes a concentric tube (or shell and tube), finned tube, brazed plate, plate and frame, microchannel, or any other suitable heat exchanger design to enable the heat exchangers to function as described. In the examples described, the heat exchangers 68, 70 are equipped with or used in conjunction with one or more fans or blowers 76, 78 (see, e.g., FIG. 2). An indoor fan or blower 76 operates to force an inlet air stream 80 (see, e.g., FIG. 2) to pass across the indoor heat exchanger 68. An outdoor fan or blower 78 operates to force an outside air stream 82 (see, e.g., FIG. 2) to pass across the outside heat exchanger 70.

[0036] The outdoor unit 18 includes a compressor 72 (see, e.g., FIG. 2) that compresses the working fluid. The compressor 72 is any suitable compressor including, but not limited to, scroll, reciprocating, rotary, screw, and centrifugal compressors. The heat pump 12 also includes an expansion device 20. The expansion device 20 is an expansion valve (e.g., a thermal expansion valve). Alternatively, the expansion device 20 is any suitable expansion device, such as an orifice or capillary tube for example. The expansion device 20 is positioned between the indoor unit 16 and the outdoor unit 18. The heat pump 12 also includes a suction line accumulator 74 (see, e.g., FIG. 2) upstream from the compressor 72. The heat pump 12 is also referred to as a vapor-compression system or a refrigeration system.

[0037] In the example shown in FIG. 1, the heat pump 12 operates in a space heating mode, with the indoor heat exchanger of the indoor unit 16 operating as a condenser and the outdoor heat exchanger of the outdoor unit 18 operating as an evaporator. In the space heating mode, the working fluid is compressed using the compressor of the outdoor unit 18 and is routed towards the indoor unit 16 via a line 22 that extends through a partition 11 (e.g., a wall of the building or residence) separating the indoor space and the outside environment. The compressed working fluid rejects heat into the air stream in the indoor unit 16, condensing the working fluid and heating the air stream. The heated air stream is provided to the indoor space. The condensed working fluid exits the indoor unit 16 and flows towards the expansion device 20 via a line 24 extending through the partition 11. The expansion device 20 decompresses or expands the working fluid. The expanded working fluid flows back towards the outdoor unit 18 via the line 24. In the outdoor unit 18, the expanded working fluid absorbs heat from the outside air, evaporating the working fluid. The evaporated working fluid is again compressed using the compressor, and the process repeats.

[0038] The water heater 14 includes a hot water tank 26 that stores hot water. Hot water is supplied to the indoor space via a hot water supply line 28. The hot water tank 26 includes a heat source 30 (e.g., a gas burner and / or an electric resistance heater) that operates to heat the water inside the tank 26. In some examples, the hot water tank 26 is a dual-source tank, and includes two heat sources 30 (e.g., an electric resistance heater and a gas burner). The water heater 14 is integrated with the heat pump 12 via a water heater skid 32 of the water heater 14, also referred to as a water heating integration kit, that includes a water loop 34 and a water-refrigerant heat exchanger (WRHX) 36 positioned on the water loop 34. The water heater skid 32 enables integrating the water heater 14 with the heat pump 12 without substantial reconfiguration of the heat pump 12. For example, as shown in FIG. 1, the water heater skid 32 enables integrating the water heater 14 with the heat pump 12 without substantial re-piping of the lines 22 and 24 of the heat pump 12 and without reconfiguration of the indoor and outdoor units 16, 18. This enables integrating the water heater 14 with the heat pump 12 in a cost-effective manner while reducing the complexity of the design, maintaining a relatively small footprint of the water heater 14, and enabling easy and reliable assembly.

[0039] The water loop 34 includes a line 38 connected to an outlet 27 of the hot water tank 26 and a first three-way valve 42. The first three-way valve 42 connects the line 28, the line 38, and a line 40, and is operable (or positionable) to allow water from the line 28 to flow into the line 38 and / or the line 40. The line 40 extends between the first three-way valve 42 and a second three-way valve 44 downstream from the first three-way valve 42. The second three-way valve 44 connects the line 28, a cold water supply line 46, and a line 48 that extends between the second three-way valve 44 and the WRHX 36. The cold water supply line 46 extends from a third three-way valve 62. The second three-way valve 44 is operable (or positionable) to allow water from the line 28 and / or the cold water supply line 46 to flow into the line 48. Water in the line 48 passes through the WRHX 36 and flows into a hot water return line 50 and towards an inlet 52 of the hot water tank 26.

[0040] Check valves 54 are positioned on the lines 40, 46, and 50 and, in some examples, may additionally or alternatively be positioned on any one or more of the other lines of the water loop 34. Each check valve 54 operates to prevent backflow of water in the respective line on which the check valve is positioned.

[0041] A water pump 56 (or another mechanical fluid movement device) is positioned on the line 40 between the first and second three-way valves 42, 44. The pump 56 operates to move the water through the water loop 34. In some examples, a pump or another mechanical fluid movement device may additionally or alternatively be positioned on any one or more of the other lines of the water loop 34.

[0042] The cold water supply line 46 supplies water from a water supply 58 (e.g., a municipal or city water supply) to the water heater 14. The water supplied from the water supply 58 is used to replenish water in the hot water tank 26. Additionally, or alternatively, the water supplied from the water supply 58 can be provided directly (e.g., as cold or ambient temperature water) to the indoor space via a second supply line 60. The third three-way valve 62 is positioned at a junction of the supply lines 46, 60 and is operable (or positionable) to allow water from the water supply 58 to flow into the supply line 46 and / or the supply line 60.

[0043] The WRHX 36 is positioned on each of the water loop 34, between the lines 48 and 50, and the working fluid loop 15, on the line 22, and thermally connects water in the water loop 34 with the working fluid in the working fluid loop 15. The WRHX 36 operates to exchange heat between the water loop 34 and the working fluid loop 15 and, in particular, to heat the water in the loop 34. In the example of FIG. 1, heat from the working fluid in the line 22 is rejected into the water in the WRHX 36 while the heat pump 12 is operating in the space heating mode. Heating the water in the water loop 34 using the WRHX 36 can reduce the load on the heat source 30, thereby reducing costs and energy usage associated with the water heater 14.

[0044] The system 10 also includes a controller 64 communicatively connected to various components of the system 10, including the heat pump 12 and the water heater 14, and other components of the system 10 such as sensors that monitor operating conditions of the system 10. Although a single controller 64 is shown and described, the controller 64 in some examples includes multiple controllers 64. The multiple controllers 64 may be centralized or decentralized. The controller 64 controls various aspects and parameters of the system 10 during operation.

[0045] The controller 64 receives feedback and monitored process information from one or more sensors of the system 10 for continuous, periodic, or intermittent monitoring of conditions within the system 10 (e.g., temperature and / or pressure of the working fluid in the loop 15, temperature and / or pressure of the water in the loop 34, ambient temperature and / or humidity, a level and / or temperature of the water stored in the tank 26, etc.), among other information. In some examples, the controller 64 additionally or alternatively receives information (e.g., an operating mode request) from a thermostat associated with the heat pump 12. Alternatively, the thermostat may be included as a component of the controller 64. The controller 64 includes a communication interface to communicatively couple the controller 64, via one or more connections 66, to one or more components of the system 10. The one or more connections 66 communicatively couple the controller 64 to the heat pump 12, the water heater 14, and / or other components (e.g., sensors) of the system 10. The communication interface includes, for example, a wired or wireless network adapter and / or a wireless data transceiver for use with a mobile telecommunications network. In this way, the one or more connections 66 communicatively couple the controller 64 to the one or more components of the system 10 via a wired and / or wireless connection.

[0046] The controller 64 is a computer system that includes at least one processor and at least one memory device. The memory device includes a non-transitory computer-readable medium and program that are accessed by the processor and executable to perform the functions described for the controller 64. The controller 64 receives inputs (e.g., monitored conditions of the system 10). For example, the inputs include monitored temperature and pressure information from one or more stages of the heat pump 12 and / or water heater 14, and / or ambient temperature and / or humidity. The controller 64 is operable to process the inputs using one or more control algorithms and generate an output for controlling operation of the system 10, and more particularly, operation of the heat pump 12 and the water heater 14. The controller 64 continuously, periodically, or intermittently generates outputs based on the processed inputs.

[0047] In one example operation, the controller 64 determines a suitable operating mode of the heat pump 12 and generates an output to control the heat pump 12 to operate in the determined operating mode. The operating mode is determined, for example, based on a comparison between a measured temperature of ambient air and a temperature setpoint (e.g., a user specified or pre-determined setpoint). In the illustrated example, the controller 64 controls the heat pump 12 to operate in a space heating mode, described above. The controller 64 also determines a need for heating the water in the water heater 14 (i.e., to provide additional hot water and / or supplemental heating to the water heater 14). The need for water heating is determined, for example, based on a temperature of water in the loop 34 and / or the tank 26, a level of the water in the tank 26, a pre-determined time duration since the last water heating cycle, and / or a user input request. In response to a determined need for water heating, the controller 64 generates an output to control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. The controller 64 also generates output to position the three-way valves 42, 44 to allow the water to flow through the loop 34. Heating the water by operating the pump 56 and the three-way valves 42, 44 to circulate water through the loop 34 is referred to as tank or standby water heating. Additionally, or alternatively, the controller 64 generates an output to control the three-way valves 62, 44 to allow water to flow through the cold water supply line 46, the water loop 34, and the WRHX 36. Heating the water flowing through the loop via the cold water supply line 46 is referred to as groundwater heating. In some examples, the controller 64 may allow the water to continuously or periodically flow through the loop 34 and the WRHX 36 via the cold water supply line 46 and / or the line 38 to enable standby water heating of water in the water heater 14.

[0048] In the example of FIG. 1, the controller 64 may determine whether the need for water heating can be met by circulating water through the loop 34 and the WRHX 36. For example, the controller 64 determines whether the operating mode of the heat pump 12 enables heating water in the loop 34 via the WRHX 36. As shown in FIG. 1, supplemental heating of the water in the loop 34 is available when the heat pump 12 is operating in the space heating mode, since the working fluid in the line 22 is at a suitable stage in the heat pump cycle, specifically, in a compressed, relatively hot vapor stage, for transferring heat to the water in the loop 34. In this example, the controller 64 may determine that water heating is available via the WRHX 36 since the heat pump 12 is operating in the space heating mode, and, in response to a determined need for water heating, the controller 64 generates an output to control the water heater 14 to circulate water through the water loop 34 and the WRHX 36 as described above.

[0049] Other operating modes of the heat pump 12 may not be suitable for providing supplemental heating to the water loop 34. For example, in a space cooling mode, the heat pump is operated in reverse and flow of working fluid (e.g., refrigerant) through the lines is reversed (with the indoor heat exchanger operating as the evaporator and the outdoor heat exchanger operating as the condenser). As such, the working fluid in the line 22 is exiting the evaporator and is at low pressure. At this low pressure stage, prior to compression, the working fluid may not reject heat as effectively as compressed refrigerant. In an idle mode of the heat pump 12, no working fluid may flow through the line and is not available for supplemental heating via the WRHX 36. In these examples, the controller 64 may determine that water heating is not available via the WRHX 36 when the heat pump 12 is in a space cooling mode or an idle mode, and overrides any response to a determined need for water heating.

[0050] The examples described below include additional elements and components, relative to the system 10 of FIG. 1, that provide greater flexibility and variability to the integration of the heat pump 12 and the water heater 14 and enable heating of water in the water heater 14 in a greater number of operating modes of the heat pump 12. Additionally, in some examples, heating of working fluid of the heat pump 12 via the water heater 14 is enabled. The controller 64 is also equipped to execute various control algorithms, described below, that enable improved and well-controlled integration of the heat pump 12 and the water heater 14, and expand the ability of the heat pump 12 and the water heater 14 to each fulfill their respective demands for the indoor space while providing cost and energy savings via their integration.

[0051] Accordingly, the examples described below relate to integrated heat pump-water heater systems that include a heat pump including a working fluid loop and operable in multiple operating modes for an indoor space, a water heater including a water loop, and a water-refrigerant heat exchanger (WRHX) that thermally connects the water loop and the working fluid loop, where heat transfer occurs between the water loop and the working fluid loop in the multiple operating modes. In various examples, depending on the operating mode of the heat pump and a determined need for water heating in the water heater, a controller controls a path that the working fluid travels in the working fluid loop (e.g., by controlling positions of each of a network of valves) in order to enable simultaneously operating the heat pump in its designated mode and transferring heat between the water heater and the heat pump.

[0052] In the examples described below, the systems include elements and components that are included in the system 10 of FIG. 1, which are indicated using like reference numerals. Description of the elements and components above applies similarly to the elements and components included in the systems described below and indicated using like reference numerals unless expressly stated otherwise or the context clearly indicates otherwise.

[0053] The elements and components of the systems described below can be combined in any suitable combination. Any feature or element described with reference to one of the systems that is not described with reference to another one of the systems is not to be interpreted as limiting in any sense, and such element and feature can be included in such other system unless expressly stated otherwise or the context clearly indicates otherwise.

[0054] FIGS. 2-4 depict a first example of an integrated heat pump-water heater system 100 that includes a heat pump 102 operable in multiple operating modes and the water heater 14 integrated with the heat pump 102. The heat pump 102 includes similar elements and components as the heat pump 12 of FIG. 1, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIG. 1.

[0055] In this example, the system 100 includes a first reversing valve 106 and a network of valves 107 on a working fluid loop 105 of the heat pump 102 to control flow of a working fluid (e.g., refrigerant) through the loop 105. The first reversing valve 106 is operable (or positionable) to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 105 based on an operating mode (e.g., space heating or space cooling) of the heat pump 102. The network of valves 107 is connected to the first reversing valve 106. The network of valves 107 in this example includes a second reversing valve 108 and a third reversing valve 110. The valves 108, 110 of the network of valves 107 are independently operable to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 102. In particular, the valves 108, 110 are operable to direct the flow of the working fluid such that the working fluid flows through the WRHX 36 at a suitable stage in the heat pump cycle (e.g., in a compressed, relatively hot vapor stage) for transferring heat to the water in the loop 34 at different operating modes of the heat pump 102. In a space heating mode of the heat pump 102 (FIG. 2), the indoor heat exchanger 68 operates as the condenser (rejecting heat into the inlet air stream 80) and the outdoor heat exchanger 70 operates as the evaporator (absorbing heat from the outside air stream 82). In a space cooling mode of the heat pump 102 (FIG. 3), the indoor heat exchanger 68 operates as the evaporator (absorbing heat from the inlet air stream 80) and the outdoor heat exchanger 70 operates as the condenser (rejecting heat into the outside air stream 82).

[0056] The first reversing valve 106 is connected to the compressor 72 by a discharge line 112 downstream from the compressor 72 and by a suction line 118 upstream from the compressor 72. The first reversing valve 106 is also connected to the outdoor heat exchanger 70 by a line 114 and the second reversing valve 108 by a line 116. The second reversing valve 108 is connected to the third reversing valve by a line 122 and by a line 124. The WRHX 36 is positioned on the line 122 between the second reversing valve 108 and the third reversing valve 110. The second reversing valve 108 is also connected to the outdoor heat exchanger 70 by a line 120. The third reversing valve 110 is also connected to the indoor heat exchanger 68 by a line 126 and by a line 128. The expansion device 20 is positioned on the line 126 between the indoor heat exchanger 68 and the third reversing valve 110.

[0057] Referring to FIG. 2, in a space heating mode of the heat pump 102, the first reversing valve 106 is in a first position in which working fluid exiting the compressor 72 via the discharge line 112 is directed by the first reversing valve 106 towards the network of valves 107 and, specifically, the second reversing valve 108 via the line 116. The working fluid is then directed by the network of valves 107 to flow through the WRHX 36 as compressed, relatively hot fluid downstream from the compressor 72 for transferring heat to the water in the loop 34, and then through the indoor heat exchanger 68, the expansion device 20, and through the second reversing valve 108. In particular, each of the second and third reversing valves 108, 110 are in a first position such that the working fluid from the lines 112 and 116 flows through the second reversing valve 108 into the line 122 and through the WRHX 36, and then through the third reversing valve 110 into the line 128. The working fluid 128 then flows from the line 128, through the indoor heat exchanger 68, into the line 126 and through the expansion device 20. The working fluid 126 is directed from the line 126 by the third reversing valve 110 into the line 124 and back through the second reversing valve 108. The second reversing valve 108 then directs the working fluid towards the outdoor heat exchanger 70 via the line 120. The working fluid exits the outdoor heat exchanger 70 via the line 114 and is directed by the first reversing valve 106 in the first position into the suction line 118 and back towards the compressor 72.

[0058] Referring to FIG. 3, in a space cooling mode of the heat pump 102, the first reversing valve 106 and the network of valves 107 are each in a second position, reversed relative to the respective first position, to reverse the flow direction of the working fluid in the loop 105 while still enabling the working fluid to flow through the WRHX 36 as compressed, relatively hot fluid downstream from the compressor 72 for transferring heat to the water in the loop 34. The first reversing valve 106 in the second position directs the working fluid exiting the compressor 72 via the discharge line 112 towards the outdoor heat exchanger 70. The working fluid exits the outdoor heat exchanger 70 and flows through the line 120 towards the second reversing valve 108 which, in the second position, directs the working fluid from the line 120 into the line 122 and through the WRHX 36. In relatively hot outside temperature conditions, a relatively small amount of heat is transferred between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70, such that the working fluid in the lines 120, 122 has the capability of rejecting heat into the water loop 34 via the WRHX 36. Alternatively, in some examples, such as in mild outside temperature conditions where a relatively greater amount of heat transfer can take place using the fan 78. The outdoor fan 78 can be cycled, idle and / or bypassed to maintain heat in the working fluid for rejecting into the water loop 34 via the WRHX 36. Operation and / or bypass of the outdoor fan 78 in the space cooling mode can be controlled by monitoring the ambient conditions and / or conditions of the working fluid in the line 120 via a sensor 130 (e.g., temperature sensor) to control the heat rejection capability of the working fluid flowing through the WRHX 36 in the space cooling mode of the heat pump 102.

[0059] Still referring to FIG. 3, the working fluid flows from the WRHX 36 through the line 122 towards the third reversing valve 110. In the second position, the third reversing valve directs the working fluid into the line 126 and through the expansion device 20. The working fluid then flows through the indoor heat exchanger 68, into the line 128 and back through the third reversing valve 110 which then directs the working fluid into the line 124 and towards the second reversing valve 108. The second reversing valve 108 in the second position directs the working fluid from the line 124 towards the first reversing valve 106 via the line 116. The first reversing valve 106 in the second position directs the working fluid from the line 116 into the suction line 118 and back towards the compressor 72.

