Water heater system and method of operating same

Abstract

There is described a water heater system having: first and second water tanks in fluid communication with a cold water line and a hot water line; a cold water valve in fluid communication between the cold water line and the first water tank; a water heating circuit having a water heater, a first inlet conduit fluidly connecting the first water tank to the water heater, and a first outlet conduit fluidly connecting the water heater to the first water tank; and a controller communicatively coupled to the water heater and the cold water valve, the controller configured for: when the first water tank is fully filled with water from the cold water line, operating the first water tank in a heat charging mode including: while the cold water valve remains closed, circulating said water across the water heating circuit, said circulating including heating the water up to a temperature threshold.

Description

WATER HEATER SYSTEM AND METHOD OF OPERATING SAMEFIELD

[0001] The improvements relate to water heater systems and more particularly relate to water heater systems incorporating more than one water tank.BACKGROUND

[0002] Domestic buildings such as houses generally have their own water heaters to supply hot water demands originating from the hot water tap(s), the shower(s), and / or the dishwasher. Such water heaters are selected based on the estimated hot water consumption of the household. Although existing water heaters were satisfactory to a certain degree, there remains room for improvement.SUMMARY

[0003] Multi-residential buildings are often designed by annexing multiple single-unit residential buildings to one another. It is no surprise that, often times, such multi-residential buildings incorporate a certain number of residential units each having their own dedicated water heater. In such situations, potential scale savings are forfeited as the water heaters are independently owned and operated. Moreover, it was found that the total cost of the multiple individual water heaters can otherwise be invested in a water heater system which would supply hot water across the whole multi-residential building while being more economical in terms of initial and operating costs.

[0004] In an aspect, there is thus proposed a water heater system having a number of water tanks each connected to a common hot water line and to a common cold water line. The water tanks are in fluid communication with one or more water heating circuits which can heat water of one or more of the water tanks simultaneously or sequentially. It was found that heating the entirety of the cold water contained in a single water tank up to a temperature threshold, while isolating it from the hot water line and cold water line, can be more energy efficient, especially in situations where the water heating circuit involves the use of heat pump(s). Accordingly, the water heater system described herein is configured tooperate one of the water tanks in such an isolated, heat charging mode while the other water tanks are operated in a mode of operation which, upon demand, allows hot water to be supplied to the households via the hot water line.

[0005] In accordance with a first aspect of the present disclosure, there is provided a water heater system comprising: first and second water tanks in fluid communication with a cold water line and a hot water line; a first cold water valve in fluid communication between the cold water line and the first water tank; a water heating circuit having a water heater, a first inlet conduit fluidly connecting the first water tank to the water heater, and a first outlet conduit fluidly connecting the water heater to the first water tank; and a controller communicatively coupled to the water heater and the first cold water valve, the controller configured for: when the first water tank is fully filled with water from the cold water line, operating the first water tank in a heat charging mode including: while the first cold water valve remains closed, circulating said water across the water heating circuit, said circulating including heating the water up to a temperature threshold.

[0006] Further in accordance with the first aspect of the present disclosure, said heating can for example be performed in one uninterrupted heating session.

[0007] Still further in accordance with the first aspect of the present disclosure, while the first water tank is operated in the heat charging mode, the second water tank can for example be operated in a normal mode of operation which, upon demand, allows hot water to be supplied via the hot water line.

[0008] Still further in accordance with the first aspect of the present disclosure, the water heater system can for example further comprise a second cold water valve in fluid communication between the cold water line and the second water tank, the water heating circuit having a second inlet conduit and a second outlet conduit fluidly connecting the second water tank and the water heater to one another, the controller further configured for switching the second water tank from a normal mode of operation to a corresponding heat charging mode.

[0009] Still further in accordance with the first aspect of the present disclosure, the water heater system can for example further comprise, upon said switching the second water tank from a normal mode of operation to a corresponding heat charging mode, switching the first water tank from the heat charging mode to a mode of operation which, upon demand, allows water having a temperature above the temperature threshold to be supplied via the hot water line.

[0010] Still further in accordance with the first aspect of the present disclosure, the water heater system can for example further comprise, when the water of the first water tank reaches the threshold temperature, operating the first water tank in a heat maintaining mode including: upon hot water demand, and while the first cold water valve remains closed, dispensing a first quantity of water from the first water tank to the hot water line at a first location thereof and filling the first water tank with a second quantity of water from the hot water line at a second location thereof, the second location upstream from the first location, the first quantity of water corresponding to the second quantity of water.

[0011] Still further in accordance with the first aspect of the present disclosure, the water heater system can for example further comprise, when the water of the first water tank reaches the threshold temperature, operating the first water tank in a heat discharging mode including: upon hot water demand, opening the first cold water valve thereby receiving into the first water tank a first quantity of water from the cold water line and dispensing water from the first water tank to the hot water line.

