Compact and centralized heat pump water heater SKID package

Abstract

One embodiment provides a compact and centralized heat pump water heater system comprising a modular skid and a master controller for controlling the system. The skid includes a stratified primary storage tank for storing cold water and hot water, and an array of heat pumps for heating the cold water into the hot water. The storage tank is disposed inside the skid. The heat pumps are mounted onto an exterior of the skid. The hot water is supplied to a building structure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 558,756, filed on Feb. 28, 2024, incorporated herein by reference.TECHNICAL FIELD

[0002] One or more embodiments relate generally to water heating systems, and in particular, a compact and centralized heat pump water heater skid package for water heating applications.BACKGROUND

[0003] Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Example domestic and industrial uses of hot water include cooking, cleaning, bathing, space heating, etc. A water heating system is an important part of domestic dwellings such as single family homes, apartment buildings, and multi-family residential buildings, and commercial or industrial buildings such as senior living facilities, hotels, office buildings, factories, hospitals, etc. In the United States, hot water is most commonly heated with natural gas, electric resistance, or a heat pump. Electric heat pump water heaters are significantly more efficient than electric resistance water heaters.SUMMARY

[0004] One embodiment provides a compact and centralized heat pump water heater system comprising a modular skid and a master controller for controlling the system. The skid includes a stratified primary storage tank for storing cold water and hot water, and an array of heat pumps for heating the cold water into the hot water. The storage tank is disposed inside the skid. The heat pumps are mounted onto an exterior of the skid. The hot water is supplied to a building structure.

[0005] Another embodiment provides a compact and centralized heat pump water heater system comprising a modular primary skid, a modular secondary skid, and a master controller for controlling the system. The primary skid includes a first stratified storage tank for storing cold water and hot water, and a first array of heat pumps for heating the cold water into the hot water. The first stratified storage tank is disposed inside the primary skid. The first array of heat pumps are mounted onto an exterior of the primary skid. The secondary skid includes at least one additional stratified storage tank for storing the cold water and the hot water, and a second array of heat pumps for heating the cold water into the hot water. The at least one additional stratified storage tank is disposed inside the secondary skid. The second array of heat pumps are mounted onto an exterior of the secondary skid. The hot water is supplied to a building structure.

[0006] These and other features, aspects and advantages of the present invention will become understood with reference to the following description, appended claims and accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0008] FIG. 1A illustrates a front view of an example compact, centralized, and modular heat pump water heater (HPWH) system, in one or more embodiments;

[0009] FIG. 1B illustrates a top view of the system in FIG. 1A, in one or more embodiments;

[0010] FIG. 1C illustrates a schematic view of the system in FIG. 1A, in one or more embodiments;

[0011] FIG. 1D illustrates a perspective view of an interior of the skid in FIG. 1A, in one or more embodiments;

[0012] FIG. 1E illustrates a perspective view of the system in FIG. 1A with more heat pumps, in one or more embodiments;

[0013] FIG. 2A illustrates a front view of an example storage tank, in one or more embodiments;

[0014] FIG. 2B illustrates a side view of the storage tank in FIG. 2A, in one or more embodiments;

[0015] FIG. 2C illustrates a top view of the storage tank in FIG. 2A, in one or more embodiments;

[0016] FIG. 3A illustrates a front view of another example compact, centralized, and modular HPWH system, in one or more embodiments;

[0017] FIG. 3B illustrates a top view of the system in FIG. 3A, in one or more embodiments;

[0018] FIG. 3C illustrates a schematic view of the system in FIG. 3A, in one or more embodiments;

[0019] FIG. 3D illustrates a top view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0020] FIG. 3E illustrates a front view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0021] FIG. 3F illustrates a right side view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0022] FIG. 3G illustrates a left side view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0023] FIG. 3H illustrates a front view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0024] FIG. 3I illustrates a right side view of the primary skid of the system in FIG. 3A, in one or more embodiments;

[0025] FIG. 3J illustrates a top view of the secondary skid of the system in FIG. 3A, in one or more embodiments;

[0026] FIG. 3K illustrates a front view of the secondary skid of the system in FIG. 3A, in one or more embodiments;

[0027] FIG. 3L illustrates a left side view of the secondary skid of the system in FIG. 3A, in one or more embodiments;

[0028] FIG. 3M illustrates a left side view of the secondary skid of the system in FIG.