[0060] In both the space heating mode (FIG. 2) and the space cooling mode (FIG. 3) of the heat pump 102, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0061] Referring to FIG. 4, the system 100 is also operable in a dedicated water heating mode. In the illustrated example, the system 100 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58. Additionally, or alternatively, the system 100 can be operated in the dedicated water heating mode to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the first reversing valve 106 and the network of valves 107 are each positioned in the first position and direct flow of the working fluid through the working fluid loop 105 as described above for the space heating mode with reference to FIG. 2. The outdoor heat exchanger 70 is operated as the evaporator, as described above for the space heating mode with reference to FIG. 2. The indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 102. The water heater 14 is operated as described above to flow water through the water loop 34 for heating via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0062] In some examples, the system 100 is also operable in a space heating only mode or a space cooling only mode. In these operating modes, the heat pump 102 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34).

[0063] The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 102 in the space heating and / or space cooling mode. The controller 64 may determine that the water heater 14 is available for hydronic heating when the controller 64 determines that there is hot water available in the water heater 14 for heating the working fluid (e.g., based on a temperature of the water in the loop 34, a level and / or temperature of the water stored in the tank 26, or another operating condition of the water heater 14). The controller 64 may also determine a need for supplemental heating of the working fluid in the heat pump 102 using the WRHX 36 (e.g., based on a temperature of the working fluid in the loop 15, ambient temperature and / or humidity, or another operating condition of the heat pump 102). In response, the controller 64 can initiate a hydronic heating mode by controlling the water heater 14 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0064] FIGS. 5-8 depict example flow diagrams of control algorithms according to which the controller 64 controls operation of the system 100 of FIGS. 2-4. Description of the controller 64 with reference to FIG. 1 applies to the controller 64 of the system 100 unless expressly stated otherwise or the context clearly indicates otherwise. As described above with reference to FIG. 1, the controller 64 receives inputs (e.g., monitored conditions of the system 100), processes the inputs using control algorithms (e.g., those described below for FIGS. 5-8), generates output for controlling operation of the heat pump 102 and the water heater 14. In the system 100, the inputs include measured parameters received from sensors 130, 132, 134, 136, 138 (e.g., temperature sensors) associated with the heat pump 102 and the water heater 14. In the illustrated example, the sensors include a temperature sensor 130 positioned on the line 120 between the second reversing valve 108 and the outdoor heat exchanger 70, a temperature sensor 132 positioned on the line 38 of the water loop 34 downstream from the outlet 27 of the tank 26, a level sensor 134 connected to the tank 26, an ambient temperature sensor 136, and a temperature sensor 138 for the inlet air stream 80. Any suitable number of sensors (e.g., temperature, pressure, or other sensors) can be used and located at any suitable position in the heat pump 102 (e.g., on the working fluid loop 105) and / or in the water heater 14 (e.g., on the water loop 34) to enable the controller to function as described.

[0065] Referring to FIG. 5, which shows a flow diagram 500 of a main control algorithm for the system 100, the controller 64 monitors 502 a temperature of the water in the water loop 34 in the line 38 proximate the outlet 27 of the tank 26 (i.e., the water exiting the tank 26) via the sensor 132. Additionally, or alternatively, the controller 64 monitors 502 a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14. The controller 64 may also log the monitored 502 temperature over a predetermined time period (e.g., 48 hours). Based on the monitored 502 temperature, the controller 64 determines 504 whether the temperature of the water exiting the tank 26 is rising or falling. An increase in the monitored 502 temperature is indicative that there is not an immediate need for water heating in the water heater 14, and the controller 64 then determines 506 a requested operating mode of the heat pump 102 for further instruction on how to control the system 100, described below. A decrease in the monitored 502 temperature is indicative that there is a need for water heating in the water heater 14.

[0066] In response to determining 504 that the monitored 502 temperature is decreasing, the controller 64 determines 508 whether a pre-determined time period (e.g., 15 minutes) has elapsed since the last call for water heating (or since the last water heating cycle). For example, the controller 64 determines 508 whether the pre-determined time period has elapsed since the last instance of the water pump 56 being operated to circulate water through the water loop 34. When it is determined 508 that the pre-determined time period has not elapsed, the controller 64 reverts back to monitoring 502 the temperature of the water exiting the tank 26 (or another suitable operating condition of the water heater 14), or another suitable operation to enable the controller 64 to function as described.

[0067] When it is determined 508 that the pre-determined time period has elapsed, the controller 64 initiates a water heating operation at 510 to transfer heat between the working fluid loop 105 and the water loop 34 to provide water heating. For example, the controller 64 controls 510 (e.g., turns on) the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, and positions the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 controls 510 the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. Concurrently, depending on the operating mode of the heat pump 102, the controller 64 controls the network of valves 107 to direct the working fluid through the WRHX 36 at a suitable stage in the heat pump cycle for transferring heat with the water in the water loop 34.

[0068] During the water heating operation initiated at 510, the controller 64 continues to monitor 502 the temperature of the water exiting the tank 26. Additionally, or alternatively, the controller 64 monitors 502 a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14. The controller 64 determines 512 whether to continue or cease the water heating operation at 512 based on whether the monitored 502 temperature (or condition) meets a predefined or predetermined criterion. For example, the controller 64 determines 512 whether to continue or cease the water heating operation at 512 based on whether the temperature of the water exiting the tank 26 meets a predefined temperature value or is within a predefined temperature range (e.g., whether the temperature of the water is within 5° F. of a maximum water temperature logged over the pre-determined time period at 502). If the monitored 502 temperature (or condition) meets the predefined criterion, the water heating operation is ceased at 514 (e.g., by turning of the water pump 56 and / or limiting flow of water through the water loop 34) and the controller 64 reverts back to monitoring 502 the temperature of the water exiting the tank 26 (or another suitable operating condition of the water heater 14), or another suitable operation to enable the controller 64 to function as described.

[0069] If the monitored 502 temperature (or condition) does not meet the predefined criterion, the controller 64 may continue the water heating operation initiated at 510 and continue to monitor 502 the temperature (or condition) against the predefined criterion. At this stage, the controller 64 also determines 506 a requested operating mode of the heat pump 102 for further instruction on how to control the system 100. The controller 64 may receive the requested operating mode information directly from a user input and / or from a thermostat associated with the heat pump 102.

[0070] FIG. 6 is an example flow diagram 600 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is operating in a space heating mode (as shown in FIG. 2). During the space heating mode, the outdoor heat exchanger 70 operates as the evaporator and absorbs heat from the outside air stream 82. In cold outside air conditions, this creates the risk of frost building up on the outdoor coils of the outdoor heat exchanger 70. The heat pump 102 is periodically operated in a defrost mode, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove the frost. When the heat pump 102 is operating in the space heating mode, the controller 64 determines 602 whether there is a demand for a defrost mode operation. A demand for the defrost mode may occur, for example, when a pre-determined period of time has elapsed since the last defrost mode operation. Additionally, or alternatively, a demand for the defrost mode operation may occur when a difference between defined temperature setpoint (e.g., a user defined temperature setpoint at the thermostat) and the outside air temperature is equal to or greater than a predetermined value, e.g., greater than or equal to 15° F.

[0071] When a demand for the defrost mode operation occurs, the controller 64 initiates the defrost mode operation, or defrost cycle, at 606. This includes positioning 608 the first reversing valve 106 in the second position and each the network of valves 107 of the heat pump 102 in the first position to direct the working fluid in a defrost mode flow direction (see FIG. 11, described below), and operating 610 the outdoor heat exchanger 70 as a condenser such that compressed, hot working fluid flows through the outdoor coils for the defrost operation. The outdoor fan 78 may be idle (e.g., turned off) to enhance the defrost operation on the outdoor coils. The indoor heat exchanger 68 is controlled 612 to be idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space during the defrost cycle. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode.

[0072] During the defrost cycle initiated at 606, the controller 64 also determines 614 whether to operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. As described above, when the controller 64 implements the control algorithm of FIG. 6, there may not be an immediate need for water heating in the water heater 14 as determined at 504. This may signal that there is hot water available in the water heater 14 to provide heating to the working fluid in the loop 105 via the WRHX 36. Accordingly, during the defrost cycle, the controller 64 may operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, such that the hot water heats the working fluid in the line 122 before the working fluid is directed back towards the compressor 72. Alternatively, in some examples, the controller 64 may determine that there is not hot water available in the water heater 14 to heat the working fluid in the loop 105 when the heat pump 102 is in the defrost cycle. For example, referring to FIG. 5, when the monitored 502 temperature (or condition) does not meet the predefined criterion, this may signal that there is not hot water available for heating the working fluid. In these situations, the controller 64 does not operate the water pump 56, such that a suitable level of hot water in the tank 26 is maintained to fulfill hot water demands in the indoor space. In this way, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 102 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. If, when there is no hot water available for heating the working fluid and the water pump 56 is turned off, the demand for the defrost cycle is still active, the controller 64 may operate (e.g., turn on) the indoor fan 76 such that heat can be absorbed into the working fluid at the indoor heat exchanger 68.

[0073] When the controller 64 determines (at 616) that the demand for the defrost cycle of the heat pump 102 terminates (e.g., after a pre-determined defrost duration), or when the controller 602 determines that there is not a demand for a defrost cycle at 602, the controller 64 initiates (or continues) the space heating mode of the heat pump 102 at 618. In the space heating mode, as shown in FIG. 2, the controller 64 positions 620 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the first position, operates 622 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and operates 624 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils. At 626, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 600 at 628 described below. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0074] At 628, the controller 64 determines whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). When the controller 64 determines 628 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. This controls (maintains) the ability of the heat pump 102 to provide the additional heating of the inlet air stream 80. In response, the controller 64 does not operate the water heater 14 to flow water through the water loop 34 and WRHX 36, irrespective of any demand for heating of water in the water heater 14. In this way, as described above, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 102 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. The controller 64 then reverts to operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0075] When the controller 64 determines 628 that there is not a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 meets the setpoint temperature), then the controller determines that there is availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. At 630, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 630 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 630 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 102 in the space heating mode and, at 632, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 630, or to any one of operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0076] When the controller 64 determines 630 that there is a need for water heating in the water heater 14, at 634 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 634 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. During the water heating operation initiated at 634, the controller 64 also continues to monitor at 636 whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). If there is not a demand for additional heating of the inlet air stream 80, the water heating operation initiated at 634 may continue until there is no longer a need for water heating in the water heater 14. When the controller 64 determines 636 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. In response, the controller 64 controls the water heater 14 to stop flowing water through the water loop 34 and WRHX 36 (e.g., by turning off the pump 56), irrespective of the demand for heating of water in the water heater 14 determined at 634. The controller 64 may then revert to operation 630, or to any one of operation 506 of FIG. 5, operation 602 of FIG. 6, or operation 626 of FIG. 6 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0077] FIG. 7 is an example flow diagram 700 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is operating in a space cooling mode (as shown in FIG. 3). The controller 64 initiates (or continues) the space cooling mode of the heat pump 102 at 702. In the space cooling mode, as shown in FIG. 3, the controller 64 positions 704 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the second position, operates 706 the outdoor heat exchanger 70 as the condenser of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils, and operates 708 the indoor heat exchanger 68 as the evaporator of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils. At 710, the controller 64 determines whether the demand for the space cooling mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 700 at 712 described below. If the demand for the space cooling mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0078] At 712, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 712 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 712 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 102 in the space cooling mode and, at 722, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 702, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0079] When the controller 64 determines 712 that there is a need for water heating in the water heater 14, at 714 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 634 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0080] As described above, in the space cooling mode, the ability of the working fluid to transfer heat into the water in the loop 34 varies based on the outside temperature conditions, which affect the amount of heat transfer that occurs between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70. Smaller heat transfer in the outdoor heat exchanger 70, which is more likely to occur in hot temperature outside conditions, provides more capability of the working fluid in the line 122 to reject heat into the water loop 34 via the WRHX 36. The controller 64 monitors at 716 the ability of the working fluid exiting the outdoor heat exchanger 70 to transfer heat into the water in the loop 34 via the WRHX 36 during the water heating operation initiated at 714. In this example, the controller 64 monitors 716 the temperature of the working fluid exiting the outdoor heat exchanger 70 in the line 120 via the sensor 130. Additionally, or alternatively, the controller 64 may monitor 716 any suitable operating condition of the heat pump 102 indicative of the ability of the working fluid to transfer heat via the WRHX while the heat pump 102 is in the space cooling mode. For example, the controller 64 monitors 716 the ambient temperature via the sensor 136 and / or a temperature of the working fluid in the 122 upstream from the WRHX 36. At 718, the controller 64 determines whether the monitored 716 condition satisfies a predetermined criterion that is indicative of effective heat transfer between the working fluid in the line 122 and the water in the loop 34 via the WRHX 36. For example, the controller 64 determines whether the monitored 716 temperature of the working fluid in the line 120 exiting the outdoor heat exchanger 70 meets or exceeds a threshold or predetermined temperature value (e.g., 130° F.) that is indicative of effective heat transfer. If the monitored 716 condition (e.g., temperature) meets or exceeds the predetermined criterion (e.g., the predetermined value), the controller 64 takes no further action and allows operation to continue. If the monitored 716 condition (e.g., temperature) is below the predetermined criterion (e.g., the predetermined temperature value), the controller 64 may cycle, bypass, and / or operate as idle the outdoor fan 78 at 720. The controller 64 may then revert to operation 702, operation 712, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0081] FIG. 8 is an example flow diagram 800 of a control algorithm according to which the controller 64 controls the system 100 when the heat pump 102 is not operating in a space cooling mode or a space heating mode (i.e., when there is no request for conditioning the inlet air stream 80 via the heat pump 102). When the heat pump 102 is not being used to condition the inlet air stream 80, the controller determines at 802 whether or not there is a need for water heating in the water heater 14. This can be determined at 802 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 802 that there is not a need for water heating in the water heater 14, the controller 64 maintains the heat pump 102 in the idle mode, or turns the heat pump 102 off, at 804. This includes de-energizing the first reversing valve 106 and the network of valves 107 at 808 and fans 76, 78 of the indoor and outdoor heat exchangers 68, 70 at 810. The controller 64 also controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 may then revert to operation 802, or to operation 506 of FIG. 5 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0082] When the controller 64 determines 802 that there is a need for water heating in the water heater 14, the controller 64 initiates the dedicated water heating mode of the system 100 (see FIG. 4) at 812. As described with reference to FIG. 4, in the dedicated water heating mode, the controller 64 positions 814 each of the first reversing valve 106 and the network of valves 107 of the heat pump 102 in the first position, and operates 816 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. At 818, the controller 64 also controls the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positions the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 818 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. At 820, the controller 64 determines whether the demand for the dedicated water heating mode is still active. If so, the controller 64 continues through the operations 814-818. If the demand for the dedicated water heating mode has terminated (e.g., based on the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14), then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 102 for further instruction on how to control the system 100, or another suitable operation to enable the controller 64 to function as described.

[0083] FIGS. 9-12 depict a second example of an integrated heat pump-water heater system 900 that includes a heat pump 902 operable in multiple operating modes and the water heater 14 integrated with the heat pump 902. The heat pump 902 includes elements and components that are included in the heat pump 12 of FIG. 1 and the heat pump 102 of FIGS. 2-4, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4.

[0084] In this example, the system 900 includes the first reversing valve 106 and a network of valves 907 on a working fluid loop 905 of the heat pump 902 to control flow of a working fluid (e.g., refrigerant) through the loop 905. The first reversing valve 106 is operable (or positionable) as described above to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 905 based on an operating mode (e.g., space heating or space cooling) of the heat pump 902. The network of valves 907 is connected to the first reversing valve 106 and includes the second reversing valve 108 and the third reversing valve 110. The second and third reversing valves 108, 110 of the network of valves 907 are independently operable (or positionable) to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 902, as described above for the network of valves in FIGS. 2-4. The system 900 is operable in the operating modes (e.g., the space heating mode of FIG. 2, the space cooling mode of FIG. 3, and the dedicated water heating mode of FIG. 4) described above for the system 100 and includes the functionality and advantages of the system 100.

[0085] Additionally, in this example, the network of valves 907 includes a first three-way valve 904 positioned between the line 122 and the second reversing valve 108 and a second three-way valve 906 positioned between the third reversing valve 110 and the line 126. The three-way valves 904, 906 are connected by a bypass line 908, and are operable (or positionable) to direct fluid through the bypass line 908 to provide greater variability and flexibility in operating the system 900. For example, the three-way valves 904, 906 and the bypass line 908 enable expanding the operating modes in which the system 900 can be operated while heat is transferred between the loop 905 and the water loop 34 via the WRHX 36, as will be described below.

[0086] Referring to FIG. 9, in a space cooling mode of the heat pump 902, the reversing valves 106, 108, and 110 are each in the second position, similar to the space cooling mode of the heat pump 102 shown in FIG. 3. As described above, the reversing valves 106, 108, 110 in their respective second position direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 114 towards and through the outdoor heat exchanger 70, into the line 120 towards and through the second reversing valve 108, into the line 122 towards and successively through the WRHX 36 and the third reversing valve 110, into the line 126 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 128 towards and back through the third reversing valve 110, into the line 124 towards and back through the second reversing valve 108, into the line 116 towards and back through the first reversing valve 106, and into the suction line 118 towards the compressor 72. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed to maintain heat in the working fluid for rejecting into the water loop 34 via the WRHX 36. In the space cooling mode of FIG. 9, each of the first three-way valve 904 and the second three-way valve 906 are in a first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0087] Referring to FIG. 10, in a space heating mode of the heat pump 902, the reversing valves 106, 108, and 110 are each in the first position, similar to the space heating mode of the heat pump 102 shown in FIG. 3. As described above, the reversing valves 106, 108, 110 in their respective first position direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 116 towards and through the second reversing valve 108, into the line 122 towards and successively through the WRHX 36 and the third reversing valve 110, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and successively through the expansion device 20 and the third reversing valve 110, into the line 124 towards and back through the second reversing valve 108, into the line 120 towards and through the outdoor heat exchanger 70, into the line 114 towards and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the space heating mode of FIG. 10, each of the first three-way valve 904 and the second three-way valve 906 are in the first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0088] In both the space heating mode (FIG. 10) and the space cooling mode (FIG. 9) of the heat pump 902, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0089] FIG. 11 depicts the system 900 in a defrost mode, described above with reference to FIG. 6. The system 100 of FIGS. 2-4 is also operable in the defrost mode shown in FIG. 11. As described above, during space heating, the heat pump 902 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, the first reversing valve 106 is in the second position, and the second and third reversing valves 108, 110 are in the first position. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The reversing valves 106, 108, 110 are positioned to direct the working fluid through the loop 905 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 114 towards and through the outdoor heat exchanger 70, into the line 120 towards and through the second reversing valve 108, into the line 124 towards and through the third reversing valve 110, into the line 126 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 128 towards and through the third reversing valve 110, into the line 122 towards and successively through the WRHX 36 and the second reversing valve 110, into the line 116 towards and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the defrost mode of FIG. 11, each of the first three-way valve 904 and the second three-way valve 906 are in the first (non-bypass) position, such that the working fluid is not redirected from either line 122 or line 126 into the bypass line 908.