[0012] Still further in accordance with the first aspect of the present disclosure, the water heater can for example include a heat pump.

[0013] Still further in accordance with the first aspect of the present disclosure, said water filling the first water tank can for example have a temperature below 20°C, preferably below 15°C, and most preferably below 10°C.

[0014] Still further in accordance with the first aspect of the present disclosure, said temperature threshold can for example be at least 40°C, preferably at least 50°C and most preferably at least 60°C.

[0015] Still further in accordance with the first aspect of the present disclosure, the water heating circuit can for example have a circulating pump forcing a flow of water from the first water tank to the water heater via the first inlet conduit and back to the first water tank via the first outlet conduit.

[0016] Still further in accordance with the first aspect of the present disclosure, the water heating circuit can for example be external to the first and second water tanks.

[0017] In accordance with a second aspect of the present disclosure, there is provided a method of operating a water heater system, the water heater system having a plurality of water tanks in fluid communication with a cold water line and a hot water line; a plurality of cold water valves in fluid communication between a corresponding one of the plurality of water tanks and the cold water line; and a water heating circuit having a water heater, inlet conduits fluidly connecting the water tanks to the water heater, and outlet conduits fluidly connecting the water heater to the water tanks, the method comprising: upon determining that a given water tank of the plurality of water tanks is fully filled with water from the cold water line, operating the given water tank in a heat charging mode including: while the corresponding cold water valve remains closed, circulating said water across said water heating circuit, said circulating including heating the water up to a temperature threshold.

[0018] Further in accordance with the second aspect of the present disclosure, said heating can for example be performed in one uninterrupted heating session.

[0019] Still further in accordance with the second aspect of the present disclosure, while the given water tank is operated in the heat charging mode, at least another one of the plurality of water tanks can for example be operated in a normal mode of operation which, upon demand, allows hot water to be supplied via the hot water line.

[0020] Still further in accordance with the second aspect of the present disclosure, the method can for example further comprise, when the water of the given water tank reaches the threshold temperature, operating the given water tank in a heat maintaining mode including: upon hot water demand, and while the corresponding cold water valve remains closed, dispensing a first quantity of water from the given water tank to the hot water line at afirst location thereof while filling the given water tank with a second quantity of water from the hot water line at a second location thereof, the second location upstream from the first location, the first quantity of water corresponding to the second quantity of water.

[0021] Still further in accordance with the second aspect of the present disclosure, said water filling the given water tank can for example have a temperature below 20°C, preferably below 15°C, and most preferably below 10°C.

[0022] Still further in accordance with the second aspect of the present disclosure, said temperature threshold can for example be at least 40°C, preferably at least 50°C and most preferably at least 60°C.

[0023] Still further in accordance with the second aspect of the present disclosure, the method can for example further comprise: upon detecting that a temperature of water circulating along the hot water line exceeds a given temperature threshold, injecting a quantity of cold water into the hot water line via a modulating valve fluidly connecting the hot water line and the cold water line.

[0024] Still further in accordance with the second aspect of the present disclosure, the water heating circuit can for example have a circulating pump forcing a flow of water from the given water tank to the water heater via the inlet conduit and back to the given water tank via the outlet conduit.

[0025] Still further in accordance with the second aspect of the present disclosure, the water heating circuit can for example be external to the plurality of water tanks.

[0026] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE FIGURES

[0027] In the figures,

[0028] Fig. 1 is a schematic view of a first example of a water heater system incorporating three water tanks operated in a parallel configuration, in accordance with one or more embodiments;

[0029] Fig. 2 is a flow chart of a method of operating the water heater system of Fig. 1 , in accordance with one or more embodiments;

[0030] Fig. 3 is a schematic view of an example of a water heater of the water heater system of Fig. 1, in accordance with one or more embodiments;

[0031] Fig. 3A is a schematic view of the water heater of Fig. 3 when operated in a heat charging mode, in accordance with one or more embodiments;

[0032] Fig. 3B is a schematic view of the water heater of Fig. 3 when operated in a heat maintaining mode, in accordance with one or more embodiments;

[0033] Fig. 3C is a schematic view of the water heater of Fig. 3 when operated in a heat discharging mode, in accordance with one or more embodiments;

[0034] Fig. 3D is a schematic view of the water heater of Fig. 4 when operated in a bypass mode, in accordance with one or more embodiments;

[0035] Fig. 4 is a schematic view of a second example of a water heater system incorporating three water tanks operated in a parallel configuration, in accordance with one or more embodiments; and

[0036] Fig. 5 is a block diagram showing an example embodiment of a controller, in accordance with one or more embodiments.DETAILED DESCRIPTION

[0037] Fig. 1 shows an example of a water heater system 10, in accordance with one or more embodiments. As depicted, the water heater system 10 has a number of water tanks 12 in fluid communication with a cold water line 14 and a hot water line 16. In this specific embodiment, the water heater system 10 includes three water tanks 12: namely a first water tank 12a, a second water tank 12b and a third water tank 12c. However, the water heatersystem 10 can have two water tanks, or more than three water tanks in some other embodiments. The cold water line 14 and the hot water line 16 can be common to a multi- residential building, for instance. The number of water tanks 12 can thus depend on the scale of the multi-residential buildings and overall hot water demand.