[0029] 3A, in one or more embodiments;

[0030] FIG. 3N illustrates a front view of the secondary skid of the system in FIG. 3A, in one or more embodiments; and

[0031] FIG. 3O illustrates an underside of each skid of the system 200 in FIG. 3A, in one or more embodiments.

[0032] The detailed description explains the preferred embodiments of the invention together with advantages and features, by way of example with reference to the drawings.DETAILED DESCRIPTION

[0033] One or more embodiments relate generally to water heating systems, and in particular, a compact and centralized heat pump water heater skid package for water heating applications. One embodiment provides a compact and centralized heat pump water heater system comprising a modular skid and a master controller for controlling the system. The skid includes a stratified primary storage tank for storing cold water and hot water, and an array of heat pumps for heating the cold water into the hot water. The storage tank is disposed inside the skid. The heat pumps are mounted onto an exterior of the skid. The hot water is supplied to a building structure.

[0034] Another embodiment provides a compact and centralized heat pump water heater system comprising a modular primary skid, a modular secondary skid, and a master controller for controlling the system. The primary skid includes a first stratified storage tank for storing cold water and hot water, and a first array of heat pumps for heating the cold water into the hot water. The first stratified storage tank is disposed inside the primary skid. The first array of heat pumps are mounted onto an exterior of the primary skid. The secondary skid includes at least one additional stratified storage tank for storing the cold water and the hot water, and a second array of heat pumps for heating the cold water into the hot water. The at least one additional stratified storage tank is disposed inside the secondary skid. The second array of heat pumps are mounted onto an exterior of the secondary skid. The hot water is supplied to a building structure.

[0035] One or more embodiments of the invention may be used in different thermal energy storage systems providing heating and / or cooling in, for example, residential structures for domestic dwelling (e.g., multi-family residential buildings, etc.) or commercial / industrial structures for commercial / industrial use (e.g., office buildings, factories, etc.).

[0036] Today, challenges faced by commercial water heating systems are manifold. Some challenges include custom complex designs and installations, space constraints, environmental impact, and limited adaptability. Conventional solutions for water heating often involve intricate and time-consuming design and installation processes, escalating costs, and necessitate specialized expertise, which in turn hinders widespread implementation. Additionally, these conventional solutions typically demand substantial space or retrofitting older buildings which poses challenges in urban settings where space is at a premium. Many conventional solutions utilize refrigerants with high global warming potential (GWP), thereby contributing significantly to environmental issues. These conventional solutions often suffer from inefficiencies leading to increased energy consumption and operational costs. Moreover, the lack of modular and scalable designs in conventional solutions for water heating limit its adaptability to specific building needs, especially in multifamily residential buildings or commercial buildings.

[0037] To address these challenges, one or more embodiments of the invention provide compact, modular, and centralized heat pump water heater (HPWH) systems of varying sizes. Each HPWH system is a skid package, i.e., a self-contained unit that houses equipment and parts for heating water. Specifically, each HPWH system comprises fully modular, skid-mounted components (i.e., equipment and parts that are mounted onto a skid) that are deliverable within a single delivery as a pre-fabricated package (or system in a box) for plug-and-play. Each HPWH system is designed for factory fabrication and easy installation. Each HPWH system includes components for primary water heating and temperature maintenance such as, but not limited to, one or more heat pumps, one or more stratified storage tanks, one or more temperature maintenance tanks, one or more all pumps, one or more expansion tanks, one or more mixing valves, one or more power landings, and one or more controls. All components of a HPWH system are mounted onto or housed within one or more skids, thereby reducing footprint and upfront costs including shipping expenses; this efficient arrangement utilizes one or more heat pumps with high heating capacity and minimal greenhouse gas emissions. As described in detail later herein, each HPWH system is designed to ensure optimal operation with multiple heat pumps connected in parallel, enhancing redundancy and reliability. For example, in one embodiment, a HPWH system is capable of generating heat ranging from 31 kBtu to 185 kBtu.