[0090] In the defrost mode of FIG. 11, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 902 is in the defrost mode as described above with reference to FIG. 6. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIG. 6, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0091] FIG. 12 depicts the system 900 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 904, 906 and the bypass line 908. In this space heating mode, the outdoor components of the heat pump 902, including the compressor 72 and the outdoor fan 78, are idle. The network of valves 907 is operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 902 as described below. To enable a thermosiphon or compressor-free mode of the heat pump 902, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 905 using natural convection rather than by mechanical force. The system 900 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0092] In the thermosiphon or compressor-free mode of FIG. 12, each of the three-way valves 904, 906 is in a second (bypass) position to allow the working fluid to flow through the bypass line 908 between the lines 122 and 126. The three-way valves 904, 906 in the second position restrict flow of the working fluid into the lines 116, 120, and 124, which isolates the second reversing valve 108, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70 from flow of the working fluid. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The third reversing valve 110 is in the first position to direct fluid flowing through the line 122 into the line 128 towards the indoor heat exchanger 68. As shown in FIG. 12, in the thermosiphon or compressor-free mode, the third reversing valve 110 in the first position and the first and second three-way valves 904, 906 in the second position direct the working fluid through the loop 905 as follows: working fluid flows through the line 122 and the WRHX 36, towards and through the third reversing valve 110, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and successively through the expansion device 20 and the second three-way valve 906, into the line 908 towards and through the first three-way valve 904, and back into the line 122. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 905 by natural convection.

[0093] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 12 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0094] The system 900 is operable in other operating modes than those shown in FIGS. 9-12 and described above. For example, the system 900 is operable in a dedicated water heating mode, as shown in FIG. 4 and described above for the system 100. In the dedicated water heating mode of the system 900, the reversing valves 106, 108, 110 are each in the first position and the first and second three-way valves 904, 906 are each in the first (non-bypass) position. In some examples, the system 900 is also operable in a space heating only mode or a space cooling only mode. In the space heating only and space cooling only operating modes, the heat pump 902 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). The system 900 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 902 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 902 demand, as described above.

[0095] Description of the controller 64 with reference to FIGS. 2-4 applies to the controller 64 of the system 900 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 900 using a control algorithm shown in FIGS. 5-8 and described above.

[0096] FIG. 13 is a flow diagram 1300 of another example control algorithm according to which the controller 64 controls the system 900 when the heat pump 902 is operating in a space heating mode (as shown in FIG. 10). As described above, during the space heating mode, there is a risk of frost building up on the outdoor coils of the outdoor heat exchanger 70, and the heat pump 902 is periodically operated in a defrost mode to remove the frost. The controller 64 determines at 1302 whether there is a demand for a defrost mode operation (or defrost cycle). For example, the controller 64 determines 1302 whether there is a demand for a defrost based on whether a pre-determined period of time has elapsed since the last defrost cycle.

[0097] When a demand for the defrost cycle occurs, the controller 64 initiates the defrost cycle at 1306. An example of a defrost mode operation is shown in FIG. 11. The controller 64 positions 1308 each of the first reversing valve 106 and the network of valves 907 of the heat pump 902 as shown in FIG. 11, turns off the indoor fan 76 at 1312, and operates 1310 the outdoor heat exchanger 70 as a condenser such that compressed, hot working fluid flows through the outdoor coils for the defrost operation. The outdoor fan 78 may be idle (e.g., turned off) to enhance the defrost operation on the outdoor coils. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode.

[0098] During the defrost cycle initiated at 1306, the controller 64 also determines whether to operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36. As described above, during a defrost mode operation, there may not be an immediate need for water heating in the water heater 14 (e.g., as determined at 504 of FIG. 5). This may signal that there is hot water available in the water heater 14 to provide heating to the working fluid in the loop 105 via the WRHX 36. Accordingly, during the defrost cycle, at 1314, the controller 64 may operate (e.g., turn on) the water pump 56 and position the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, such that the hot water heats the working fluid in the line 122 before the working fluid is directed back towards the compressor 72. Alternatively, in some examples, the controller 64 may determine that there is not hot water available in the water heater 14 to heat the working fluid in the loop 105 when the heat pump 102 is in the defrost cycle. For example, at 1316, when the temperature of the water exiting the tank 26 (or another condition of the water heater 14) does not meet the predefined criterion, this may signal that there is not hot water available for heating the working fluid. In these situations, at 1318, the controller 64 does not operate the water pump 56, or turns off the water pump 56, such that a suitable level of hot water in the tank 26 is maintained to fulfill hot water demands in the indoor space. When the water pump 56 is turned off at 1318, and the demand for the defrost cycle is still active, the controller 64 may operate (e.g., turn on) the indoor fan 76 such that heat can be absorbed into the working fluid at the indoor heat exchanger 68. The controller 64 then reverts to operation 1302, operation 1306, operation 1316, or operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0099] When the controller 64 determines (at 1320) that the demand for the defrost mode operation of the heat pump 902 terminates (e.g., after a pre-determined defrost duration), or when the controller 602 determines that there is not a demand for a defrost cycle at 1302, the controller 64 initiates (or continues) a space heating mode of the heat pump 902. In the example flow diagram, the controller 64 makes a series of determinations at 1304 and 1322 to determine whether to initiate the space heating mode of FIG. 10, in which both the indoor heat exchanger 68 and the outdoor heat exchanger 70 are operated, or the thermosiphon (or compressor-free) space heating mode of FIG. 12, in which the outdoor components of the heat pump 902 are inactive and the working fluid is driven through the loop 905 by gravity and a temperature and / or pressure differential between the indoor heat exchanger 68 and the WRHX 36 as described above. At 1304, the controller 64 determines whether an outside condition (e.g., ambient temperature measured by the sensor 136) meets or exceeds a predefined or predetermined criterion (e.g., a threshold or predetermined temperature value). In the example flow diagram 1300, the controller 64 determines 1304 whether the ambient temperature is greater than 45° F.

[0100] When the controller 64 determines 1304 that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is not greater than 45° F.), the controller 64 initiates the space heating mode of FIG. 10. In this space heating mode, as shown in FIG. 10, the controller 64 positions 1326 each of the first reversing valve 106, the second reversing valve 108, and the third reversing valve 108 in the first position, positions 1328 the first and second three-way valves 904, 906 in the first (non-bypass) position, operates 1330 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and operates 1332 the outdoor heat exchanger 70 as the evaporator of the heat pump 102 and the outdoor fan 78 to force the outlet air stream 82 across the outdoor coils. At 1334, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues through the control algorithm of the flow diagram 1300 at 1336 described below, or reverts to operation 1304 to determine whether the thermosiphon space heating mode is available, or another suitable operation to enable the controller 64 to function as described. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 902 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0101] When the controller 64 determines 1304 that the outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), the controller 64 determines 1322 whether there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 12. This can be determined as described above, for example, by determining 1322 that the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid. When the controller 64 determines that there is hot water available at 1322, the controller 64 initiates the thermosiphon space heating mode at 1336. When the controller 64 determines that there is not hot water available at 1322, the controller 64 initiates 1324 the space heating mode of FIG. 10 as described above.

[0102] In the thermosiphon space heating mode initiated at 1336, as shown in FIG. 12, the controller 64 positions 1338 the third reversing valve 108 in the first position, positions 1340 the first and second three-way valves 904, 906 in the second (bypass) position, operates 1342 (e.g., turns on) the water pump 56 and positions the three-way valves 42, 44 to circulate water from the tank 26 through the water loop 34 and the WRHX 36, operates 1344 the indoor heat exchanger 68 as the condenser of the heat pump 102 and the indoor fan 76 to force the inlet air stream 80 across the indoor coils, and fully opens 1346 (or bypasses) the expansion device 20. As described above, in the thermosiphon space heating mode, the compressor 72 and the outdoor heat exchanger 68 are isolated from the working fluid and these components may be idle or turned off when the thermosiphon space heating mode is initiated 1336. At 1348, the controller 64 determines whether the demand for the space heating mode is still active. If so, the controller 64 continues to operate the system 900 in the thermosiphon space heating mode, or reverts to operation 1304 to determine whether the thermosiphon space heating mode is still available. If the demand for the space heating mode has terminated, then the controller 64 to reverts to 506 (FIG. 5) to determine the requested operating mode of the heat pump 902 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0103] At 1350, while the space heating mode initiated at 1324, the controller 64 determines whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). When the controller 64 determines 1350 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 905 to heat water in the loop 34 via the WRHX 36. This controls (maintains) the ability of the heat pump 902 to provide the additional heating of the inlet air stream 80. In response, the controller 64 does not operate the water heater 14 to flow water through the water loop 34 and WRHX 36, irrespective of any demand for heating of water in the water heater 14. In this way, as described above, the controller 64 is programmed such that it is biased towards balancing the ability of the heat pump 902 to fulfill its requirements and the ability of the water heater 14 to fulfill its requirements. The controller 64 then continues to operate the system 900 in the space heating mode of FIG. 10, reverts to operation 1304 to determine whether the thermosiphon space heating mode is available, or reverts to operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0104] When the controller 64 determines 1350 that there is not a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 meets the setpoint temperature), then the controller determines that there is availability for using the working fluid in the loop 905 to heat water in the loop 34 via the WRHX 36. At 1352, the controller 64 determines whether there is a need for water heating in the water heater 14. This can be determined at 1352 as described above, for example, by monitoring the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14. When the controller 64 determines 1352 that there is not a need for water heating in the water heater 14, the controller 64 continues to operate the heat pump 902 in the space heating mode and, at 1354, controls the water heater 14 to not flow water through the WRHX 36 (e.g., by maintaining the pump 56 in an idle state or turning off the pump 56). The controller 64 then continues to operate the system 900 in the space heating mode of FIG. 10, or reverts to any one of operation 1350, operation 1352, operation 1304, or operation 506 of FIG. 5 for further instruction on how to control the system 900, or another suitable operation to enable the controller 64 to function as described.

[0105] When the controller 64 determines 1352 that there is a need for water heating in the water heater 14, at 1356 the controller 64 initiates a water heating operation by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and positioning the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, at 1356 the controller 64 controls the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. During the water heating operation initiated at 1356, the controller 64 also continues to monitor at 1358 whether there is a demand for additional heating of the inlet air stream 80 (e.g., based on a temperature measured at the sensor 138 compared to a predetermined or user specified setpoint temperature for the space heating mode). If there is not a demand for additional heating of the inlet air stream 80, the water heating operation initiated at 1356 may continue until there is no longer a need for water heating in the water heater 14. When the controller 64 determines 1356 that there is a demand for additional heating of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is below the setpoint temperature), the controller 64 determines that there is no availability for using the working fluid in the loop 105 to heat water in the loop 34 via the WRHX 36. In response, the controller 64 controls the water heater 14 to stop flowing water through the water loop 34 and WRHX 36 (e.g., by turning off the pump 56), irrespective of the demand for water heating of water in the water heater 14 determined at 1356. The controller 64 may then revert to operation 1304, operation 1350, operation 1352, or operation 506 of FIG. 5, or another suitable operation to enable the controller 64 to function as described.

[0106] FIGS. 14 and 15 depict a third example of an integrated heat pump-water heater system 1400 that includes a heat pump 1402 operable in multiple operating modes and the water heater 14 integrated with the heat pump 1402. The heat pump 1402 includes elements and components that are included in the heat pump, the heat pump 102 of FIGS. 2-4, and the heat pump 902 of FIGS. 9-12, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0107] In this example, the system 1400 includes the first reversing valve 106 and a network of valves 1407 on a working fluid loop 1405 of the heat pump 1402 to control flow of a working fluid (e.g., refrigerant) through the loop 1405. The first reversing valve 106 is operable (or positionable) as described above to direct the flow of the working fluid exiting the compressor 72 through the working fluid loop 1405 based on an operating mode (e.g., space heating or space cooling) of the heat pump 1402. The network of valves 1407 is connected to the first reversing valve 106 and, in this example, includes six solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 and six three-way valves 1414, 1416, 1418, 1420, 1422, and 1424, each of which are independently operable (or positionable) to direct the flow of the working fluid between the first reversing valve 106 and the indoor heat exchanger 68 based on the operating mode of the heat pump 902, as described above for the network of valves 107 in FIGS. 2-4 and the network of valves 907 in FIGS. 9-12. The system 900 is operable in the operating modes described above for the system 100 and the system 900, and includes the functionality and advantages of the system 100 and the system 900. The six solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 and six three-way valves 1414, 1416, 1418, 1420, 1422, and 1424 are operable (positionable) to direct working fluid through the loop similar to the network of valves 907 of FIGS. 9-12.

[0108] In the example system 1400, the network of valves 1407 is positioned as follows. A first three-way valve 1414 is positioned on the line 122 and a second three-way valve 1416 is positioned at a junction between the line 120 and a bypass line 1426. The first and second three-way valves 1414, 1416 are connected by a bypass line on which a third solenoid valve 1406 is positioned. A third three-way valve 1418 is positioned at a junction between the line 126, the bypass line 1426, and a bypass line on which a second solenoid valve 1404 is positioned. A fourth three-way valve 1420 is positioned at a junction between the line 122, the bypass line on which the second solenoid valve 1404 is positioned, and a bypass line on which a fourth solenoid valve 1408 is positioned. A fifth three-way valve 1422 is positioned at a junction between the line 128, the line 124, and the bypass line on which the fourth solenoid valve 1408 is positioned. A sixth three-way valve 1424 is positioned at a junction between the line 118, the line 124, and a bypass line on which a sixth solenoid valve 1412 is positioned. A first solenoid valve 1403 is positioned on the line 124 proximate the sixth three-way valve 1424. A fifth solenoid valve 1410 is positioned on the bypass line 1426, between the second and third three-way valves 1416, 1418.

[0109] Referring to FIG. 14, in a space heating mode of the heat pump 1402, each of the indoor fan 76 and the outdoor fan 78 are operated to force the respective air streams 80, 82 across the coils. The indoor heat exchanger 68 operates as the condenser, heating the inlet air stream 80, and the outdoor heat exchanger 70 operates as the evaporator, absorbing heat from the outdoor air stream 82. The first reversing valve 106 is in the first position, and the network of valves 1407 are positioned to direct the working fluid through the loop 1405 as follows: working fluid exiting the compressor 72 flows via the discharge line 112 towards and through the first reversing valve 106, into the line 116 towards and through the sixth three-way valve 1424, into the sixth solenoid valve bypass line, through the sixth solenoid valve 1412 and the first three-way valve 1414, into the line 122 towards and through the WRHX 36, through the fourth three-way valve 1420 and into the fourth solenoid valve bypass line, through the fourth solenoid valve 1420 and the fifth three-way valve 1422, into the line 128 towards and through the indoor heat exchanger 68, into the line 126 towards and through the expansion device 20, into the bypass line 1426 through the fifth solenoid valve 1410, through the second three-way valve 1416, into the line 120 towards and through the outdoor heat exchanger 70, into the line 114 and through the first reversing valve 106, and into the suction line 118 towards the compressor 72. In the space heating mode of FIG. 14, each of the first solenoid valve 1403, the second solenoid valve 1404, and the third solenoid valve 1406 are closed, which isolates the lines on which these solenoid valves are positioned.

[0110] In both the space heating mode of FIG. 14, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0111] FIG. 15 depicts the system 1400 in a defrost mode, similar to the defrost mode described above for the system 900 with reference to FIG. 11. As described above, during space heating, the heat pump 1402 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, the first reversing valve 106 is in the second position, and the network of valves 1407 has the same position as the space heating mode of FIG. 14. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The network of valves 1407 enable the working fluid to flow through the same lines of the loop 1405 as described above with reference to FIG. 14, and the first reversing valve 106 in the second position directs the working fluid to flow in the opposite direction relative to the space heating mode of FIG. 14.

[0112] In the defrost mode of FIG. 15, as described above for the defrost mode of FIG. 11, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 1402 is in the defrost mode as described above with reference to FIG. 6 and FIG. 11. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIG. 6 and FIG. 11, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0113] The system 1400 is operable in other operating modes than those shown in FIGS. 14 and 15 and described above. For example, the system 1400 is operable in a space cooling and water heating mode, as shown in FIG. 9, a thermosiphon space heating mode, as shown in FIG. 12, and a dedicated water heating mode, as shown in FIG. 4. In the space cooling mode of the system 1400, the first solenoid valve 1403, the second solenoid valve 1404, and the third solenoid valve 1406 are closed, and each of the fourth solenoid valve 1408, the fifth solenoid valve 1410, and the sixth solenoid valve 1412 are energized (open). In the thermosiphon space heating mode of the system 1400, the first solenoid valve 1403, the second solenoid valve 1404, and the sixth solenoid valve 1412 are closed, each of the third solenoid valve 1406, the fourth solenoid valve 1408, and the fifth solenoid valve 1410 are energized (open), and the expansion device 20 is fully open (or bypassed). In some examples, the system 1400 is also operable in a space heating only mode or a space cooling only mode. In the space heating only and space cooling only operating modes, the heat pump 1402 conditions the inlet air stream 80 as described above while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). In some examples, the system 1400 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 1402 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 1402 demand, as described above.

[0114] Description of the controller 64 with reference to FIGS. 1-13 applies to the controller 64 of the system 1400 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 1400 using the control algorithms shown in FIGS. 5-8 and 13 and described above.