[0038] In some embodiments, each water tank 12 has a cold water inlet 18 in fluid communication with the cold water line 14 and a hot water outlet 20 in fluid communication with the hot water line 16. As shown in this embodiment, the cold water inlet 18 can be positioned at a bottom portion of the corresponding water tank 12 while the hot water outlet 20 can be positioned at a top portion of the corresponding water tank 12.

[0039] As illustrated, cold water valves 22 are in fluid communication between the cold water line 14 and the corresponding water tanks 12. For instance, a first cold water valve 22a fluidly connects the cold water inlet 18 of the first water tank 12a to the cold water line 14, a second cold water 22b valve fluidly connects the cold water inlet 18 of the second water tank 12b, a third cold water 22c valve fluidly connects the cold water inlet 18 of the third water tank 12c, and so forth. Examples of cold water valves can include, but are not limited to, motorized valves, electronic valves, ball-joint valves, and the like.

[0040] As colder water tends to be more dense and fall to the bottom of the water tank 12, hotter water tends to be less dense and reach the top of the water tank 12, as schematically shown in the second water tank 12b. During a normal mode of operation of the second water tank 12b, e.g., during a heat discharging mode, a hot water demand will result in a quantity of hotter water leaving the top portion of the second water tank 12b towards the hot water line 16. This can be achieved by momentarily opening the second cold water valve 22b, which will force colder water up and into the cold water inlet 18 of the second water tank 12b. In response, this new pressurized addition of water at the bottom of the second water tank 12b can force hotter water out of the second water tank 12b and into the hot water line 16 via the hot water outlet 20. Accordingly, upon hot water demand, one of the cold water valves 22 can be momentarily opened to fulfill any incoming hot water demand.

[0041] As shown, the water heater system 10 is provided with a water heating circuit 30 which has a water heater 32, a first inlet conduit 34a fluidly connecting the first water tank tothe water heater 32, and a first outlet conduit 36a fluidly connecting the water heater 32 to the first water tank 12a. As shown in this embodiment, the water heating circuit 30 can include a second inlet conduit 34b fluidly connecting the second water tank 12b to the water heater 32, and a second outlet conduit 36b fluidly connecting the water heater 32 to the second water tank 12b. The water heating circuit 30 can include a third inlet conduit 34c fluidly connecting the third water tank 12c to the water heater 32, and a third outlet conduit 36c fluidly connecting the water heater 32 to the third water tank 12c, and so forth for other water tanks, if any. In some embodiments, a dedicated water heating circuit can be provided for each of the water tanks. In these embodiments, a water heater is thus provided for each of the water tanks. However, in some other embodiments, a single water heater can be used by one or more water heating circuits. It is generally preferred to have a single water heater of large capacity for heating the water of all of the water tanks for efficiency purposes. Examples of such water heaters can include, but are not limited to, heat pump(s), electrically resistive heating circuit(s), burner(s), or a combination thereof. In some embodiments, the water heating circuit 30 has a circulating pump (not shown) forcing a flow of water from a given water tank to the water heater 32 via the corresponding inlet conduit 34 and back to the given water tank 12 via the corresponding outlet conduit 36. However, in some embodiments, such a circulating pump can be omitted as the flow of water can be induced via thermal convection fluidic movements, for instance. As shown, the water heating circuit 30 is generally external to the water tanks 12. At least in some circumstances, providing the water heating circuit 30 externally to the water tanks 12 can encourage the sharing of the water heating circuit 30 across all of the water tanks 12.

[0042] The water heater system 10 has a controller 40 which is communicatively coupled at least to the water heater 32 and to the cold water valves 22. The controller 40 typically has a processor, and a non-transitory memory which has stored thereon instructions that when executed by the processor perform certain steps. For instance, the controller 40 can selectively turn on or off the water heater 32. The controller 40 can selectively open or close any one of the cold water valves 22 as well. The controller 40 can selectively turn on or off the circulating pump of the water heating circuit 30, if any. Moreover, the controller 40 can selectively open or close a number of fluidic valves provided in the water heating circuit(s) 30, if any.