[0038] Interested customers can select a desired HPWH system from a catalog of pre-engineered and fully-assembled HPWH systems of different sizes. The HPWH systems available for selection are versatile, catering to a variety of building sizes, and addressing key market concerns of installation complexity, space efficiency / constraints, and environmental impact. The HPWH systems available for selection allow for greater flexibility and adaptability, making it suitable for a diverse range of building sizes and requirements. A distributor that a desired HPWH system is ordered from can deliver on-site the desired HPWH system. Each HPWH system's comprehensive, all-in-one design simplifies installation, requiring only plug-and-play with water and power connections available on-site. Furthermore, unlike many conventional solutions for water heating, each HPWH system utilizes low GWP refrigerants, thereby minimizing the system's environmental footprint.

[0039] The utility of each HPWH system extends beyond its compactness and eco-friendliness. Each HPWH system's pre-engineered design eliminates the need for customized engineering and system design which in turn significantly reduces time and costs associated with conventional custom installations. This streamlined approach allows for ease of installation and reliable operation, making it accessible to a wider range of users, including those without specialized knowledge of water heating systems. Due to its ability to overcome common challenges faced by conventional solutions for water heating, each HPWH system simplifies the design process, simplifies the installation process, reduces physical space requirements, lowers greenhouse gas emissions with use of eco-friendly refrigerants, and provides a versatile solution adaptable to various building sizes. Each HPWH system's pre-engineered, easy-to-install nature ensures consistent, reliable operation, addressing the complexities and inefficiencies often associated with conventional water heating systems.

[0040] One or more embodiments of the invention provide a drop-in modular HPWH system that is scalable to any building size and that is fossil fuel free.

[0041] FIG. 1A illustrates a front view of an example compact, centralized, and modular heat pump water heater (HPWH) system 100, in one or more embodiments. FIG. 1B illustrates a top view of the system 100 in FIG. 1A, in one or more embodiments. FIG. 1C illustrates a schematic view of the system 100 in FIG. 1A, in one or more embodiments. As shown in FIGS. 1A-1C, all components (i.e., equipment and parts) of the system 100 are mounted onto or housed within a single skid 110. In one embodiment, the skid 110 is an enclosure comprising a steel frame 50 (FIG. 1D) with removable insulated side panels (e.g., side panels 110A, 110B, and 110T, etc.).

[0042] In one embodiment, the components of the system 100 include, but are not limited to, the following: (1) an array of heat pumps 120 for heating water, (2) one power connection panel 130 for power landing, (3) one stratified primary storage tank 140 for storing water, (4) one swing tank 150 for maintaining a setpoint temperature (e.g., 120° F.) in a hot water recirculation loop 190, (5) one expansion tank 160 for preventing excessive water pressure as the system 100 heats up water, (6) a plurality of water connections 170 for exchanging water with a building the system 100 is located at, and (7) a plurality of piping connections 180 for drainage.

[0043] In one embodiment, each heat pump 120 is a carbon dioxide (CO2) heat pump that uses CO2 as a refrigerant. In one embodiment, each heat pump 120 allows for hot water production even when ambient temperatures fall to −20° F. or below.

[0044] In one embodiment, the array of heat pumps 120 is mounted onto an exterior of the skid 110. For example, in one embodiment, the heat pumps 120 are arranged and distributed across an exterior of a front side panel 110A of the skid 110, as shown in FIG. 1A.

[0045] In one embodiment, the array of heat pumps 120 include, but is not limited to, four (4) heat pumps 120. In another embodiment, the array of heat pumps 120 include a different number of heat pumps 120 instead (e.g., six (6) heat pumps 120, as shown in FIG. 1E).

[0046] In one embodiment, the power connection panel 130 is mounted onto an exterior of the skid 110. For example, in one embodiment, the power connection panel 130 is mounted onto an exterior of a left side panel 110B of the skid 110, as shown in FIG. 1A.

[0047] FIG. 1D illustrates a perspective view of an interior of the skid 110 in FIG. 1A, in one or more embodiments. For illustration purposes, some side panels of the skid 110 are removed to show the interior of the skid 110 in FIG. 1D. The system 100 is fitted into the frame 50 and mounted onto the skid 110.