[0115] Table 1 below provides a summary of example operating modes of the system 1400, the positioning of the first reversing valve 106 and the solenoid valves 1403, 1404, 1406, 1408, 1410, and 1412 in each operating mode, and the components of the system 1400 that are operated in each mode.TABLE 1Overview of Control of the System 1400 of FIGS. 14 and 15Task ScenarioLocationJob / Energy SourceMitigationSpaceDefrostIntDeviceSpaceSpaceHeatingDefrostOD CoilWaterIndependentControlCoolingHeatingw / HotOD Coilw / HotHeatingWaterMitigationSystem Operating Modesw / DXw / DXWaterw / DXWaterw / DXHeatingDevice1Space Cooling Only✓2Space Cooling + Partial✓✓✓Preheating Cold Water Supply3Space Cooling + Preheating✓✓Cold Water Supply4Space Cooling + Standby Water✓✓Heating5Space Heating Only✓6Space Heating + Preheating✓✓Cold Water Supply7Space Heating + Standby Tank✓✓Water Heating8Space Heating: HP + Hydronic✓✓Refr Heating9Hydronic Thermosiphon Space✓Heating10Defrost of Outdoor Coil Using✓✓HP + Water to Heat Refrigerant11Defrost of Outdoor Coil Using✓HP12Dedicated Water Heating:✓Preheating Cold Water Supply13Dedicated Water Heating:✓Standby Tank using HP14Dedicated Water Heating:✓Standby TankTABLE 1Overview of Control of the System 1400 of FIGS. 14 and 15Mitigation OptionsINDOORSOUTDOORSHot WaterTstat / TankTstat / FurnaceTstat / ControllerTstat / FurnaceBoard +FurnaceSecondary IWH Kit ControllerWaterFurnaceBoardOD FanBoardSole-Sole-Sole-Sole-Sole-Sole-TankBoardRevers-ControlIndoornoidnoidnoidnoidnoidnoidWaterSupp HeatCom-ingOutdoorBlowerValve 1Valve 2Valve 3Valve 4Valve 5Valve 6EXVPumpSourcepressorValveFanONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1ON% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFONONPos 1ON% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1CYC% OPENONOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDONOFFONPos 1CYC% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENONCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENONCLOSEDCLOSEDOPENOPENOPENCLOSEDFULL OPENONOFFOFFPos 1OFFOFFOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDONOFFONPos 1OFF% OPENOFFOPENOPENOPENCLOSEDCLOSEDCLOSEDCONTROLLEDOFFOFFONPos 1OFF% OPENOFFCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDOFFOFFONPos 2ON% OPENOFFCLOSEDCLOSEDCLOSEDOPENOPENOPENCONTROLLEDONOFFONPos 2ON% OPENOFFCLOSEDCLOSEDCLOSEDCLOSEDCLOSEDCLOSEDN / AOFFONOFFPos 1OFFFIGS. 16-19 depict a fourth example of an integrated heat pump-water heater system 1600 that includes a heat pump 1602 operable in multiple operating modes and the water heater 14 integrated with the heat pump 1602. The heat pump 1602 includes similar elements and components as the heat pump 12 of FIG. 1 and the heat pump 102 of FIGS. 2-4, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4.

[0117] In this example, the system 1600 includes the first reversing valve 106 on the loop, without a network of valves connected to the first reversing valve 106. The first reversing valve 106 is positionable to reverse the direction of flow of working fluid through a working fluid loop 1605. The lines of the working fluid loop 1605 are consolidated in this example, similar to FIG. 1. The WRHX 36 is positioned on the line 116, which connects the first reversing valve 106 and the indoor heat exchanger 68. The expansion device 20 is positioned on the line 120, which connects the indoor heat exchanger 68 and the outdoor heat exchanger 70.

[0118] FIG. 16 depicts the system 1600 in a space heating mode. The first reversing valve 106 is in the first position, the indoor heat exchanger68 is operated as the condenser, and the outdoor heat exchanger 70 is operated as the evaporator. The first reversing valve 106 in the first position directs the working fluid exiting the compressor 72 via the line 112 into the line 116 and through the WRHX 36. The working fluid then flows through the indoor exchanger 68, into the line 120, through the expansion device 20, towards and through the outdoor heat exchanger 70, into the line 114 and through the reversing valve 106, into the suction line 118 towards the compressor 72. In the space heating mode of the heat pump 1602, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0119] FIG. 17 depicts the system 1600 in a dedicated water heating mode, similar to FIG. 4. As described above, the system 1600 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58 and / or to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the first reversing valve 106 is in the first position and the working fluid flows as described above for the space heating mode of FIG. 16. The outdoor heat exchanger 70 is operated as the evaporator, as described above for the space heating mode of FIG. 16. The indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 1602. The water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0120] FIG. 18 depicts the system 1600 in a space cooling only mode. The first reversing valve 106 is in the second position, the indoor heat exchanger 68 is operated as the evaporator, and the outdoor heat exchanger 70 is operated as the condenser. The first reversing valve 106 in the second position directs the working fluid in the opposite direction through the loop 1605 as the space heating mode of FIG. 16. The working fluid exiting the compressor 72 via the line 112 is directed by the first reversing valve 106 into the line 114 and through the outdoor heat exchanger 70. The working fluid then flows into the line 120, through the expansion device 20, towards and through the indoor heat exchanger 68, into the line 116 towards and successively through the WRHX 36 and the reversing valve 106, into the suction line 118 towards the compressor 72. In the space cooling only mode, little to no heat is transferred in the WRHX 36, and the water heater 14 is controlled by the controller 64 to not flow water through the loop 34.

[0121] FIG. 19 depicts the system 1600 in a defrost mode. As described above, during space heating, the heat pump 1602 can be periodically operated in a defrost cycle, in which the space heating mode is temporarily ceased and the flow of working fluid is reversed to flow compressed, hot working fluid through the outdoor heat exchanger 70, raising the temperature of the outdoor coils to remove frost. In the defrost operating mode of this example, the indoor fan 76 and the outdoor fan 78 are both turned off, and the first reversing valve 106 is in the second position. The expansion device 20 may also be operated (positioned) in a fully opened state and / or bypassed in the defrost mode. The reversing valve 106 in the second position directs the working fluid through the loop 905 as described above for the space cooling mode of FIG. 18.

[0122] In the defrost mode of FIG. 19, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to heat the working fluid in the line 122, upstream from the compressor 72. The water heater 14 is operated for heating the working fluid when the heat pump 1602 is in the defrost mode as described above with reference to FIGS. 6 and 11. For example, the controller 64 can control the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. As described above with reference to FIGS. 6 and 11, in some examples, if the controller 64 determines that a monitored condition of the water heater 14 (e.g., a temperature of the water exiting the tank 26, a temperature of the water in the tank 26, a level of the water in the tank 26, or another suitable operating condition of the water heater 14) does not meet a predefined criterion, this may signal that there is not hot water available for heating the working fluid and, in response, the controller 64 may not operate the water pump 56 to provide heating to the working fluid in the defrost mode. This may maintain a suitable level of hot water in the tank 26 and the ability of the water heater 14 to fulfill hot water demands in the indoor space.

[0123] The system 1600 is operable in other operating modes than those shown in FIGS. 16-19 and described above. For example, the system 1600 is operable in a space heating only mode in which, like the space cooling only mode of FIG. 18, the heat pump 1602 conditions the inlet air stream 80 while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). In some examples, the system 1600 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 1602 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 1602 demand, as described above.

[0124] Description of the controller 64 above applies to the controller 64 of the system 1600 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 1600 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to exclude any operations related to control of a network of valves that is not included in the system 1600 and the functionality that the network of valves provides. For example, in the system 1600, water heating may not be available when the heat pump 1602 is in a space cooling mode. As such, referring to FIG. 7, the controller 64 may not perform operations 714-720 for the system 1600, and instead may always operate the water pump 56 in an idle or off state when the system 1600 is in the space cooling mode.

[0125] FIGS. 20-22 depict a fifth example of an integrated heat pump-water heater system 2000 that includes a heat pump 2002 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2002. The heat pump 2002 includes similar elements and components as the heat pump 12 of FIG. 1, the heat pump 102 of FIGS. 2-4, and the heat pump 1602 of FIGS. 16-19, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4 and FIGS. 16-19.

[0126] In this example, the system 2000 includes the first reversing valve 106 and a network of valves 2007 on a working fluid loop 2005 of the heat pump 2002 to control flow of a working fluid (e.g., refrigerant) through the loop 2005. The network of valves 2007 is connected to the first reversing valve 106 and includes a first three-way valve 2004 positioned on the line 120 and a second three-way valve 2006 positioned on the line 116. The first and second three-way valves 2004, 2006 are connected by a bypass line 2008. The WRHX 36 is positioned on the line 116 between the bypass line 2008 and the indoor heat exchanger 68.

[0127] FIG. 20 depicts the system 2000 in a space heating mode. The first reversing valve 106 is in the first position, the indoor heat exchanger 68 is operated as the condenser, and the outdoor heat exchanger 70 is operated as the evaporator. The first reversing valve 106 in the first position directs the working fluid through the loop as described above for FIG. 16. The first and second three-way valves 2004, 2006 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 116 or line 120 into the bypass line 2008.

[0128] In the space heating mode of the heat pump 2002, the water heater 14 is controlled by the controller 64 to continuously or periodically cycle water through the WRHX 36 to supply or replenish hot water to the water heater 14. The water heater 14 is operated as described above. For example, in response to a determined need for water heating in the water heater 14, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0129] FIG. 21 depicts the system 2000 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 2004, 2006 and the bypass line 2008. The thermosiphon space heating mode is similar to that described above for FIG. 12. In the thermosiphon space heating mode, the outdoor components of the heat pump 2002, including the compressor 72 and the outdoor fan 78, are idle. The network of valves 2007 is operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 2002. To enable a thermosiphon or compressor-free mode of the heat pump 2002, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 2005 using natural convection rather than by mechanical force. The system 2005 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0130] In the thermosiphon or compressor-free mode of FIG. 21, each of the three-way valves 2004, 2006 is in a second (bypass) position to allow the working fluid to flow through the bypass line 2008 between the lines 116 and 120. The three-way valves 2004, 2006 in the second position restrict flow of the working fluid in the lines 116, 120 to within a portion between the indoor heat exchanger 68 and the valves 2004, 2006. As such, the lines 112, 114, and 118, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2005. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 21, in the thermosiphon or compressor-free mode, the three-way valves 2004, 2006 direct the working fluid through the loop 2005 as follows: working fluid flows through the line 116 and the WRHX 36, towards and through the indoor heat exchanger 68, into the line 120 towards and successively through the expansion device 20 and the first three-way valve 2004, into the bypass line 2008 towards and through the second three-way valve 2006, and back into the line 116. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2005 by natural convection.

[0131] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 21 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0132] FIG. 22 depicts the system 2000 in a space cooling only mode. The first reversing valve 106 is in the second position, the indoor heat exchanger 68 is operated as the evaporator, and the outdoor heat exchanger 70 is operated as the condenser. The first reversing valve 106 in the second position directs the working fluid in the opposite direction through the loop 2005 as the space heating mode of FIG. 20, and in the flow direction as described above for FIG. 18. The first and second three-way valves 2004, 2006 are each in the first (non-bypass) position, such that the working fluid is not redirected from either line 116 or line 120 into the bypass line 2008. In the space cooling only mode, little to no heat is transferred in the WRHX 36, and the water heater 14 is controlled by the controller 64 to not flow water through the loop 34.

[0133] The system 2000 is operable in other operating modes than those shown in FIGS. 20-22 and described above. For example, the system 2000 is operable in a space heating only mode in which, like the space cooling only mode of FIG. 22, the heat pump 2002 conditions the inlet air stream 80 while the water heater 14 is idle (e.g., little to no water flows through the water loop 34). The system 900 is also operable in a space heating / cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 2002 via the WRHX 36 in the space heating and / or space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 2002 demand, as described above.

[0134] Description of the controller 64 above applies to the controller 64 of the system 2000 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2000 using the control algorithms shown in FIGS. 5-8 and 13 and described above, which may be modified as appropriate related to control of the network of valves 2007, specifically the three-way valves 2004, 2006 and the functionality that the network of valves provides. Referring to FIG. 13, the controller 64 determines whether to operate the system 2000 in the space heating mode of FIG. 20 or the thermosiphon space heating mode based the determinations at 1304 and 1322. In the system 2000, water heating may not be available when the heat pump 2002 is in a space cooling mode. As such, referring to FIG. 7, the controller 64 may not perform operations 714-720 for the system 2000, and instead may always operate the water pump 56 in an idle or off state when the system 2000 is in the space cooling mode.

[0135] FIG. 23 depicts a sixth example of an integrated heat pump-water heater system 2300 that includes a heat pump 2302 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2302. The heat pump 2302 includes similar elements and components as the heat pump 12 of FIG. 1, the heat pump 102 of FIGS. 2-4, the heat pump 1602 of FIGS. 16-19, and the heat pump 2002 of FIGS. 20-22, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 1-4 and FIGS. 16-22.

[0136] In this example, the system 2300 includes the first reversing valve 106 and a network of valves 2307 on a working fluid loop 2305 of the heat pump 2302 to control flow of a working fluid (e.g., refrigerant) through the loop 2305. The network of valves 2007 is connected to the first reversing valve 106 and includes three solenoid valves 2304, 2306, and 2308, which are operable to provide similar functionality as the first three-way valve 2004 and the second three-way valve 2006 of the system 2000 of FIGS. 20-22. A first solenoid valve 2304 is positioned on the line 116 between the first reversing valve 106 and the bypass line 2008. A second solenoid valve 2306 is positioned on the line 120 between the outdoor heat exchanger 70 and the bypass line 2008. A third solenoid valve 2308 is positioned on the bypass line 2008. Similar to the system 2000, in this example, the WRHX 36 is positioned on the line 116, between the bypass line 2008 and the indoor heat exchanger 68.

[0137] The system 2300 operates similar to the system 2000. For example, the system 2300 is operable in a space heating mode (shown in FIG. 23) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space heating mode of FIG. 23, the first reversing valve 106 is in the first position and each of the first and second solenoid valves 2304, 2306 are energized to allow the working fluid to flow through the loop 2305 as described above for FIG. 20, and the third solenoid valve 2308 is de-energized or off to prevent flow of the working fluid through the bypass line 2008. In the space heating mode of FIG. 23, the water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36.

[0138] The system 2300 is operable in the other operating modes described above for the system 2000 of FIGS. 20-22. For example, the system 2300 is operable in a thermosiphon space heating mode, a space cooling only mode, a space heating only mode, and in a space heating / cooling and hydronic heating mode. Description of the controller 64 above with reference to the system 2000 applies to the controller 64 of the system 2300 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2300 using similar control algorithms as used to control the system 2000, shown in FIGS. 5-8 and 13 and described above, which may be modified as appropriate to control the solenoid valves 2304, 2306, 2308 in a similar manner as the three-way valves 2004, 2006.

[0139] In the thermosiphon space heating mode of the system 2300, the third solenoid valve 2308 is energized to allow the working fluid to flow through the bypass line 2008 between the lines 116 and 120. The first and second solenoid valves 2304, 2306 are de-energized (off or closed) to restrict flow of the working fluid in the lines 116, 120 to within a portion between the indoor heat exchanger 68 and the valves 2004, 2006, and isolate the lines 112, 114, and 118, the first reversing valve 106, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 2304, 2306, 2308 are operated to direct the working fluid through the loop 2305 as described above with reference to FIG. 21. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2305 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 21.

[0140] FIGS. 24-26 depict a seventh example of an integrated heat pump-water heater system 2400 that includes a heat pump 2402 operable in a space cooling mode and the water heater 14 integrated with the heat pump 2402. In this example, the system 2400 is operable in a space cooling and standby water heating mode (FIG. 24), a space cooling and groundwater heating mode (FIG. 25), and a space cooling only mode (FIG. 26). The heat pump 2402 does not include the first reversing valve 106 or a network of valves in this example, and is configured similar to the heat pump 12 of FIG. 1, except that the WRHX 36 and the expansion device 20 are on a common line 2404 of a working fluid loop 2405 that extends between the indoor heat exchanger 68 and the outdoor heat exchanger 70. The expansion device 20 is positioned between the WRHX 36 and the indoor heat exchanger 68. The working fluid loop 2405 also includes a suction line 2406 extending between the indoor heat exchanger 68 and the compressor 72, and a discharge line 2408 extending between the compressor 72 and the outdoor heat exchanger 70. In this example, the suction line accumulator 74 is positioned indoors on the suction line 2406, upstream from the compressor 72. The compressor 72 and the outdoor heat exchanger 70 are each positioned outdoors, and the lines 2404, 2406 extend through the partition 11.

[0141] In each space cooling mode of FIGS. 24-26, the working fluid exiting the compressor 72 flows through the discharge line 2408 towards and through the outdoor heat exchanger 70, into the line 2404 towards and successively through the WRHX 36 and the expansion device 20, through the indoor heat exchanger 68 and into the suction line 2406 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 2402 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80.

[0142] Description of the controller 64 above applies to the controller 64 of the system 2400 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 2400 using the control algorithms shown in FIGS. 5 and 7 and described above, which may be modified as appropriate to exclude any operations related to control of a reversing valve and a network of valves that is not included in the system 2400 and the functionality that the reversing valve and the network of valves provide. The system 2400 does not operate in a space heating mode or a dedicated water heating mode, and as such, the control algorithms of FIGS. 6 and 8 are not implemented in this example. The system 900 may be operable in a space cooling and hydronic heating mode, in which the water heater 14 is controlled to provide supplemental heating to the heat pump 2402 via the WRHX 36 in the space cooling mode when conditions in the water heater 14 allow and conditions in the heat pump 2402 demand, as described above.

[0143] In the space cooling mode of FIGS. 24-26, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 24), the groundwater heating mode (FIG. 25), or neither (FIG. 26, in which the system 2400 provides space cooling only). Referring to FIGS. 7 and 24, the controller 64 may operate the water heater 14 in the standby water heating mode and / or the groundwater heating mode when the controller 64 determines at 712 that there is a need for water heating in the water heater 14. In response, the water pump 56 is controlled to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and the three-way valves 42, 44 are positioned to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26 and / or the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. If the controller 64 determines at 712 that there is not a need for water heating in the water heater 14, the controller 64 can operate the water heater 14 in the groundwater heating mode. Alternatively, the controller 64 may control the water heater 14 to not flow water through the loop 34, such that the system 2400 is in the space cooling only mode. The space cooling only mode may be appropriate, for example, when the controller 64 determines that there is a demand for additional cooling of the inlet air stream 80 (e.g., when the temperature measured at the sensor 138 is above a setpoint temperature), and the controller 64 determines that there is no availability for using the working fluid in the loop 2405 to heat water in the loop 34 via the WRHX 36.