[0043] In this disclosure, the controller 40 is configured to, when a given water tank 12 is fully filled with water from the cold water line 14, operate the given water tank 12 in a heat charging mode including: while the corresponding cold water valve 22 remains closed, circulating the water across the water heating circuit 30. The circulation of the water across the water heating circuit 30 results in the heating of the water up to a temperature threshold. In some preferred embodiments, the heating step is performed in one uninterrupted heating session. Uninterruptingly heating the water from a colder temperature to the temperature threshold allows energy efficiency, especially when using heat pump(s) as the water heater 32. It is deemed that heating the cold water across a large temperature variation, for instance from 10°C up to 60°C, can be more efficient when using heat pump(s) than other conventional water heating mechanisms. As such, the heat charging mode described herein can harness the energy efficiency of the heat pump in a way that is not possible with normal water heaters, as they typically heat water on demand for only little temperature variations.

[0044] In some embodiments, the controller 40 ensures that while the first water tank 12a is operated in the heat charging mode, the second or third water tank 12b, 12c is operated in a mode of operation which, upon demand, allows hot water to be supplied via the hot water line 16. More specifically, the controller 40 can operate any one of the water tanks into one of a plurality of different modes of operation simultaneously. Referring to Fig. 1, the first water tank 12a is operated into a heat charging mode, the second water tank 12b is operated in a heat discharging mode, and the third water tank 12c is operated in a heat maintaining mode. Immediately prior to a water tank being operated in the heat discharging mode, that same water tank can be operated in a standby mode for a certain period of time. During that period, the cold water valve 22 and the flow to the water heating circuit 130 can be closed, thereby isolating the given water tank from the rest of the system. In some other embodiments, a water tank can be operated in a bypass mode which isolates that water tank from the water heater system when it is depleted from its hot water and when the water heater 32 is in the process of heating the water of another water tank, for instance.

[0045] The heat charging mode is typically initiated when it is detected that a water tank 12 is fully filled with water from the cold water line 14. In some embodiments, the water filling the corresponding water tank 12 has a temperature below 20°C, preferably below 15°C, andmost preferably below 10°C. In the heat charging mode, while the cold water valve 22 remains closed, the water filling the water tank is circulated across the water heating circuit 30 where it is heated up to a temperature threshold. In the depicted embodiment, while the first cold water valve 22a is closed, the water contained in the first water tank 12a is flowed across the water heating circuit 30. More specifically, the water is flowed along the first inlet conduit 34a to the water heater 32, and then back to the first water tank 12a via the first outlet conduit 36a. This flow of water forms a loop in which all the water of the first water tank 12a is heated up to the temperature threshold. In some embodiments, the temperature threshold is at least 40°C, preferably at least 50°C, and most preferably at least 60°C. Typically, when the heat charging mode is over, a water tank can be switched to the heat discharging mode or to the heat maintaining mode.

[0046] The heat discharging mode is a mode in which a momentary demand of hot water results in the momentary opening of the corresponding cold water valve 22. The heat discharging mode generally follows the heat charging mode and / or the heat maintaining mode. In this way, and as discussed above, a pressurized addition of cold water at the bottom of the water tank 12 forces hotter water out of the water tank 12 and into the hot water line 16. A water heater 32 can be operated in the heat discharging mode as long as it contains a sufficient amount of hot water, after which the water tank 12 is switched into the heat charging mode. For instance, when it is detected that a volume of hot water in the water tank 12 is below a given volume threshold, and / or that the volume of cold water in the water tank 12 is above a given threshold, the corresponding water tank 12 can be switched into the heat charging mode by the controller 40.

[0047] The heat maintaining mode can be used only after the heat charging mode as it requires a full body of hot water inside the corresponding water tank 12. As such, upon hot water demand, and while the corresponding cold water valve 22 remains closed, the heat maintaining mode includes the dispensing of a first quantity of water from the water tank 12 to the hot water line 16 at a first location 16a thereof and the filling of the water tank 12 with a second quantity of water from the hot water line at a second location 16b thereof. In this embodiment, the second location 16b is upstream from the first location 16a along the hot water line. The first quantity of water also corresponds to the second quantity of water.

[0048] The water tanks 12 are operated in such a manner that i) a hot water demand can always be fulfilled (either by a water tank operated in the heat maintaining mode or the heat discharging mode), and ii) at least one of the water tanks is in the heat charging mode. At a later moment in time, the first water tank 12a can be operated in the heat maintaining mode while the second water tank 12b can be operated in the heat charging mode and the third water tank 12c can be operated in the heat discharging more. At yet another later moment in time, the first water tank 12a can be operated in the heat discharging mode while the second water tank 12b can be operated in the heat maintaining mode and the third water tank 12c can be operated in the heat charging mode. As such, each of the water tanks 12 can be operated in the heat charging mode for a first period of time, in the heat maintaining mode for a second period of time subsequent to the first period of time, in the heat discharging mode for a third period of time subsequent to the second period of time, in the heat charging mode for a fourth period of time subsequent to the third period of time, and so forth. It is intended that a water tank operated in the heat charging mode is temporarily isolated from the hot water line 16, and cannot fulfill hot water demand, which can be performed by the other water tanks 12 operated in the other modes of operation. In some embodiments, the heat maintaining mode is omitted. Such an isolation of the water tank operated in the heat charging mode can allow the water to be heated up to the temperature threshold in a single uninterrupted heating session.