[0048] As shown in FIG. 1C-1D, in one embodiment, the storage tank 140, the swing tank 150, and the expansion tank 160 are housed inside of the skid 110. As further shown in FIG. 1C, the plurality of water connections 170 (FIGS. 1A-1B) include a hot water recirculation return 170A (e.g., a 1½ inch copper stub) for returning hot water to the system 100, a cold water inlet 170B (e.g., a 2 inch copper stub) for receiving cold water (e.g., 55° F.) from the building, and a hot water outlet 170C (e.g., a 2 inch copper stub) for supplying hot water to the building.

[0049] In one embodiment, the storage tank 140 includes a cold water inlet port 143 for receiving cold water (e.g., from the cold water inlet 170B). The storage tank 140 includes a heat pump supply port 146 for supplying cold water stored (towards the bottom of the storage tank 140) to the heat pumps 120 for heating. Each heat pump 120 includes a cold water inlet 120A for drawing cold water (e.g., from the storage tank 140) which it then heats. Each heat pump 120 includes a hot water outlet 120B for supplying hot water to the storage tank 140 for storage.

[0050] In one embodiment, the storage tank 140 includes a heat pump return port 144 for receiving hot water from the heat pumps 120 which it then stores. The storage tank 140 includes a hot water outlet port 145 for supplying hot water stored (towards the top of the storage tank 140) to the swing tank 150.

[0051] In one embodiment, the swing tank 150 includes a hot water inlet port 151 for receiving hot water (e.g., from the storage tank 140 or the hot water recirculation loop 190) which it maintains the setpoint temperature of (e.g., 120° F.). The swing tank 150 includes a hot water outlet port 152 for supplying hot water (e.g., either to the building via the hot water outlet 170C or for recirculation via the hot water recirculation loop 190).

[0052] In one embodiment, the system 100 includes one or more temperature sensors 141 (i.e., temperature probes). For example, in one embodiment, the storage tank 140 includes at least one temperature sensor 141 disposed within a thermowell 142 (FIG. 2A) of the storage tank 140. In one embodiment, the system 100 includes one or more flow monitors to monitor pressure as water flows through the system 100.

[0053] In one embodiment, each tank 140, 150 includes a temperature and pressure relief port 147, 153 for relieving an excessive amount of pressure or heat in the tank 140, 150, thereby protecting the tank 140, 150 from any damage the excessive amount might have caused.

[0054] In one embodiment, the piping connections 180 include, but are not limited to, the following: a heat pump condensate drain (e.g., heat pump condensate drain 290B in FIG. 3H, heat pump condensate drain 295B in FIG. 3N) (e.g., a ½ inch PVC stub) for drainage of condensation from the heat pumps 120, and tank temperature and pressure drains (e.g., tank temperature and pressure drains 290A and 290C in FIG. 3H, tank temperature and pressure drains 295A and 295C in FIG. 3N) (e.g., ¾ inch copper stubs) for drainage of any water leaks from each tank 140, 150 after all excess air escapes from the tank 140, 150 via its temperature and pressure relief port 147, 153.

[0055] In one embodiment, the system 100 includes a master mixing valve 191, one or more balancing valves 193, one or more check valves 194, and a recirculation pump 192. Together with the swing tank 150, the master mixing valve 191 and the recirculation pump 192 help to maintain the setpoint temperature (i.e., target temperature) of the water in the hot water recirculation loop 190 to recover standby losses during periods of low hot water usage in the building. The swing tank 150 keeps primary storage of water in the storage tank 140 separate from the hot water recirculation loop 190, and provides thermal storage to maintain the setpoint temperature. In one embodiment, the swing tank 150 includes an electrical element that maintains the setpoint temperature during extended periods of no water usage in the building. The swing tank 150 increases the efficiency of the heat pumps 120 by ensuring that the heat pumps 120 only heat cold water. Further, the swing tank 150 provides extra capacity beyond the capabilities of the heat pumps 120 for extreme draws (i.e., extreme water usage in the building).