[0144] The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 2400, depending on the ambient conditions as measured by the sensor 136. As described above, in the space cooling mode, the ability of the working fluid to transfer heat into the water in the loop 34 varies based on the outside temperature conditions, which affect the amount of heat transfer that occurs between the working fluid and the outside air stream 82 in the outdoor heat exchanger 70. Smaller heat transfer in the outdoor heat exchanger 70, which is more likely to occur in hot temperature outside conditions, provides more capability of the working fluid in the line 122 to reject heat into the water loop 34 via the WRHX 36. Referring to FIG. 7, the controller 64 monitors at 716 the ability of the working fluid exiting the outdoor heat exchanger 70 to transfer heat into the water in the loop 34 via the WRHX 36 during the water heating operation initiated at 714. For example, the controller 64 monitors 716 the temperature of the working fluid exiting the outdoor heat exchanger 70 in the line 2404 via the sensor 130. Additionally, or alternatively, the controller 64 may monitor 716 any suitable operating condition of the heat pump 2402 indicative of the ability of the working fluid to transfer heat via the WRHX while the heat pump 2402 is in the space cooling mode. For example, the controller 64 monitors 716 the ambient temperature via the sensor 136 and / or a temperature of the working fluid in the 122 upstream from the WRHX 36. At 718, the controller 64 determines whether the monitored 716 condition satisfies a predetermined criterion that is indicative of effective heat transfer between the working fluid in the line 2404 and the water in the loop 34 via the WRHX 36. For example, the controller 64 determines whether the monitored 716 temperature of the working fluid in the line 2404 exiting the outdoor heat exchanger 70 meets or exceeds a predetermined temperature value (e.g., 130° F.) that is indicative of effective heat transfer. If the monitored 716 condition (e.g., temperature) meets or exceeds the predetermined criterion (e.g., the predetermined value), the controller 64 takes no further action and allows operation to continue. If the monitored 716 condition (e.g., temperature) is below the predetermined criterion (e.g., the predetermined temperature value), the controller 64 may cycle, bypass, and / or operate as idle the outdoor fan 78 at 720.

[0145] FIGS. 27-30 depict an eighth example of an integrated heat pump-water heater system 2700 that includes a heat pump 2702 operable in multiple operating modes and the water heater 14 integrated with the heat pump 2702. The heat pump 2702 includes similar elements and components as the heat pump 2402 of FIGS. 24-26, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0146] In this example, in addition to the elements and components of the system 2400 of FIGS. 24-26, the system 2700 includes two three-way valves 2704, 2706 on a working fluid loop 2705 of the heat pump 2702 to control flow of a working fluid (e.g., refrigerant) through the loop 2705. The three-way valves 2704, 2706 provide additional functionality to the integrated system 2700 relative to the system 2400 of FIGS. 24-26. A first three-way valve 2704 is positioned on the line 2404 between the outdoor heat exchanger 70 and the WRHX 36. A second three-way valve 2706 is positioned on the suction line 2406 between the indoor heat exchanger 68 and the suction line accumulator 74. The first and second three-way valves 2704, 2706 are connected by a bypass line 2708.

[0147] FIGS. 27-29 depict the system 2700 in a space cooling mode, similar to the modes of FIGS. 24-26. As described above for each space cooling mode of FIGS. 24-26, in the space cooling mode of FIGS. 27-29, the working fluid exiting the compressor 72 flows through the discharge line 2408 towards and through the outdoor heat exchanger 70, into the line 2404 towards and successively through the WRHX 36 and the expansion device 20, through the indoor heat exchanger 68 and into the suction line 2406 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 2402 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80. The first and second three-way valves 2704, 2706 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 2404 or line 2406 into the bypass line 2708.

[0148] Description of the controller 64 above and the functions executed by the controller 64 for the space cooling modes of FIGS. 24-26 applies to the controller 64 of the system 2700. For example, in the space cooling mode of FIGS. 27-29, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 27), the groundwater heating mode (FIG. 28), or neither (FIG. 29, in which the system 2700 provides space cooling only) as described above. The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 2700, depending on the ambient conditions as measured by the sensor 136 as described above.

[0149] FIG. 30 depicts the system 2700 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 2704, 2706 and the bypass line 2708. The thermosiphon space heating mode is similar to that described above for FIGS. 12 and 21. In the thermosiphon space heating mode, the outdoor components of the heat pump 2702, including the compressor 72 and the outdoor fan 78, are idle. The three-way valves 2704, 2706 are operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 2702. To enable a thermosiphon or compressor-free mode of the heat pump 2702, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 2705 using natural convection rather than by mechanical force. The system 2700 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0150] In the thermosiphon or compressor-free mode of FIG. 30, each of the three-way valves 2704, 2706 is in a second (bypass) position to allow the working fluid to flow through the bypass line 2708 between the lines 2404 and 2406. The three-way valves 2704, 2706 in the second position restrict flow of the working fluid in the lines 2404, 2406 to within a portion between the indoor heat exchanger 68 and the valves 2704, 2706. As such, the line 2408, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2705. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 30, in the thermosiphon or compressor-free mode, the three-way valves 2704, 2706 direct the working fluid through the loop 2705 as follows: working fluid flows through the portion of the line 2404 between the first three-way valve 2704 and the indoor heat exchanger 68, successively through the WRHX 36, the expansion device 20, and the indoor heat exchanger 68, into the line 2406 towards and through the second three-way valve 2706, into the bypass line 2708 towards and through the first three-way valve 2704, and back into the line 2404. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 2705 by natural convection.

[0151] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 30 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0152] The controller 64 also determines whether to operate the system 2700 in the thermosiphon space heating mode of FIG. 30 based on the outside conditions and whether hot water is available in the water heater 14 for heating the working fluid in the loop 2705. This can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 30 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 2700 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 30 (e.g., at 1322 of FIG. 13), then the controller 64 does not initiate the thermosiphon space heating mode. In this example, the system 2700 may operate in conjunction with another heating source that supplies heat to the indoor space when a space heating mode is requested and the thermosiphon space heating mode of FIG. 30 is not available.

[0153] FIG. 31 depicts a ninth example of an integrated heat pump-water heater system 3100 that includes a heat pump 3102 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3102. The heat pump 3102 includes similar elements and components as the heat pump 2702 of FIGS. 27-30, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 27-30. In this example, the system 3100 includes three solenoid valves 3104, 3106, and 3108, which are operable to provide similar functionality as the three-way valves 2704, 2706 of the system 2700 of FIGS. 27-30. A first solenoid valve 3104 is positioned on the line 2404 between the outdoor heat exchanger 70 and the bypass line 2708. A second solenoid valve 3106 is positioned on the suction line 2406 between the outdoor heat exchanger 70 and the bypass line 2708. A third solenoid valve 3108 is positioned on the bypass line 2708. Similar to the system 2700, in this example, the WRHX 36 is positioned on the line 2404, between the bypass line 2708 and the indoor heat exchanger 68.

[0154] The system 3100 operates similar to the system 2700. For example, the system 3100 is operable in a space cooling mode in conjunction with standby water heating (shown in FIG. 31) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space cooling and standby water heating mode of FIG. 31, each of the first and second solenoid valves 3104, 3106 are energized to allow the working fluid to flow through the loop 3105 as described above for FIGS. 27-29, and the third solenoid valve 3108 is de-energized or off to prevent flow of the working fluid through the bypass line 2708. In the space cooling mode of the system 3100, the controller 64 operates the water heater 14 as described above for FIGS. 27-29, in a standby water heating mode (FIG. 31), the groundwater heating mode (similar to FIG. 28), or neither (similar to FIG. 29, in which the system 3100 provides space cooling only). The controller 64 also controls operation of the outdoor fan 78 during the space cooling mode of the system 3100, depending on the ambient conditions as measured by the sensor 136 as described above.

[0155] The system 3100 is operable in a thermosiphon space heating mode, similar to the thermosiphon space heating mode of the system 2700 shown in FIG. 30. In the thermosiphon space heating mode of the system 3100, the third solenoid valve 3108 is energized to allow the working fluid to flow through the bypass line 2708 between the lines 2404 and 2406. The first and second solenoid valves 3104, 3106 are de-energized (off or closed) to restrict flow of the working fluid in the lines 2404, 2406 to within the portion between the indoor heat exchanger 68 and the valves 3104, 3106, and isolate the line 2408, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 3104, 3106, 3108 are operated to direct the working fluid through the loop 3105 as described above with reference to FIG. 30. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3105 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 30.

[0156] Description of the controller 64 above with reference to the system 2700 applies to the controller 64 of the system 3100 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3100 using similar control algorithms as used to control the system 2700, which may be modified as appropriate to control the solenoid valves 3104, 3106, 3108 in a similar manner as the three-way valves 2704, 2706.

[0157] FIGS. 32-34 depict a tenth example of an integrated heat pump-water heater system 3200 that includes a heat pump 3202 operable in a space heating mode and the water heater 14 integrated with the heat pump 3202. In this example, the system 3200 is operable in a space cooling and standby water heating mode (FIG. 32), a space cooling and groundwater water heating mode (not shown), a dedicated water heating mode (FIG. 33), and a space heating only mode (FIG. 34). The heat pump 3202 does not include the first reversing valve 106 or a network of valves in this example, and is configured similar to the heat pump 2402 of FIGS. 24-26, except that the WRHX 36 and the expansion device 20 are on a different lines of a working fluid loop 3205. The WRHX 36 is positioned on a discharge line 3210 that extends from the compressor 72 to the indoor heat exchanger 68. The expansion device 20 is positioned on a line 3204 that extends the indoor heat exchanger 68 and the outdoor heat exchanger 70. The working fluid loop 3205 also includes a suction line 3206 extending between the outdoor heat exchanger 70 and the compressor 72. In this example, the accumulator 74 is positioned indoors on the line 3204, upstream from the outdoor heat exchanger 70. The compressor 72 and the outdoor heat exchanger 70 are each positioned outdoors, and the lines 3204, 3210 extend through the partition 11.

[0158] In each operating mode of the system 3200, such as those shown in FIGS. 32-34, the working fluid exiting the compressor 72 flows through the discharge line 3210 towards and successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, and into the suction line 3206 back towards the compressor 72. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3202 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. The indoor heat exchanger 68 operates as the condenser of the heat pump 3202 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80.

[0159] Description of the controller 64 above applies to the controller 64 of the system 3200 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3200 using the control algorithms shown in FIGS. 5, 6, and 8 and described above, which may be modified as appropriate to exclude any operations related to control of a reversing valve and a network of valves that is not included in the system 3200 and the functionality that the reversing valve and the network of valves provide. The system 3200 does not operate in a space cooling mode, and as such, the control algorithm of FIG. 7 is not implemented in this example.

[0160] In the space heating mode of the heat pump 3202, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 32), the groundwater heating mode (not shown), or neither (FIG. 34, in which the system 3200 provides space heating only). Referring to FIGS. 6 and 32, the controller 64 may operate the water heater 14 in the standby water heating mode (or the groundwater heating mode) when the controller 64 determines at 628 that there is not a demand for additional heating of the inlet air stream 80 and at 630 that there is a need for water heating in the water heater 14. In response, the water pump 56 is controlled to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and the three-way valves 42, 44 are positioned to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26, and / or the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36. If the controller 64 determines at 628, and / or at 636, that there is a demand for additional heating of the inlet air stream 80, and that heating of the water using the working fluid via the WRHX 36 is not available, the controller 64 controls the water heater 14 to not flow water through the loop 34, such that the system 3200 is in the space heating only mode. The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 3202 in the space heating mode via the WRHX 36 when conditions in the water heater 14 allow and conditions in the heat pump 3202 demand, as described above.

[0161] FIG. 33 depicts the system 3200 in a dedicated water heating mode, which can be initiated by the controller 64 according to the control algorithm of FIG. 8 (e.g., when the heat pump 3202 is not being used to condition the inlet air stream 80 and the controller 64 determines that there is a need for water heating in the water heater 14). As described above, for example with reference to FIG. 4, the system 3200 is operable in the dedicated water heating mode to heat water that is supplied to the water heater 14 via the water supply 58 and / or to heat water being circulated through the water loop 34 between the outlet 27 and the inlet 52 of the tank 26. In the dedicated water heating mode, the working fluid flow through the loop 3205 as described above for FIGS. 32 and 34. The outdoor heat exchanger 70 is operated as the evaporator, and the indoor heat exchanger 68 is idle (e.g., with the fan 76 turned off) and / or bypassed since no conditioning is being provided to the indoor space in this mode. As such, in this operating mode, the WRHX 36 may operate as the condenser of the heat pump 3202. The water heater 14 is operated as described above to flow water through the water loop 34 for heating the water via the WRHX 36. For example, the water pump 56 is operated (e.g., turned on) to circulate water from the tank 26 through the water loop 34 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 34 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the three-way valves 62, 44 are positioned to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 34, and the WRHX 36.

[0162] FIGS. 35-37 depict an eleventh example of an integrated heat pump-water heater system 3500 that includes a heat pump 3502 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3502. The heat pump 3502 includes similar elements and components as the heat pump 3200 of FIGS. 32-34, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above.

[0163] In this example, in addition to the elements and components of the system 3200 of FIGS. 32-34, the system 3500 includes two three-way valves 3504, 3506 on a working fluid loop 3505 of the heat pump 3505 to control flow of a working fluid (e.g., refrigerant) through the loop 3505. The three-way valves 3504, 3506 provide additional functionality to the integrated system 3500 relative to the system 3200 of FIGS. 32-34. A first three-way valve 3504 is positioned on the discharge line 3210 between the compressor 72 and the WRHX 36. A second three-way valve 3506 is positioned on the line 3204 between the indoor heat exchanger 68 and the expansion device 20. The first and second three-way valves 3504, 3506 are connected by a bypass line 3508.

[0164] FIGS. 35 and 36 depict the system 3500 in a space heating and standby water heating mode and a dedicated water heating mode, respectively, similar to the modes of FIGS. 32 and 33. As described above for each operating mode of FIGS. 35-37, in the space heating mode of FIG. 32 and the dedicated water heating mode of FIG. 33, the working fluid exiting the compressor 72 flows through the discharge line 3210 towards and successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, and into the suction line 3206 back towards the compressor 72. The first and second three-way valves 3504, 3506 are each in a first (non-bypass) position, such that the working fluid is not redirected from either line 3204 or line 3210 into the bypass line 3508. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3202 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82. In the space heating mode, the indoor heat exchanger 68 operates as the condenser of the heat pump 3202 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. In the dedicated water heating mode, the indoor fan 76 is idle or off, and the WRHX 36 may operate as the condenser.

[0165] Description of the controller 64 above and the functions executed by the controller 64 for the space heating modes and dedicated water heating mode of FIGS. 32-34 for the system 3200 applies to the controller 64 of the system 3500. For example, in the space heating mode of the heat pump 3502, the controller 64 determines whether to operate the water heater 14 in the standby water heating mode (FIG. 35), the groundwater heating mode, or neither (in which the system 3500 provides space heating only) as described above. Additionally, the controller 64 may initiate hydronic (water-to-working fluid) heating to supplement the heat pump 3502 in the space heating mode via the WRHX 36 using water in the water loop 34 when conditions in the water heater 14 allow and conditions in the heat pump 3502 demand, as described above.

[0166] FIG. 37 depicts the system 3500 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the three-way valves 3504, 3506 and the bypass line 3508. The thermosiphon space heating mode is similar to that described above for FIGS. 12, 21, and 30. In the thermosiphon space heating mode, the outdoor components of the heat pump 3502, including the compressor 72 and the outdoor fan 78, are idle. The three-way valves 3504, 3506 are operated (positioned) to bypass the outdoor components, such that the working fluid flows only through the indoor components and indoor lines of the heat pump 3502. To enable a thermosiphon or compressor-free mode of the heat pump 3502, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 3505 using natural convection rather than by mechanical force. The system 3505 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0167] In the thermosiphon or compressor-free mode of FIG. 37, each of the three-way valves 3504, 3506 is in a second (bypass) position to allow the working fluid to flow through the bypass line 3508 between the lines 3204 and 3210. The three-way valves 3504, 3506 in the second position restrict flow of the working fluid in the lines 3204, 3210 to within a portion between the indoor heat exchanger 68 and the valves 3504, 3506. As such, the line 3206, the expansion device 20, the compressor 72, and the outdoor heat exchanger 70 are isolated from flow of the working fluid in the loop 2705. The compressor 72 and the outdoor fan 78 are turned off in this operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. As shown in FIG. 37, in the thermosiphon or compressor-free mode, the three-way valves 3504, 3506 direct the working fluid through the loop 3505 as follows: working fluid flows through the portion of the line 3210 between the first three-way valve 3504 and the indoor heat exchanger 68, successively through the WRHX 36 and the indoor heat exchanger 68, into the line 3204 towards and through the second three-way valve 3506, into the bypass line 3508 towards and through the first three-way valve 3504, and back into the line 3210. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3505 by natural convection.

[0168] The water heater 14 is operated in the thermosiphon or compressor-free mode of FIG. 37 to circulate hot water in the loop 34 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 34. This prevents lowering the temperature of the water in the loop 34 which could limit the ability of the water to heat the working fluid via the WRHX 36.

[0169] The controller 64 also determines whether to operate the system 3500 in the thermosiphon space heating mode of FIG. 37 based on the outside conditions and whether hot water is available in the water heater 14 for heating the working fluid in the loop 3505. This can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 37 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 3500 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 14 for the thermosiphon space heating mode of FIG. 37 (e.g., at 1322 of FIG. 13), then the controller 64 initiates the space heating mode of the heat pump 3502 using the outdoor heat exchanger 70 as the evaporator (e.g., as shown in FIG. 35).