[0049] Fig. 2 shows an exemplary flow chart of a method 200 of operating the water heater system of Fig. 1, in accordance with one or more embodiments.

[0050] At step 202, a given water reservoir is fully filled with water from the cold water line. It is intended that the term “fully filled” is not meant to be limiting in any means, as it refers to a desired volume of water which is fully filled rather than a total capacity of the corresponding water reservoir. In other words, the given water reservoir can be fully filled up to three quarter of its capacity if the desired volume of water for that given water reservoir is three quarter of its capacity.

[0051] At step 204, while a corresponding cold water valve remains closed, water is circulated around a flow loop extending from the given water tank to the water heater andback to the given water tank via the corresponding inlet and outlet conduits. The step 204 includes a step of heating the water up to a temperature threshold.

[0052] At step 206, the given water tank is operated in a heat maintaining mode. In this mode, upon hot water demand, and while the corresponding cold water valve remains closed, the step 206 includes a step of dispensing a first quantity of water from the first water tank to the hot water line at a first location thereof and filling the first water tank with a second quantity of water from the hot water line at a second location thereof. The latter step of filling can be simultaneous to the former step of dispending, in some embodiments. In any way, the second location is upstream from the first location along the hot water line. The first quantity of water corresponds to the second quantity of water.

[0053] Fig. 3 shows another example of a water heater system 110, in accordance with one or more embodiments. As shown, the water heater system 110 has a first water tank 112 in fluid communication with a cold water line 114 and a hot water line 116. The outlet 120 of the first water tank 112 is in fluid communication with the hot water line 116, and an anti-return valve 117 is provided between the outlet 120 and the hot water line 116. The antireturn valve 117 is installed in an horizontal manner in this embodiment, but its configuration can differ in some other embodiments. Although the water heater system 110 shows only one water tank 112, it is understood that one or more other water tanks are connected to the cold water line 114 and the hot water line 116. The water tanks 112 are thus connected in parallel to one another in this specific embodiment. The other water tanks can be connected in series to one another in some other embodiments.

[0054] As shown, a first cold water valve 122 is in fluid communication between the cold water line 114 and the first water tank 112. The water heater system 110 has a water heating circuit 130 having a water heater 132, a first inlet conduit 134 fluidly connecting the first water tank 112 to the water heater 132, and a first outlet conduit 136 fluidly connecting the water heater 132 to the first water tank 112. As can be understood, the water heating circuit 130 is only partially shown in this figure. More specifically, the water heater 132 is not shown other than for some reference numeral.

[0055] Temperature sensors 150 are positioned across the whole system 110. For instance, a first temperature sensor 150a is provided along the hot water line, at a location downstream from where the first water tank is fluidly connected, a second temperature sensor 150b is provided downstream from the outlet of the first water tank, a third temperature sensor 150c is provided downstream from the inlet of the first water tank, and so forth. An example of such a temperature sensors can include, but is not limited to, the Thermowell NPT %” model and the like. The readings from the temperature sensor(s) can be used by a controller to determine whether the water tank 112 should be switched from a current mode of operation to a subsequent mode of operation, for instance.

[0056] Fig. 3A shows the water heater system 110 of Fig. 3 when operated in the heat charging mode. As shown, while the cold water valve 122 remains closed, the water heating circuit is used to circulate the water along the inlet conduit 134 to the water heater 132, and back to the water tank 112 via the outlet conduit 136. As shown, the outlet of the water tank 112 is fluidly connected to the hot water line 116. However, as the cold water valve 122 remains closed, no pressurized flow of water can force hot water out of the heating loop and into the hot water line 116. In this embodiment, the outlet conduit 136 of the water heating circuit is connected to the water tank 122 via a controllable valve 123.

[0057] Fig. 3B shows the water heater system 110 of Fig. 3 when operated in the heat maintaining mode. As depicted, upon hot water demand, and while the cold water valve 122 remains closed, the water heater system 110 is operated to dispense a first quantity of water from the first water tank 112 to the hot water line 116 at a first location 116a thereof to fill the first water tank 112 with a second quantity of water from the hot water line 116 at a second location 116b thereof. As shown, the second location is upstream from the first location along the hot water line. Typically, as in any fluidic system, the first quantity of water typically corresponds to the second quantity of water, i.e. , the amount of water dispensed at the first location of the hot water line 116 pulls a corresponding amount of water from the second location of the hot water line 116. More specifically, in this example, a hot water conduit fluidly connects the hot water line 116 at the second location 116b with the cold water inlet 114 of the water tank 112. As such, even if the water pulled from the hot water line 116 is deemed to be hot, it can be cooler than the heated water incoming from the outlet conduit136. As such, the water heating system 110 can be used to heat the water up to the temperature threshold while the water tank 112 is in the heat maintaining mode.

[0058] Fig. 3C shows the water heater system 110 of Fig. 3 when operated in the heat discharging mode. As illustrated, upon hot water demand, the cold water valve 122 is opened thereby receiving into the water tank 112 a first quantity of water from the cold water line 114 while dispensing water from the first water tank 112 to the hot water line 116.

[0059] The controller 40 described with reference to Fig. 1 can be provided as a combination of hardware and software components. The hardware components can be implemented in the form of a computing device 500, an example of which is described with reference to Fig. 5. Moreover, the software components of the controller can be implemented in the form of one or more software applications.

[0060] Fig. 3D shows the water heater system 110 of Fig. 3 when operated in the bypass mode. In some embodiments, the water tank 112 is operated in the bypass mode when two conditions are met: i) when the given water tank 112 is totally depleted of hot water, and ii) when another one of the water tanks is being operated in the heat charging mode, and therefore the water heater 132 is fully occupied into heating the water of that other water tank, e.g., during one interrupted session. In the bypass mode, hot water is not circulated into the given water tank 112 in any way, either from the outlet conduit 136 or from the hot water line 116, nor is cold water allowed to fill the water tank 112. As such, the cold water valve 112 is closed, the controllable valve 123 is closed as well as flow of water incoming from the second location 116b of the hot water line 116.

[0061] Fig. 4 shows an example of a water heater system 410, in accordance with one or more embodiments. As depicted, the water heater system 410 has a number of water tanks 412 in fluid communication with a cold water line 414 and a hot water line 416. In this specific embodiment, the water heater system 410 includes three water tanks 412: namely a first water tank 412a, a second water tank 412b and a third water tank 412c. As discussed above, the cold water line 414 and the hot water line 416 can be common to a multi- residential building, for instance. The number of water tanks 412 can thus depend on the scale of the multi-residential buildings and overall hot water demand. In some embodiments,each water tank 412 has a cold water inlet 418 in fluid communication with the cold water line 414 and a hot water outlet 420 in fluid communication with the hot water line 416. As shown in this embodiment, the cold water inlet 418 can be positioned at a bottom portion of the corresponding water tank 412 while the hot water outlet 420 can be positioned at a top portion of the corresponding water tank 412.

[0062] As illustrated, cold water valves 422 are in fluid communication between the cold water line 414 and the corresponding water tanks 412. For instance, a first cold water valve 422a fluidly connects the cold water inlet 418 of the first water tank 412a to the cold water line 414, a second cold water 422b valve fluidly connects the cold water inlet 418 of the second water tank 412b, a third cold water 422c valve fluidly connects the cold water inlet 418 of the third water tank 412c, and so forth. In this specific example, a number of additional valves are used to facilitate water flow across the water heater system 410. For instance, hot water valves 417a, 417b and 417c are provided between the hot water outlets 420 of the respective ones of water tanks 412a, 412b and 412c and the hot water line 416. In this specific example, the hot water valves 417a, 417b and 417c are provided in the form of check valves. However, in some other embodiments, other valve types can be envisaged. The inlet and outlet conduits 434 and 436 are also connected to the water tanks 412a, 412b and 412c with respective heater inlet and outlet valves 421 and 419. More specifically, a first heater outlet valve 419a fluidly connects the first water tank 412a to the outlet conduit 436, a second heater outlet valve 419b fluidly connects the second water tank 412b to the outlet conduit 436, and a third heater outlet valve 419c fluidly connects the third water tank 412c to the outlet conduit 436. The heater outlet valves 419 are provided in the form of check valves, for instance. Moreover, a first heater inlet valve 421a fluidly connects the first water tank 412a to the inlet conduit 434, a second heater inlet valve 421b fluidly connects the second water tank 412b to the inlet conduit 434, and a third heater inlet valve 421c fluidly connects the third water tank 412c to the inlet conduit 434. In this specific example, the heater inlet valves 421 are provided in the form of two-way valves. The configuration of the water heater system 410 is meant to be exemplary only, as other satisfactory connection or valve configurations can be used in some other embodiments.