[0170] FIG. 38 depicts a twelfth example of an integrated heat pump-water heater system 3800 that includes a heat pump 3802 operable in multiple operating modes and the water heater 14 integrated with the heat pump 3802. The heat pump 3802 includes similar elements and components as the heat pump 3802 of FIGS. 35-37, with like elements and components indicated using like reference numerals. The water heater 14 in this example includes the elements and components as described above with reference to FIGS. 35-37. In this example, the system 3800 includes three solenoid valves 3804, 3806, and 3808, which are operable to provide similar functionality as the three-way valves 3504, 3506 of the system 3500 of FIGS. 35-37. A first solenoid valve 3804 is positioned on the discharge line 3210 between the compressor 72 and the bypass line 3508. A second solenoid valve 3806 is positioned on the line 3204 between the expansion device 20 and the bypass line 3508. A third solenoid valve 3808 is positioned on the bypass line 3508. Similar to the system 3500, in this example, the WRHX 36 is positioned on the discharge line 3210, between the bypass line 3508 and the indoor heat exchanger 68.

[0171] The system 3800 operates similar to the system 3500. For example, the system 3800 is operable in a space heating mode in conjunction with standby water heating (shown in FIG. 38) in which water can flow through the loop 34 and the working fluid is used to heat the water via the WRHX 36. In the space heating and standby water heating mode of FIG. 38, each of the first and second solenoid valves 3804, 3806 are energized to allow the working fluid to flow through the loop 3805 as described above for FIGS. 35-37, and the third solenoid valve 3808 is de-energized or off to prevent flow of the working fluid through the bypass line 3508. The controller 64 operates the water heater 14 in conjunction with the space heating mode of the heat pump 3802, as described above for the system 3500, in the standby water heating mode, the groundwater heating mode, or no water heating (in which the system 3800 provides space cooling only). The system 3800 is also operable in a dedicated water heating mode, similar to the dedicated water heating mode of FIG. 36, a thermosiphon space heating mode, similar to the thermosiphon space heating mode of FIG. 37, and a space heating and hydronic heating mode.

[0172] In the thermosiphon space heating mode of the system 3800, the third solenoid valve 3808 is energized to allow the working fluid to flow through the bypass line 3508 between the lines 3204 and 3210. The first and second solenoid valves 3804, 3806 are de-energized (off or closed) to restrict flow of the working fluid in the lines 3204, 3210 to within the portion between the indoor heat exchanger 68 and the valves 3804, 3806, and isolate the line 3206, the expansion device 20, the compressor 72, and the outdoor heat exchanger 70. The compressor 72 and the outdoor fan 78 are turned off in the thermosiphon space heating operating mode. The indoor fan 76 is operated to force the inlet air stream 80 across the indoor coils of the indoor heat exchanger 68, which heats the inlet air stream 80. The solenoid valves 3804, 3806, 3808 are operated to direct the working fluid through the loop 3805 as described above with reference to FIG. 37. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 3105 by natural convection. The water heater 14 is operated in a similar manner as described above for the thermosiphon or compressor-free mode of FIG. 37.

[0173] Description of the controller 64 above with reference to the system 3500 applies to the controller 64 of the system 3800 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3800 using similar control algorithms as used to control the system 3500, which may be modified as appropriate to control the solenoid valves 3804, 3806, 3808 in a similar manner as the three-way valves 3504, 3506.

[0174] In the example systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800 described above, the water heater 14, including the WRHX 36, is positioned entirely indoors. FIGS. 39 and 40 depict a thirteenth example of an integrated heat pump-water heater system 3900 that includes a heat pump 3902 operable in multiple operating modes and a water heater 3930 integrated with the heat pump 3902. The heat pump 3902 includes similar elements and components as the heat pumps described above for the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800, with like elements and components indicated using like reference numerals. The water heater 3930 includes similar elements and components as the water heater 14 described above for the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, and 3800, with like elements and components indicated using like reference numerals.

[0175] The water heater 3930 includes a water heater skid 3932 that includes a water loop 3934 and the WRHX 36 positioned on the water loop 3934. In this example, the WRHX 36 is positioned outdoors to enable additional functionality described below. The lines 48, 50 of the water loop 3932 each extend through the partition 11. The remaining components of the water loop 3932, including the lines 28, 38, 40, and 46, the three-way valves 42, 44, 62, the check valves 54, the water pump 56, and the water tank 26 are each located indoors in the water heater skid 3932. The water heater 3930 also includes a sensor 3936 (e.g., a temperature sensor) positioned outdoors on the line 50 to measure a condition (e.g., temperature) of the water exiting the WRHX 36. Additionally, or alternatively, the sensor 3936 is positioned indoors on the line 50.

[0176] The heat pump 3902 includes a first reversing valve 3920 connected to the compressor 72 by a discharge line 3910, and a second reversing valve 3922 connected to the first reversing valve 3920 by a line 3906. The first reversing valve 3920 is connected to the WRHX 36 by a line 3916 and a line 3918. The second reversing valve 3922 is connected to the outdoor heat exchanger 70 by a line 3912 and the indoor heat exchanger 68 by a line 3904. A line 3908 connects the indoor heat exchanger 68 and the outdoor heat exchanger 70. The expansion device 20 is positioned on the line 3908.

[0177] The first reversing valve 3920 is operable (positionable) between a first position (FIG. 39) in which the WRHX 36 is connected via the lines 3916, 3918 to a working fluid loop 3905 and, specifically, the lines 3910, 3906, respectively, and a second position (FIG. 40) in which the WRHX 36 and the lines 3916, 3918 are isolated from the working fluid loop 3905. The first reversing valve 3920 is thus operable (positionable) to selectively connect the WRHX 36 to the working fluid loop 3905 and isolate the WRHX 36 from the working fluid loop 3905. Because the WRHX 36 is positioned outdoors in this example, even when the WRHX 36 is isolated from the working fluid loop 3905, the WRHX 36 can heat the water in the water loop 3934 by absorbing heat from the ambient environment (e.g., from humid outside air). For example, the WRHX 36 can operate as a condenser for the refrigerant in lines 3916 and 3918. The absorbed heat from the refrigerant in lines 3916 and 3918 to heat the water in lines 48 and 50.

[0178] The second reversing valve 3922 is operable (positionable) between a first position (FIGS. 39 and 40) and a second position (not shown) to reverse the flow direction of the working fluid in the loop 3905. The second reversing valve 3922 enables the heat pump 3902 to operate in a space heating mode (when the second reversing valve 3922 is in the first position) and a space cooling mode (when the second reversing valve 3922 is in the second position). In the first position, as shown in FIGS. 39 and 40, the second reversing valve 3922 directs the working fluid to flow, generally, from the compressor 72 via the lines 3910, 3906, into the line 3904 towards and through the indoor heat exchanger 68, into the line 3908 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. In the second position, the second reversing valve 3922 directs the working fluid to flow, generally, from the compressor 72 via the lines 3910, 3906, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72.

[0179] When the WRHX 36 is connected to the water loop 3905 via the first reversing valve 3920 in the first position, the water in the water loop 3934 can be heated in both the space heating mode and the space cooling mode of the heat pump 3902. In particular, the first reversing valve 3920 in the first position connects the discharge line 3910 to the line 3916, and the line 3918 to the line 3906 between the first reversing valve 3920 and the second reversing valve 3922. As such, in both the space heating mode and the space cooling mode, and irrespective of the position of second reversing valve 3922, the first reversing valve 3920 in the first position directs hot, compressed working fluid through the WRHX 36 to heat the water in the water loop 3934. To cycle water through the water loop 3934, continuously or periodically, the water heater 3930 is controlled by the controller 64 as described above.

[0180] Referring to FIG. 39, in a space heating and water heating mode of the system 3900, each of the first reversing valve 3920 and the second reversing valve 3922 are in the first position. As such, the working fluid flows through the working fluid loop 3905 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3904 towards and through the indoor heat exchanger 68, into the line 3908 towards and successively through the expansion device 20 and the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The indoor heat exchanger 68 operates as the condenser of the heat pump 3902 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82.

[0181] In a space cooling and water heating mode of the system 3900, the first reversing valve 3920 is in the first position and the second reversing valve 3922 is in the second position. As such, the working fluid flows through the working fluid loop 3905 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream80. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed.

[0182] In both the space heating mode (FIG. 39) and the space cooling mode of the heat pump 3902, the water heater 3930 can be controlled to continuously or periodically cycle water through the water loop 3934 for heating the water via the WRHX 36. For example, in response to a determined need for water heating in the water heater 3930, the controller 64 can initiate tank or standby water heating by controlling the water pump 56 to circulate water from the tank 26 through the water loop 3934 and the WRHX 36 and position the three-way valves 42, 44 to allow the water to flow through the loop 3934 between the outlet 27 and the inlet 52 of the tank 26. Additionally, or alternatively, the controller 64 initiates groundwater heating by controlling the three-way valves 62, 44 to allow water to flow from the water supply 58 and through the cold water supply line 46, the water loop 3934, and the WRHX 36. The water heater 14 can additionally or alternatively be controlled for hydronic (water-to-working fluid) heating to supplement the heat pump 3902 in the space heating / cooling mode via the WRHX 36 when conditions in the water heater 14 allow and conditions in the heat pump 3902 demand, as described above.

[0183] The need for hot water and / or supplemental heating in the water heater 3930 can be determined as described above. For example, this can be determined by monitoring the temperature of the water exiting the tank 26 via the sensor 132, monitoring the temperature and / or the level of the water in the tank 26 via the sensor 134, or another suitable operating condition of the water heater 3930. Additionally, or alternatively, the temperature of the water exiting the WRHX 36 is monitored via the sensor 3936 to determine a need for hot water and / or supplemental heating.

[0184] FIG. 40 depicts the system 3900 in an independent space heating and water heating mode. In this mode, the first reversing valve 3920 is in the second position, isolating the WRHX 36 from the loop 3902. The second reversing valve 3922 is in the first position, directing the working fluid to flow through the working fluid loop 3905 as described above for FIG. 39, except that the working fluid flows from the discharge line 3910, through the first reversing valve 3920 and into the line 3906, bypassing the lines 3916, 3918 and the WRHX 36. The system 3900 can also be operated in an independent space cooling and water heating mode. In this mode, the first reversing valve 3920 is in the second position, isolating the WRHX 36 from the loop 3902, and the second reversing valve 3922 is in the second position, directing the working fluid to flow through the working fluid loop 3905 as described above for the space cooling and water heating mode, except that the working fluid flows from the discharge line 3910, through the first reversing valve 3920 and into the line 3906, bypassing the lines 3916, 3918 and the WRHX 36.

[0185] The system 3900 may be operated in the independent space heating and water heating mode (FIG. 40) or the independent space cooling and water heating mode when outside conditions allow (e.g., when outside conditions are suitable for the WRHX 36 to absorb heat from the outside air). The water heater 3930 can be operated to continuously or periodically water through the water loop 3934 and the isolated WRHX 36, and the WRHX 36 can operate to absorb heat from the outside environment to heat the water (e.g., from moisture in the outside air that condenses on the WRHX 36). The controller 64 can also monitor the temperature of the water exiting the WRHX 36 and, if the controller 64 determines that there is a need for water heating that is not adequately being fulfilled in the independent water heating mode, the controller 64 initiates the space heating and water heating mode of FIG. 39 (or the space cooling and water heating mode), such that the working fluid is used to heat the water. The controller 64 can also determine that the working fluid is available to heat the water as described above before initiating the space heating / cooling and water heating mode (e.g., by determining that additional heating is not needed by the heat pump 3902), to balance the ability of the heat pump 3902 to fulfill its requirements and the ability of the water heater 3930 to fulfill its requirements.

[0186] The system 3900 is operable in other operating modes than those shown in FIGS. 39 and 40 and described above. For example, the system 3900 is operable in a dedicated water heating mode, in which the first and second reversing valves 3920, 3922 are each in the first position, the indoor fan 76 is turned off, and the outdoor heat exchanger 70 operates as the evaporator. The system 3900 is also operable in a space heating only mode or a space cooling only mode, in which the heat pump 3902 conditions the inlet air stream 80 as described above while the water heater 3930 is idle (e.g., little to no water flows through the water loop 34), the first reversing valve 3920 is in the second position to isolate the WRHX 36 from the working fluid loop 3905, and the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling). The system 3900 is also operable in a defrost mode, in which the first reversing valve 3920 is in the first position, the second reversing valve 3922 is in the second position, the indoor fan 76 is turned off, the outdoor heat exchanger 70 operates as the condenser (rejecting heat to defrost the outdoor coils), and the expansion device 20 is fully opened and / or bypassed. In the defrost mode of the system 3900, when conditions in the water heater 3930 allow, the water in the water loop 3934 is used to heat the working fluid upstream from the outdoor heat exchanger 70.

[0187] Description of the controller 64 above applies to the controller 64 of the system 3900 unless expressly stated otherwise or the context clearly indicates otherwise. The controller 64 can control operation of the system 3900 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to control the first reversing valve 3920 and the second reversing valve 3922.

[0188] FIGS. 41 and 42 depict a fourteenth example of an integrated heat pump-water heater system 4100 that includes a heat pump 4102 operable in multiple operating modes and the water heater 3930 integrated with the heat pump 4102. The heat pump 4102 includes similar elements and components as the heat pump 3902 of FIGS. 39 and 40, with like elements and components indicated using like reference numerals. The water heater 3930 in this example includes the elements and components of the water heater 3930 as described above for FIGS. 39 and 40, including the WRHX 36 positioned outdoors. The system 4100 is operable in the operating modes described above for the system 3900.

[0189] In this example, in addition to the elements and components of the system 3900 of FIGS. 39 and 40, the system 4100 includes a third reversing valve 4108 connected between the first reversing valve 3920 and the WRHX 36, and between the indoor heat exchanger 68 and the outdoor heat exchanger 70. The third reversing valve 4108 provides additional functionality to the integrated system 4100 relative to the system 3900 of FIGS. 39 and 40. The third reversing valve 4108 is connected to the first reversing valve 3920 by a line 4106, the WRHX 36 by the line 3916, the indoor heat exchanger 68 by a line 4104, and the outdoor heat exchanger 70 by the line 3908. The expansion device 20 is positioned on the line 4104 between the indoor heat exchanger 68 and the third reversing valve 4108.

[0190] FIG. 41 depicts the system 4100 in a space heating and water heating mode, in which the first reversing valve 3920 and the second reversing valve 3922 are in the first position as described above for FIG. 39. The third reversing valve 4108 is also in a first position, which allows the working fluid to flow through a working fluid loop 4105 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 4106 towards and through the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3904 towards and through the indoor heat exchanger 68, into the line 4104 towards and successively through the expansion device 20 and the third reversing valve 4108, into the line 3908 towards and through the outdoor heat exchanger 70, into the line 3912 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The indoor heat exchanger 68 operates as the condenser of the heat pump 4102 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid rejects heat into the inlet air stream 80. The outdoor heat exchanger 70 operates as the evaporator of the heat pump 4102 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid absorbs heat from the outlet air stream 82.

[0191] In a space cooling and water heating mode of the system 4100, the first reversing valve 3920 and the third reversing valve 4108 are each in the first position and the second reversing valve 3922 is in the second position. As such, the working fluid flows through the working fluid loop 4105 such that the working fluid exiting the compressor 72 flows in the line 3910 towards and through the first reversing valve 3920, into the line 4106 towards and through the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, into the line 3912 towards and through the outdoor heat exchanger 70, into the line 3908 towards and through the third reversing valve 4108, into the line 4104 towards and successively through the expansion device 20 and the indoor heat exchanger 68, into the line 3904 towards and through the second reversing valve 3922, and into the line 3914 back towards the compressor 72. The outdoor heat exchanger 70 operates as the condenser of the heat pump 3902 and the outdoor fan 78 forces the outlet air stream 82 across the outdoor coils such that the working fluid rejects heat into the outlet air stream 82. The indoor heat exchanger 68 operates as the evaporator of the heat pump 2402 and the indoor fan 76 forces the inlet air stream 80 across the indoor coils such that the working fluid absorbs heat from the inlet air stream 80. As described above, in the space cooling mode, the outdoor heat exchanger 70 can be cycled, idle (e.g., with the fan 78 turned off) and / or bypassed.

[0192] In both the space heating mode (FIG. 41) and the space cooling mode of the heat pump 3902, the water heater 3930 can be controlled to continuously or periodically cycle water through the water loop 3934 for heating the water via the WRHX 36, as described above. The need for hot water and / or supplemental heating in the water heater 3930 can be determined as described above.

[0193] The system 4100 is operable in other operating modes including those described above for the system 3900 of FIGS. 39 and 40. For example, the system 4100 is operable in an independent space heating and water heating mode or an independent space cooling and water heating mode when outside conditions allow (e.g., when outside conditions are suitable for the WRHX 36 to absorb heat from the outside air). In the independent space heating / cooling and water heating mode of the system, the first reversing valve 3920 is in the second position (see FIG. 40), which bypasses the lines 4106, 3916, and 3918 and isolates the WRHX 36, the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling), and the third reversing valve 4108 is in the first position. The system 4100 is also operable in a dedicated water heating mode, in which the first, second, and third reversing valves 3920, 3922, 4108 are each in the first position, the indoor fan 76 is turned off, and the outdoor heat exchanger 70 operates as the evaporator. The system 4100 is also operable in a space heating only mode or a space cooling only mode, in which the heat pump 4102 conditions the inlet air stream 80 as described above while the water heater 3930 is idle (e.g., little to no water flows through the water loop 34), the first reversing valve 3920 is in the second position to isolate the WRHX 36 from the working fluid loop 3905, the second reversing valve 3922 is positionable between the first position (for space heating) and the second position (for space cooling), and the third reversing valve 4108 is in the first position. The system 4100 is also operable in a defrost mode, in which the first and third reversing valves 3920, 4108 are in the first position, the second reversing valve 3922 is in the second position, the indoor fan 76 is turned off, the outdoor heat exchanger 70 operates as the condenser (rejecting heat to defrost the outdoor coils), and the expansion device 20 is fully opened and / or bypassed. In the defrost mode of the system 4100, when conditions in the water heater 3930 allow, the water in the water loop 3934 is used to heat the working fluid upstream from the outdoor heat exchanger 70.

[0194] Description of the controller 64 above and the functions executed by the controller 64 for the operating modes of the system 3900 applies to the controller 64 of the system 4100. The controller 64 can control operation of the system 4100 using the control algorithms shown in FIGS. 5-8 and described above, which may be modified as appropriate to control the first reversing valve 3920, the second reversing valve 3922, and the third reversing valve 4108.