[0063] As depicted, modulating valves 423a, 423b and 423c are fluidly connected between the hot water line 416 and the cold water inlets 418 of the first, second and third water tanks 412a, 412b and 412c, respectively. In this embodiment, these modulating valves can be operated to allow any one of the water tanks 412a, 412b and 412c to be operated a heat maintaining mode. For instance, the third water tank 112c is being operated in the heat maintaining mode in which hot water returning from the hot water circuit is fed back into the third water tank 112c where hot water is kept at a high temperature. In some embodiments, the hot water returning from the hot water circuit can be a little cooler than the hot water kept within the water tank, e.g., it can be at a temperature as low as 50-55°C in some embodiments. Accordingly, the water tank operated in the heat discharging mode, namely the second water tank 412b in this example, can be used to discharge hot water (hotter than 55°C) along the hot water line 416 to help heat the hot water circulating along the hot water line 416 to reach a desired temperature, e.g., 60°C. Temperature sensors 450a, 450b and 450c spaced apart from each other along the hot water line 416, and located downstream from respective ones of the hot water valves 417a, 417b and 417c are provided in this example. The real-time or quasi real time readings of the temperature sensors 450a, 450b and 450c can be used as a basis to determine whether hot water has to be discharged into the hot water circuit to reach an acceptable hot temperature threshold.

[0064] Additionally or alternately, an end modulating valve 423 can be fluidly connected between the cold water line and the hot water line 416, downstream from the temperature sensor 450c, i.e. , the downstream most of the temperature sensors along the hot water line 416. In this embodiment, the end modulating valve 423 can inject some cold water along the hot water line 416 when a temperature of the hot water circulating along the hot water line 416 is hotter than a given temperature threshold. The injection of cold water along the hot water line 416 can be based on temperature readings from the third temperature detector 450c or an end temperature sensor 450d, depending on the embodiment. Such an end modulating valve can be useful in situations where the water heater 432 is configured to heat the water up to 70°C to 90°C. For instance, new generations heat pumps (e.g., using more efficient refrigerants) or electric heating systems can be configured to heat water up to these high temperatures. Accordingly, in some embodiments, using a water heater configured to heat to these high temperatures can be advantageous from energy-saving purposes.However, as hotter than safe water can be obtained, the end modulating valve 423 can be operated to mix more or less cold water along the hot water line 416 to reduce the temperature of the hot water to acceptable safe levels. As illustrated, the temperature sensors, the valves and the water heater are communicatively coupled to a controller 440 which can control operation of the whole water heater system 410 as desired based on a number of preprogrammed processor executable instructions stored onto a non-volatile computer memory thereof.

[0065] Referring to Fig. 5, the computing device 500 can have a processor 502, a memory 504, and I / O interface 506. Instructions 508 for running the one or more software applications can be stored on the memory 504 and accessible by the processor 502.

[0066] The processor 502 can be, for example, a general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, a programmable read-only memory (PROM), or any combination thereof.

[0067] The memory 504 can include a suitable combination of any type of computer- readable memory that is located either internally or externally such as, for example, randomaccess memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable readonly memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

[0068] Each I / O interface 506 enables the computing device 500 to interconnect with one or more input devices, or with one or more output devices.

[0069] Each I / O interface 506 enables the controller to communicate with other components, to exchange data with other components, to access and connect to network resources, to server applications, and perform other computing applications by connecting to a network (or multiple networks) capable of carrying data including the Internet, Ethernet, plain old telephone service (POTS) line, public switch telephone network (PSTN), integrated services digital network (ISDN), digital subscriber line (DSL), coaxial cable, fiber optics,satellite, mobile, wireless (e.g. Wi-Fi, WiMAX), SS7 signaling network, fixed line, local area network, wide area network, and others, including any combination of these.

[0070] The computing device 500 and the software layers described above are meant to be examples only. Other suitable embodiments of the controller can also be provided, as it will be apparent to the skilled reader.

[0071] It will be understood that the computing device 500 can perform functions or processes via hardware or a combination of both hardware and software. For example, hardware can include logic gates included as part of a silicon chip of a processor. Software (e.g. application, process) can be in the form of data such as computer-readable instructions stored in a non-transitory computer-readable memory accessible by one or more processing units. With respect to a computer or a processing unit, the expression “configured to” relates to the presence of hardware or a combination of hardware and software which is operable to perform the associated functions.

[0072] As can be understood, the examples described above and illustrated are intended to be exemplary only. In these embodiments, the water tanks can be configured to be operated in cycles including a period of time in the heat charging mode, a successive period of time in the heat maintaining mode and a successive period of time in the heat discharging mode. In some embodiments, the heat source is provided in the form of a heat pump. It is noted that the heat pump can offer desirable energy consumption and efficiency when larger water temperature variations are needed, and may not be as energy efficient when the water is to be heated only a little. Accordingly, when operating in the heat charging mode, the cold water filling the whole water tank can be heated up to a desired temperature with optimal energy efficiency using the heat pump. In contrast, existing water tanks typically avoid the heating of a water tank full of cold water as the (electrically resistive) heating elements are often times inefficient for larger temperature variations. As such, existing water tanks tend to prefer the incremental, successive heating of the water to avoid such large temperature variations. The scope is indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A water heater system comprising: first and second water tanks in fluid communication with a cold water line and a hot water line; a first cold water valve in fluid communication between the cold water line and the first water tank; a water heating circuit having a water heater, a first inlet conduit fluidly connecting the first water tank to the water heater, and a first outlet conduit fluidly connecting the water heater to the first water tank; and a controller communicatively coupled to the water heater and the first cold water valve, the controller configured for: when the first water tank is fully filled with water from the cold water line, operating the first water tank in a heat charging mode including: while the first cold water valve remains closed, circulating said water across the water heating circuit, said circulating including heating the water up to a temperature threshold.

2. The water heater system of claim 1 wherein said heating is performed in one uninterrupted heating session.

3. The water heater system of claim 1 wherein while the first water tank is operated in the heat charging mode, the second water tank is operated in a normal mode of operation which, upon demand, allows hot water to be supplied via the hot water line.

4. The water heater system of claim 1 further comprising a second cold water valve in fluid communication between the cold water line and the second water tank, the water heating circuit having a second inlet conduit and a second outlet conduit fluidly connecting the second water tank and the water heater to one another, the controllerfurther configured for switching the second water tank from a normal mode of operation to a corresponding heat charging mode.

5. The water heater system of claim 4 further comprising, upon said switching the second water tank from a normal mode of operation to a corresponding heat charging mode, switching the first water tank from the heat charging mode to a mode of operation which, upon demand, allows water having a temperature above the temperature threshold to be supplied via the hot water line.

6. The water heater system of claim 1 further comprising, when the water of the first water tank reaches the threshold temperature, operating the first water tank in a heat maintaining mode including: upon hot water demand, and while the first cold water valve remains closed, dispensing a first quantity of water from the first water tank to the hot water line at a first location thereof and filling the first water tank with a second quantity of water from the hot water line at a second location thereof, the second location upstream from the first location, the first quantity of water corresponding to the second quantity of water.

7. The water heater system of claim 1 further comprising, when the water of the first water tank reaches the threshold temperature, operating the first water tank in a heat discharging mode including: upon hot water demand, opening the first cold water valve thereby receiving into the first water tank a first quantity of water from the cold water line and dispensing water from the first water tank to the hot water line.

8. The water heater system of claim 1 wherein the water heater includes a heat pump.

9. The water heater system of claim 1 wherein said water filling the first water tank has a temperature below 20°C, preferably below 15°C, and most preferably below 10°C.

10. The water heater system of claim 1 wherein said temperature threshold is at least 40°C, preferably at least 50°C, and most preferably at least 60°C.

11. The water heater system of claim 1 wherein the water heating circuit has a circulating pump forcing a flow of water from the first water tank to the water heater via the first inlet conduit and back to the first water tank via the first outlet conduit.

12. The water heater system of claim 1 wherein the water heating circuit is external to the first and second water tanks.

13. A method of operating a water heater system, the water heater system having a plurality of water tanks in fluid communication with a cold water line and a hot water line; a plurality of cold water valves in fluid communication between a corresponding one of the plurality of water tanks and the cold water line; and a water heating circuit having a water heater, inlet conduits fluidly connecting the water tanks to the water heater, and outlet conduits fluidly connecting the water heater to the water tanks, the method comprising: upon determining that a given water tank of the plurality of water tanks is fully filled with water from the cold water line, operating the given water tank in a heat charging mode including: while the corresponding cold water valve remains closed, circulating said water across said water heating circuit, said circulating including heating the water up to a temperature threshold.

14. The method of claim 13 wherein said heating is performed in one uninterrupted heating session.

15. The method of claim 13 wherein while the given water tank is operated in the heat charging mode, at least another one of the plurality of water tanks is operated in a normal mode of operation which, upon demand, allows hot water to be supplied via the hot water line.

16. The method of claim 13 further comprising, when the water of the given water tank reaches the threshold temperature, operating the given water tank in a heat maintaining mode including: upon hot water demand, and while the corresponding cold water valve remains closed, dispensing a first quantity of water from the given water tank to the hot water line at a first location thereof and filling the given water tank with asecond quantity of water from the hot water line at a second location thereof, the second location upstream from the first location, the first quantity of water corresponding to the second quantity of water.

17. The method of claim 13 wherein at least one of: said water filling the given water tank has a temperature below 20°C, preferably below 15°C, and most preferably below 10°C, and said temperature threshold is at least 40°C, preferably at least 50°C and most preferably at least 60°C.

18. The method of claim 13 further comprising upon detecting that a temperature of water circulating along the hot water line exceeds a given temperature threshold, injecting a quantity of cold water into the hot water line via a modulating valve fluidly connecting the hot water line and the cold water line.

19. The method of claim 13 wherein the water heating circuit has a circulating pump forcing a flow of water from the given water tank to the water heater via the inlet conduit and back to the given water tank via the outlet conduit.

20. The method of claim 13 wherein the water heating circuit is external to the plurality of water tanks.

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