[0195] FIG. 42 depicts the system 4100 in a hydronic thermosiphon space heating mode, or a “compressor-free” space heating mode, that is enabled using the third reversing valve 4108. In the thermosiphon space heating mode of the system 4100, the compressor 72 and the outdoor fan 78 are idle. The first and second reversing valves 3920, 3922 are in the first position and the third reversing valve 4108 is in a second position. The second position of the third reversing valve 4108 causes the working fluid to bypass three-way valves 3504, 3506 are operated (positioned) to bypass the outdoor heat exchanger 70 and the compressor 72, and flow between the indoor heat exchanger 68 and the WRHX 36. To enable a thermosiphon or compressor-free mode of the heat pump 4102, the indoor heat exchanger 68 is elevated relative to the WRHX 36, and gravity and a difference in temperature and pressure of the working fluid in the indoor heat exchanger 68 and the WRHX 36 promotes circulation through the loop 4105 using natural convection rather than by mechanical force. The system 4105 can be operated in the thermosiphon or compressor-free mode when conditions of the water heater 14 allow using water in the loop 34 for heating the working fluid (e.g., when the temperature of the water exiting the WRHX 36, the temperature of the water exiting the tank 26, the temperature of the water in the tank 26, the level of the water in the tank 26, or another suitable operating condition of the water heater 14 meets a predefined criterion and signals that there is hot water available for heating the working fluid).

[0196] As shown in FIG. 42, in the thermosiphon or compressor-free mode, the reversing valves 3920, 3922, 4108 direct the working fluid through the loop 4105 as follows: working fluid flows through the line 3904 towards and through the indoor heat exchanger 68, into the line 4104 towards and successively through the expansion device 20 (which may be fully opened and / or bypassed) and the third reversing valve 4108, into the line 3916 towards and through the WRHX 36, into the line 3918 towards and through the first reversing valve 3920, into the line 3906 towards and through the second reversing valve 3922, and back into the line 3904. The working fluid is heated in the WRHX 36, raising the temperature and / or pressure of the working fluid, and is cooled in the indoor heat exchanger 68, lowering the temperature and / or pressure of the working fluid. The temperature and / or pressure differential of the working fluid at the WRHX 36 stage and the indoor heat exchanger 68 stage, in conjunction with the difference in elevation between the indoor heat exchanger 68 and the WRHX 36, drives the working fluid through the loop 4105 by natural convection.

[0197] The water heater 3930 is operated in the thermosiphon or compressor-free mode of FIG. 42 as described above to circulate hot water in the loop 3934 between the outlet 27 of the tank 26 and the inlet 52 of the tank 26 using the water pump 56. In this mode, the three-way valve 62 and / or the three-way valve 44 is positioned to restrict water from the water supply 58, which is at a lower temperature relative to the water in the tank 26, from flowing into the loop 3934 and prevent lowering the temperature of the water in the loop 3934.

[0198] The controller 64 also determines whether to operate the system 4100 in the thermosiphon space heating mode of FIG. 42 based on the outside conditions and whether hot water is available in the water heater 3930 for heating the working fluid in the loop 4105 as described above. For example, this can be determined as described above with reference to FIG. 13 and the operations 1304 and 1322. When the controller 64 determines (e.g., at 1304 of FIG. 13) that an outside condition meets or exceeds the predefined criterion (e.g., the ambient temperature is greater than 45° F.), and that there is hot water in the water heater 3930 for the thermosiphon space heating mode of FIG. 42 (e.g., at 1322 of FIG. 13), then the controller 64 controls the system 4100 to initiate the thermosiphon space heating mode. When the controller 64 determines (e.g., at 1304 of FIG. 13) that the outside condition does not meet or exceed the predefined criterion (e.g., the ambient temperature is lower than 45° F.), and / or that there is not hot water in the water heater 3930 for the thermosiphon space heating mode of FIG. 42 (e.g., at 1322 of FIG. 13), then the controller 64 initiates the space heating mode of the heat pump 4102 using the outdoor heat exchanger 70 as the evaporator (e.g., as shown in FIG. 41).

[0199] Table 2 below provides a summary of the operating modes (including heat pump mode and water heating mode) in which the systems 100, 900, 1400, 1600, 2000, 2300, 2400, 2700, 3100, 3200, 3500, 3800, 3900, and 4100 can be operated.TABLE 2Operating mode summary of example integrated heat pump-water heater systemsSpaceSpaceDefrostHeating +DedicatedCooling +modeWaterWaterWaterusingHeatingHeatingHeatingHydronicheatSpaceSpace(Groundwater(Groundwater(GroundwaterThermosiphonfromCoolingHeatingand / orand / orand / orSpacewaterSystemOnlyOnlyStandby)Standby)Standby)HeatingheaterSystemYesYesYesYesYesNoYes100(FIGS.2-4)SystemYesYesYesYesYesYesYes900(FIGS.9-12)SystemYesYesYesYesYesYesYes1400(FIGS.14 and15)SystemYesYesYesYesNoNoYes1600(FIGS.16-19)SystemYesYesYesYesNoYesYes2000(FIGS.20-22)SystemYesYesYesYesNoYesYes2300(FIG.23)SystemYesNoNoNoYesNoNo2400(FIGS.24-26)SystemYesNoNoNoYesYesNo2700(FIGS.27-30)SystemYesNoNoNoYesYesNo3100(FIG.31)SystemNoYesYesYesNoNoNo3200(FIGS.32-34)SystemNoYesYesYesNoYesNo3500(FIGS.35-37)SystemNoYesYesYesNoYesNo3800(FIG.38)SystemYesYesYesYesYesNoYes3900(FIGS.39 and40)SystemYesYesYesYesYesYesYes4100(FIGS.41 and42)

[0200] Referring to FIG. 43 and in view of the integrated heat pump-water heater systems described above, a method 4300 of operating an integrated heat pump-water heater system for an indoor space is described. The system may generally include a heat pump having a refrigerant loop (e.g., suitable piping or lines connecting indoor and outdoor sections), a compressor (which may be a scroll, reciprocating, or rotary type), an indoor air-refrigerant heat exchanger (ARHX) sometimes referred to as an indoor heat exchanger, an outdoor ARHX sometimes referred to as an outdoor heat exchanger, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In certain examples, fans or blowers are provided to force air across the indoor and / or outdoor ARHX. A network of valves, such as a reversing valve connected to the compressor discharge line and one or more additional flow-control or three-way valves, may redirect the refrigerant among the indoor ARHX, the outdoor ARHX, and the WRHX to accommodate multiple operating modes (for example, space heating, space cooling, defrost, or dedicated water heating).

[0201] Method 4300 includes circulating 4305 a refrigerant through the refrigerant loop of the heat pump. The refrigerant may be routed in conduits between the indoor ARHX and outdoor ARHX. A controller can selectively energize a blower or fan to move an air stream across one or both ARHX coils while also controlling refrigerant flow continuously or intermittently, depending on temperature demands or water-heating demands.

[0202] The refrigerant is compressed 4310 by a compressor positioned in the refrigerant loop, raising it to a relatively hot, high-pressure state suitable for releasing heat in subsequent steps. In some systems, an accumulator may be placed upstream of the compressor to manage liquid refrigerant carryover, and the compressor discharge line may feed into a reversing valve (sometimes referred to as a four-way valve).

[0203] Method 4300 provides for positioning 4315 a reversing valve on the refrigerant loop, connected to the compressor discharge or suction line, so that refrigerant flow is directed between the indoor ARHX and the outdoor ARHX based on a selected operating mode (e.g., space heating, space cooling, or defrost). In some configurations, the reversing valve feeds hot, compressed refrigerant either to the indoor coil (for heating) or to the outdoor coil (for cooling), while also returning lower-pressure vapor to the compressor's suction side.

[0204] The refrigerant passes through an indoor ARHX where heat is exchanged 43220 with an indoor air stream. During space heating, the indoor ARHX may act as a condenser, releasing heat to the indoor air. Conversely, when the system is in space cooling mode, the indoor ARHX acts as an evaporator, absorbing heat from the indoor air stream.

[0205] Heat is exchanged 4325 between the refrigerant and the outdoor air via an outdoor ARHX. In space-heating mode, this outdoor ARHX may function as an evaporator, absorbing heat from outside air. In space-cooling mode, it typically operates as a condenser rejecting heat to the outdoor environment. Depending on design, a blower or fan may drive outside air across the outdoor coil to promote efficient heat exchange.

[0206] Water is circulated 4330 in a water loop of the water heater using a water pump. For example, water may be drawn from a hot water tank outlet or, in some modes, from a cold water supply line. A series of check valves and three-way valves can be actuated to direct water through the loop in different ways (e.g., for tank heating, groundwater heating, or hydronic support).

[0207] The WRHX is used to exchange 4335 heat between the refrigerant and the water loop. Depending on system conditions, the WRHX heats water by thermally connecting to the hot, compressed refrigerant flow (for example, downstream of the compressor and before or after the indoor ARHX). Under some circumstances, the WRHX can instead deliver heat from the water to the refrigerant sometimes referred to as “hydronic heating. For example, the water may heat the refrigerant if the tank water is at a suitably high temperature and the system determines supplemental heating of the refrigerant loop.

[0208] The system positions 4340 a network of valves (for example, reversing valves or three-way valves) on the refrigerant loop to communicate with both the reversing valve and the ARHX coils. Additional solenoid valves, bypass valves, or dedicated three-way valves may selectively bypass certain coils or reroute refrigerant into the WRHX to make water heating available in different operating modes.

[0209] The network of valves is controlled to direct 4345 refrigerant flow through the WRHX so that water heating is available even during modes such as space cooling. For instance, compressed refrigerant exiting the compressor can be routed through the WRHX first, then to the outdoor ARHX (when it is acting as a condenser), thereby allowing waste heat to be captured and sent to the water loop.

[0210] At least one operating mode may isolate 4350 the compressor and the outdoor ARHX from refrigerant flow, routing refrigerant between the WRHX and the indoor ARHX only. In such embodiments, gravity-driven natural convection can circulate refrigerant without energizing the compressor, also referred to as a hydronic “thermosiphon.” This thermosiphon mode may heat the indoor air by transferring heat from relatively hot tank water to the refrigerant, then to the indoor ARHX, which can operate as a condenser coil if the fan is running.

[0211] One or more of these steps may be performed concurrently or in a different sequence. Additional sub-steps, such as cycling an outdoor fan off to preserve refrigerant temperature for water heating, may be implemented based on monitored conditions (e.g., ambient temperature, tank temperature, or user preferences). A controller typically coordinates valve positions, pump operation, and compressor usage to balance comfort and hot-water requirements.

[0212] Accordingly, the foregoing method 4300 enables integrated operation of the heat pump and water heater across multiple modes while preserving flexibility in overall layout and component selection. Additional features, examples, and variations may be implemented consistent with the broader system descriptions above, such as the inclusion of expansion devices (e.g., thermal expansion valves or fixed orifices), suction-line accumulators, and other standard vapor-compression components.

[0213] Referring to FIG. 44 and in view of the integrated heat pump-water heater systems described above, a method 4400 of operating an integrated heat pump-water heater system for an indoor space is described. The system includes a heat pump having a refrigerant loop (e.g., suitable piping or lines connecting indoor and outdoor sections), a compressor (e.g. a scroll compressor, a reciprocating compressor, or a rotary compressor), an indoor air-refrigerant heat exchanger (ARHX) to exchange heat with an indoor air stream, an outdoor ARHX to exchange heat with outdoor air, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In the example embodiment, the indoor ARHX and outdoor ARHX each include heat exchange coils and at least one fan or blower to move air across those coils. A network of valves, such as one or more reversing valves connected to the compressor's discharge or suction lines and additional three-way or flow-control valves, may reroute refrigerant among the indoor ARHX, outdoor ARHX, and WRHX to accommodate the mode of operation space heating, space cooling, defrost, or dedicated water-heating modes.

[0214] Refrigerant is circulated 4405 through the heat pump's closed-loop circuit. This controller is programmed to determine refrigerant circulation based on indoor temperature requirements or hot-water demand. As the refrigerant flows between indoor and outdoor sections, fans can be selectively energized to transfer air over the ARHX coils.

[0215] The refrigerant is compressed 4410 by a compressor connected to the refrigerant loop to raise its pressure and temperature. The compressed refrigerant is directed toward either the indoor ARHX or outdoor ARHX, depending on whether the system is operating in a space heating mode or a space cooling mode. A first reversing valve is selectively positioned 4415 on the refrigerant loop connected to the compressor so that the WRHX is either connected to, or isolated from, the refrigerant flow of the refrigerant loop. When the first reversing valve is positioned in the first position and the compressed refrigerant is directed through the WRHX to heat water in the system's water loop. When the reversing valve is positioned in the second position, the valve can bypass the WRHX, preserving higher efficiency for standard space conditioning. A second reversing valve is positioned 4420 to route refrigerant flow between the indoor and outdoor heat exchangers based on the operating mode. By controlling the configuration of the valves the system can determine which coil (indoor or outdoor) receives the compressed refrigerant and which coil handles the lower-pressure vapor returning to the compressor.

[0216] The heat from the compressed refrigerant is exchanged 4425 with the indoor air via the indoor ARHX. In the heating mode, the compressed refrigerant from the compressor is sent to the ARHX to release the heat into the indoor air stream, warming the space. Conversely, when the system is operating in the cooling mode, the indoor ARHX acts as an evaporator, absorbing heat from the indoor air. In some embodiments a fan or blower forces air across the coil for increased heat transfer. The heat from the outdoor ARHX is exchanged 4430 with the outdoor air. In the heating mode, the refrigerant may enter the outdoor coil as a low-temperature vapor, absorbing heat from outside air. In the cooling mode, the ARHX operates as a condenser, rejecting heat to the outdoor environment. The outdoor fan can be cycled on or off depending on ambient conditions, water heating demands, or efficiency considerations.

[0217] The WRHX exchanges 4435 heat with a water loop. The water loop includes a hot water tank, a pump, and various check and three-way valves for routing water from either the tank outlet or a cold supply line. Circulating water through the WRHX captures heat from the refrigerant loop in the heating mode. The WRHX may capture heat from the refrigerant loop in the cooling mode if the compressed refrigerant is sufficiently hot. The resulting heated water is then delivered back to the hot water tank or used directly. The system may run a dedicated water-heating mode by partially or fully bypassing normal space conditioning so that the WRHX becomes the primary condenser. Conversely, if tank water is sufficiently hot, the WRHX can deliver heat to the refrigerant in a “hydronic heating” scenario, for example helping defrost or supporting mild indoor heating through a thermosiphon arrangement (where gravity and temperature differentials drive natural refrigerant circulation, reducing or eliminating compressor usage).

[0218] Each of these steps 4405-4435 may be performed in series, concurrently, or in a modified order, depending on operational demands and configuration. The controller typically manages valve positions, blower or fan operation, compressor staging, and water circulation based on measured temperatures, pressures, and setpoints. The flexibility of the system provides indoor climate control and water heating simultaneously or independently, while also accommodating defrost modes or thermosiphon modes of operation. In this way, the method 4400 enables integrated operation of the heat pump and water heater across multiple modes in a cost-effective, energy-efficient manner, without sacrificing the adaptability needed for diverse climate conditions or occupant preferences.

[0219] Referring to FIG. 45, a representative flow diagram illustrates a method 4500 of operating an integrated heat pump-water heater system that provides both space conditioning and water heating. The system includes a heat pump with a refrigerant loop (for example, piping or conduits connecting indoor and outdoor sections), a compressor, an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, and a water-refrigerant heat exchanger (WRHX) thermally coupling the refrigerant loop to a water heater. A controller regulates valve positions, fan operations, and pump speeds based on ambient conditions, desired indoor temperature, or hot-water demands.

[0220] The method 4500 includes circulating 4505 refrigerant through the heat pump's refrigerant loop. The compressed, high-pressure refrigerant is directed toward a reversing valve and a network of valves, which together route the refrigerant among the indoor ARHX, the outdoor ARHX, and the WRHX.

[0221] When operating in the space heating mode 4510, the reversing valve is positioned 4515 so that hot, high-pressure refrigerant from the compressor is directed toward the indoor ARHX (which acts as a condenser) and returned from the outdoor ARHX as an evaporator. The network of valves are positioned 4520 to direct the high-pressure refrigerant from the reversing valve towards the WRHX. This may occur before or after the indoor ARHX, depending on valve arrangement. Refrigerant flowing through the WRHX transfers 4525 thermal energy to water circulating in the water loop of the water heater. A water pump draws water from a storage tank (or a cold supply line) through check valves and three-way valves, delivering it into the WRHX to absorb heat from the refrigerant. After leaving the WRHX, the refrigerant proceeds to the indoor ARHX, rejecting heat 4530 into the indoor air stream and thus warming the occupied space. The now-cooled refrigerant then travels through the outdoor ARHX, absorbing heat 4535 from outside air, and cycles back to the compressor.

[0222] When operating in the space cooling mode 4540, the reversing valve is positioned 4545 to direct the hot, high-pressure refrigerant toward the outdoor ARHX as a condenser, rejecting heat to the outside air. The refrigerant then flows into the network of valves positioned 4550 so that the refrigerant also passes through the WRHX. Heat from the refrigerant is transferred 4555 to the water circulating in the water loop and capturing unused heat. From the WRHX, the refrigerant is directed to the indoor ARHX as an evaporator. The heat from the indoor air steam is absorbed 4560 by the indoor ARHX to cool the indoor space and lower the indoor temperature. The refrigerant then returns to the ARHX to reject heat 4565 from the refrigerant to the outdoor air steam and returns to the compressor to complete the cycle.

[0223] In the space heating mode and / or the space cooling mode, the controller may enable or bypass heat transfer in the WRHX. For example, if the water tank is already at its setpoint temperature, the system may route refrigerant around the WRHX. The refrigerant loop may be directed through the WRHX to preheat water if there is a demand for hot water. By recovering thermal energy in both operating modes, the system enhances energy efficiency 4570 by utilizing the refrigerant to heat the water across the space heating mode and the space cooling mode. In the example embodiment, the water heater's pump and valves can be adjusted for tank heating, groundwater heating, or optional hydronic support (where hot tank water supplements heat for the refrigerant loop under certain conditions).

[0224] In some implementations, the system may include a dedicated defrost cycle, where the reversing valve temporarily directs hot refrigerant to the outdoor coil to melt accumulated frost. Under moderate outdoor temperatures, the controller may stage or cycle outdoor fans so the refrigerant remains sufficiently hot for water heating. The system may operate in a thermosiphon or compressor-free mode, where the compressor and outdoor ARHX are isolated, and naturally circulating refrigerant (driven by gravity and temperature differentials) transfers heat between the WRHX and the indoor ARHX to heat the indoor air using stored hot water without running the compressor.

[0225] One or more of these steps can occur at the same time or in a modified sequence. Additional sub-steps such as intermittently shutting off the outdoor fan to maintain higher refrigerant temperatures or activating a bypass line may be incorporated to optimize energy usage, meet occupant preferences, or protect system components.

[0226] FIG. 45 illustrates a method 4500 for facilitating an integrated heat pump operation for both space conditioning and water heating. The system directs refrigerant to the WRHX in either the space heating mode or the space cooling mode to repurpose unused thermal energy that would otherwise be lost, resulting in increased overall efficiency and reduced operational costs. The described systems and methods also preserves design flexibility, allowing for different compressor types (e.g., scroll, rotary, or reciprocating), various expansion devices, and optional defrost or thermosiphon capabilities.

[0227] Referring to the flow chat illustrated in FIG. 46 and in view of the integrated heat pump-water heater systems described above, a method 4600 of operating an integrated heat pump-water heater system for an indoor space is described. The system includes a heat pump with a refrigerant loop (for example, tubing or piping between indoor and outdoor sections), a compressor (such as a scroll compressor, reciprocating compressor, or rotary compressor), an indoor air-refrigerant heat exchanger (ARHX), an outdoor ARHX, and a water heater having a water loop thermally coupled via a water-refrigerant heat exchanger (WRHX). In the example embodiment, one or more fans or blowers may be provided to move air across each ARHX. A network of valves, such as a reversing valve connected to the compressor discharge line and additional three-way or flow-control valves, is arranged so that refrigerant is directed between the indoor ARHX, the outdoor ARHX, and the WRHX, depending on the operating mode (e.g., space heating, space cooling, defrost, or dedicated water heating).

[0228] The system circulates 4605 a refrigerant through the refrigerant loop of the heat pump. A controller runs the compressor to drive refrigerant flow between the indoor ARHX and the outdoor ARHX, with air being transferred across these heat exchangers by fans as needed. During the space heating mode, the refrigerant is directed by the valves to condense in the indoor ARHX, delivering heat to the indoor air. Conversely, in the space cooling mode, the refrigerant evaporates in the indoor ARHX, removing heat from the indoor air.

[0229] The refrigerant is compressed by the compressor positioned in the refrigerant loop. The compression raises the refrigerant to a relatively hot, high-pressure state, enabling subsequent heat release in the indoor coil, the outdoor coil, or the WRHX depending on the mode of operation. The system includes a suction line to manage refrigerant in the refrigerant loop. The compressor discharge line is connected to at least one reversing valve for directing compressed refrigerant to a chosen heat exchanger based on the operating mode.

[0230] A reversing valve is positioned 4610 on the refrigerant loop (for instance, in the compressor discharge or suction line) so that refrigerant flow can be toggled between the indoor ARHX and the outdoor ARHX. The reversing valve reroutes the hot, compressed refrigerant in the space heating mode or the space cooling mode, and it may also be switched to a defrost setting where compressed vapor is driven through the outdoor coil to melt frost buildup.

[0231] Water is circulated 4615 in a water loop of the water heater using a mechanical pump. In the example embodiment, the water loop includes a hot water tank, where water can be drawn from an outlet line and then returned to an inlet line after passing through the WRHX. Alternatively, water from a cold supply line may also be connected to the WRHX. Various three-way and check valves can be configured so that water is directed appropriately for heating, hydronic assist, or standby recirculation. The WRHX transfers heat between the refrigerant loop and the water loop. When the hot refrigerant flows through the WRHX, it may release a portion of its thermal energy to the circulating water, raising the water's temperature before that water returns to the storage tank or is delivered for immediate use. In some operating modes (often referred to as hydronic heating modes), hot water from the tank can be used to add heat to the refrigerant.

[0232] A network of valves (in addition to the primary reversing valve) are positioned 4620 on the refrigerant loop to allow or restrict flow into the WRHX in different operating modes. For example, additional three-way or solenoid valves may selectively bypass the WRHX if water heating is not needed or if operating conditions (like outdoor temperatures) are unfavorable. Alternatively, in space cooling mode, compressed refrigerant can be routed through the WRHX to repurpose unused thermal energy from the refrigerant for water heating.

[0233] The controller directs 4625 the refrigerant flow through the WRHX so that water heating can remain active across each of the operating modes. The circulation of the refrigerant through the configuration of valves transfers 4630 heat from the refrigerant to the water using the WRHX. For example, the refrigerant exits the compressor at high temperature, passes through the WRHX to transfer some heat into the water, and then proceeds to the outdoor ARHX to reject any remaining heat. In the example embodiment, a controller automates these steps by monitoring water temperature, indoor thermostat settings, and outdoor conditions.

[0234] In some embodiments, at least one operating mode may isolate the compressor and the outdoor ARHX entirely (e.g., turning them off or bypassing them) such that refrigerant naturally circulates between the WRHX and the indoor ARHX via gravity and a temperature / pressure differential, also referred to as “thermosiphon” mode. During the thermosiphon mode, no mechanical compression is required, and hot water in the WRHX transfers heat to the indoor ARHX when the indoor fan is running. Thermosiphon may be used to provide additional heating or to assist in defrost efforts.

[0235] Any one or more of the steps of method 4600 can be carried out in different orders, or concurrently. Various sub-steps (for example, cycling fans off to preserve refrigerant temperature for water heating, or metering refrigerant via an expansion device) may be employed based on temperature conditions and operational goals. A controller typically coordinates valve positions, compressor operation, and pump flow to balance comfort demands, water heating demands, or energy efficiency. The system can provide indoor space conditioning and heated water simultaneously or individually, depending on the mode of operation and the arrangement of the valves, heat exchangers, and control logic.

[0236] Example systems and methods described relate to integrated heat pump-water heater systems enable greater flexibility and variability to the integration of the heat pump and the water heater, enabling heating of water in the water heater in a greater number of operating modes of the heat pump, enabling heating of working fluid of the heat pump via the water heater, executing various control algorithms that enable improved and well-controlled integration of the heat pump and the water heater, expanding the ability of the heat pump and the water heater to each fulfill their respective demands for the indoor space while providing cost and energy savings via their integration, reducing the cost, complexity, and footprint associated with the integrated heat pump-water heater system, and / or enabling existing heat pump systems (e.g., in residential or commercial buildings) to be retrofitted and integrated with a water heater without costly additional infrastructure upgrades.

[0237] Technical advantages of the present disclosure include, but are not limited to including, i) enabling hot water integration without any additional refrigerant / water lines penetrating a partition or exterior wall of a building house (e.g., the heat pump can remain a 2-pipe system); ii) enabling hot water generation with heat pump system in space cooling mode, space heating mode, or dedicated hot water heating mode; iii) enabling efficient and cost-effective installation of a water heating integration kit under several scenarios, including for new homes and buildings and existing homes and buildings (e.g., in the event of water heater breaks, air conditioning and / or heat pump breaks, or for retrofitting and integrating an existing air conditioner and / or heat pump and water heater); iv) enabling the integration of an air conditioner and / or heat pump with existing hot water heater technology including, but not limited to including, electric resistance water heaters, gas or fossil fuel water heaters, electric heat pumps, dual fuel water heating, and the like, and combinations thereof; v) enables integrated water heating; vi) enabling hydronic heating (providing supplemental heating to the heat pump via hot water); vii) enabling space heating via a thermosiphon (compressor-free operation) to reduce energy utilization; and / or viii) enabling defrost of outdoor coil using hot water as a heat source (including via thermosiphon), thus reducing or eliminating the need for auxiliary refrigerant heating.

[0238] The example systems and methods described can be used in conjunction with any suitable hot water tank, including tanks that utilize an electric resistance heater and / or a gas burner as a heat source for heating water in the tank. Currently, electrification and decarbonization standards and regulations are moving from fossil fuel to electricity in order to reduce greenhouse gas emissions. The majority of single-family residential home installed base are minimum efficiency natural gas (45%) or resistance electric (35%). Future water heater efficiency standards in some states / regions may eliminate all fossil fuel water heaters and minimum efficiency resistance electric, leaving standalone heat pump water heaters as one of the only potential options for providing hot water to the indoor space. The example systems and methods address these problems and provide a reliable, cost-effective, and efficient source of heat for water that can reduce or minimize energy utilization. Additionally, the example systems and methods also enable dual fuel water heating (e.g., using both electrical resistance heating and gas heating) that can balance and minimize the energy utilization of each fuel source.

[0239] Example embodiments of the present disclosure can be implemented, for example, in HVAC systems and related methods. The systems and methods are not limited to the specific embodiments described herein, but rather, components of the system and methods may be used independently and separately from other components described herein. For example, the systems described herein may be used in systems other than HVAC systems, such as swimming pool heating systems or any other suitable system that utilizes hot water.

[0240] When introducing elements of the present disclosure or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,”“including,”“containing” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., “top”, “bottom”, “side”, etc.) is for convenience of description and does not require any particular orientation of the item described.

[0241] As various changes could be made in the above constructions and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawing(s) shall be interpreted as illustrative and not in a limiting sense.

Examples

Embodiment Construction

[0034]FIG. 1 is a schematic of a system 10 that includes a heat pump 12 and a water heating unit 14, or water heater 14. In the example system 10, the heat pump 12 operates according to a vapor-compression cycle and circulates a working fluid (e.g., a refrigerant) in a working fluid loop 15 between an indoor unit 16 and an outdoor unit 18. The indoor unit 16 is positioned in the indoor space and includes an indoor heat exchanger 68 (see, e.g., FIG. 2) that operates to condition an air stream directed to an indoor space (e.g., a building or residence), by exchanging heat between the working fluid and the air stream. The outdoor unit 18 is positioned outside the indoor space (e.g., outside the building or residence) and includes an outdoor heat exchanger 70 (see, e.g., FIG. 2) that operates to exchange heat between the working fluid and the outside air. The indoor heat exchanger 68 is also referred to as an indoor air-refrigerant heat exchanger (ARHX) and outdoor heat exchanger 70 is ...

Claims

1. An integrated heat pump-water heater system, comprising:a heat pump operable in multiple operating modes for conditioning an indoor space, the heat pump comprising a refrigerant loop, and an indoor heat exchanger and an outdoor heat exchanger each on the refrigerant loop;a water heater comprising a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects water in the water loop and refrigerant in the refrigerant loop; anda controller connected to the heat pump and the water heater, wherein, when the heat pump is operating in a space heating mode, the controller is configured to:determine that a condition of the water heater indicates that the water is available for heating the refrigerant, and in response, control supply of the water to the WRHX to heat the refrigerant and control the heat pump to direct the refrigerant through the WRHX;when an ambient condition is met and the condition of the water heater indicates that the water is available for heating the refrigerant, control the heat pump to direct the refrigerant to flow between the WRHX and the indoor heat exchanger and to bypass the outdoor heat exchanger, wherein the refrigerant is heated by the water using the WRHX; andwhen the ambient condition is not met and / or the condition of the water heater indicates that the water is not available for heating the refrigerant, control the heat pump to direct the refrigerant to flow between the indoor heat exchanger and the outdoor heat exchanger, wherein the refrigerant is heated by the outdoor heat exchanger.

2. The system of claim 1, wherein the water heater comprises a temperature sensor on the water loop, and wherein the condition of the water heater that indicates that the water is available for heating the refrigerant is determined based on a temperature of the water measured by the temperature sensor.

3. The system of claim 1, wherein the controller is further configured to determine a need to heat the indoor space and, in response, control the heat pump to operate in the space heating mode.

4. The system of claim 3, wherein the controller is further configured to:determine that there is a need to heat the refrigerant using the WRHX when the heat pump is in the space heating mode; andin response to determining that the condition of the water heater indicates that the water is available for heating the refrigerant, control supply of the water to the WRHX to heat the refrigerant and control the heat pump to direct the refrigerant to flow through the WRHX.

5. The system of claim 4, wherein, in response to determining that the condition of the water heater indicates that the water is not available for heating the refrigerant, the controller is configured to limit the supply of the water to the WRHX.

6. The system of claim 1, wherein the controller is configured to:determine that there is a not a need to heat the refrigerant using the WRHX when the heat pump is in the space heating mode;in response to determining that the condition of the water heater indicates that water heating is needed in the water heater, control the heat pump to heat the refrigerant in the outdoor heat exchanger and direct the refrigerant through the WRHX downstream from the outdoor heat exchanger; andcontrol the water heater to operate in a water heating mode wherein the water is supplied to the WRHX and heated by the WRHX.

7. The system of claim 1, wherein, when the heat pump is operating in a space cooling mode, the controller is further configured to:control the heat pump to heat the refrigerant in the indoor heat exchanger and direct the refrigerant through the WRHX upstream from the indoor heat exchanger; andin response to determining that the condition of the water heater indicates that water heating is needed in the water heater, control the water heater to operate in a water heating mode wherein the water is supplied to the WRHX and heated by the WRHX.

8. The system of claim 7, wherein, in response to determining that the condition of the water heater indicates that the water is not available for heating the refrigerant, the controller is configured to limit the supply of the water to the WRHX.

9. The system of claim 7, wherein, when the heat pump is operating in a space cooling mode and in response to determining that the condition of the water heater indicates that water heating is needed in the water heater, the controller is further configured to cycle and / or turn off an outdoor fan based on a condition of the heat pump indicative of an ability of the working fluid exiting the outdoor heat exchanger to heat the water using the WRHX.

10. The system of claim 9, wherein the condition of the heat pump is a temperature of the working fluid exiting the outdoor heat exchanger.

11. The system of claim 1, when the heat pump is operating in the space heating mode, the controller is configured to:determine a demand for a defrost cycle and, in response, control the heat pump to reject heat from the refrigerant in the outdoor heat exchanger; anddetermine that the condition of the water heater indicates that the water is available for heating the refrigerant in the WRHX, and in response, control supply of the water to the WRHX to heat the refrigerant and control the heat pump to direct the refrigerant through the WRHX upstream from the outdoor heat exchanger.

12. The system of claim 11, wherein, during the defrost cycle, the controller is configured to control the indoor heat exchanger to be idle.

13. The system of claim 1, wherein, when the heat pump is operating in the space heating mode, the ambient condition is met, and the condition of the water heater indicates that the water is available for heating the refrigerant, the controller is further configured to determine that a condition of the heat pump indicates a demand for additional heating of the indoor space, and, in response, control the heat pump to direct the refrigerant to flow between the indoor heat exchanger and the outdoor heat exchanger, wherein the refrigerant is heated by the outdoor heat exchanger.

14. The system of claim 13, wherein, when the heat pump is operating in the space heating mode, the ambient condition is met, the condition of the water heater indicates that the water is available for heating the refrigerant, and the condition of the heat pump indicates a demand for additional heating of the indoor space, the controller is further configured to control the heat pump to direct the refrigerant to flow between the WRHX and the indoor heat exchanger and to bypass the outdoor heat exchanger, wherein the refrigerant is heated by the water using the WRHX upstream from the indoor heat exchanger.

15. An integrated heat pump-water heater system, comprising:a heat pump operable in multiple operating modes for conditioning an indoor space, the heat pump comprising a refrigerant loop, and an indoor heat exchanger and an outdoor heat exchanger each on the refrigerant loop;a water heater comprising a water loop and a water-refrigerant heat exchanger (WRHX) that thermally connects water in the water loop and refrigerant in the refrigerant loop; anda controller connected to the heat pump and the water heater, wherein the controller is configured to:when the heat pump is operating in a space heating mode, control the heat pump to reject heat from the refrigerant in the indoor heat exchanger into an inlet air stream;when the heat pump is operating in a space cooling mode, control the heat pump to absorb heat into the refrigerant in the indoor heat exchanger from the inlet air stream;in each of the space heating mode and the space cooling mode, determine that a condition of the water heater indicates a need for water heating and that a condition of the heat pump indicates an availability of the refrigerant in the refrigerant loop to heat the water in the water loop and, in response, control supply of the water to the WRHX and control the heat pump to direct the refrigerant through the WRHX for heating the water; andin the space heating mode, determine that the condition of the heat pump indicates that the refrigerant in the refrigerant loop is not available to heat the water in the water loop and, in response and irrespective of the need for water heating in the water heater, limit supply of the water to the WRHX.

16. The system of claim 15, wherein the condition of the water heater indicative of the need for water heating is a temperature of the water in the water loop.

17. The system of claim 15, wherein, in the space heating mode, the condition of the heat pump indicative of the availability of the refrigerant in the refrigerant loop to heat the water in the water loop is a temperature of inlet air stream.

18. The system of claim 15, wherein, in the space cooling mode, the controller is further configured to determine that the condition of the heat pump indicates that the refrigerant in the refrigerant loop is not available to heat the water in the water loop and, in response, cycle and / or turn off an outdoor heat fan.

19. The system of claim 15, wherein, in the space cooling mode, the condition of the heat pump indicative of the availability of the refrigerant in the refrigerant loop to heat the water in the water loop is a temperature of the refrigerant exiting the outdoor heat exchanger.

20. A method for operating an integrated heat pump-water heater system to condition an indoor space and heat water, the method comprising:circulating a refrigerant through a refrigerant loop using a heat pump operable in multiple operating modes, wherein the heat pump includes a compressor, an indoor air-refrigerant heat exchanger (ARHX), and an outdoor ARHX each positioned on the refrigerant loop;positioning a reversing valve on the refrigerant loop, the reversing valve being connected to the compressor, to direct a flow of the refrigerant between the indoor ARHX and the outdoor ARHX based on a selected operating mode of the heat pump;circulating water through a water loop of a water heater, wherein the water loop is thermally connected to the refrigerant loop via a water-refrigerant heat exchanger (WRHX);positioning a network of valves on the refrigerant loop, the network of valves being connected to the reversing valve, the indoor ARHX, and the outdoor ARHX;directing, by the network of valves, the flow of the refrigerant through the WRHX in each operating mode of the heat pump; andtransferring heat from the refrigerant to the water via the WRHX to heat the water, wherein the steps of circulating the refrigerant, positioning the reversing valve, circulating the water, positioning the network of valves, directing the flow, and transferring heat are performed in an interconnected sequence to enable simultaneous conditioning of the indoor space and heating of the water across the multiple operating modes.

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