[0056] Containing the system 100 within the skid 110 allow for easy delivery and installation of a large-scale water heating system, i.e., the skid 110 allows the system 100 to be easily transported and integrated. The skid 110 is delivered pre-engineered and pre-packaged to the site of the building when the skid 110 is ready to be installed. In one embodiment, an exterior of a top side panel 110T of the skid 110 includes one or more lift points 111 (e.g., rigging eyelets with substantially about 1 inch through holes). For example, in one embodiment, each corner of the exterior of the top side panel 110T includes a lift point 111 positioned within proximity of the corner, as shown in FIG. 1B. The lift points 111 allow the entire skid 110 to be rigged such that a crane or a forklift can lift the skid 110 and drop-in the skid 110 into position. The skid 110 may be positioned onto a flat surface, such as on the rooftop of the building or on the ground adjacent to the building. In one embodiment, one or more tie down points 112 extend from an underside 110U of the skid 110 for securing the skid 110 onto the surface. As shown in FIG. 1B, in one embodiment, the tie down points 112 include corner base plates 112A at corners of the underside 110U, side mounts 112B at a first pair of opposing sides of the underside 110U, and side mounts 112C at a second pair of opposing sides of the underside 110U. Each corner base plate 112A and each side mount 112B, 112C is secured to the surface via anchor bolts.

[0057] In one embodiment, the skid 110 is a fully insulated enclosure (i.e., the steel frame 50 (FIG. 1D) includes the insulated side panels 110A, 110B, 110T, etc.), thereby allowing the system 100 to perform better than conventional water heating solutions, such as water heaters placed in mechanical rooms.

[0058] In one embodiment, the system 100 includes a master controller with wireless communication options (e.g., WiFi, LTE, BMS). For example, in one embodiment, the master controller is integrated in or coupled to the power connection panel 130. As another example, in one embodiment, the master controller is integrated in or coupled to a heat pump control terminal box (e.g., heat pump control terminal box 260 or 270 in FIG. 3A) for controlling the array of heat pumps 120.

[0059] After the skid 110 is secured, the water connections 170 are connected to the building's water lines, the power connection panel 130 is connected to the building's main power supply, and the master controller is powered on to begin running and starting the system 100. The system 100 is a skid package that provides a plug-and-play drop-in hot water solution.

[0060] FIG. 1E illustrates a perspective view of the system 100 in FIG. 1A with more heat pumps 120, in one or more embodiments. In another embodiment, the array of heat pumps 120 includes six (6) heat pumps 120, instead of four (4) heat pumps 120. The heat pumps 120 are arranged and distributed across the exterior of the front side panel 110A of the skid 110, as shown in FIG. 1E.

[0061] Any dimensions shown in FIGS. 1A-1B are provided as examples only; the dimensions, size, and / or thickness of the skid 110 and / or other components of the system 100 are not limited to the dimensions shown in these figures. In one embodiment, a height of the skid 110 is substantially about 103¼ inches, as shown in FIG. 1A. In one embodiment, a length of the skid 110 ranges from substantially about 144 inches to substantially about 149 inches, as shown in FIG. 1A. In one embodiment, a width of the skid 110 ranges from substantially about 75⅜ inches to substantially about 94 inches, as shown in FIG. 1B.

[0062] In one embodiment, the skid 110 includes a service access door (e.g., service access door 212 or 222 in FIG. 3B) providing a user (e.g., a service technician) with access to components inside the skid 110.

[0063] FIG. 2A illustrates a front view of an example storage tank 140, in one or more embodiments. FIG. 2B illustrates a side view of the storage tank 140 in FIG. 2A, in one or more embodiments. FIG. 2C illustrates a top view of the storage tank 140 in FIG. 2A, in one or more embodiments. In one embodiment, a storage tank 140 of a HPWH system 100 includes a plurality of thermowells 142 distributed along the tank 140, wherein each thermowell 142 is shaped to receive and maintain a temperature sensor 141 (FIG. 1C). For example, in one embodiment, the storage tank 140 includes four thermowells 142 spaced out vertically (e.g., about 14 inches) across the tank 140.

[0064] In one embodiment, the storage tank 140 includes the cold water inlet port 143 for receiving cold water, the heat pump return port 144 for receiving hot water from the heat pumps 120, the hot water outlet port 145 for supplying hot water from the tank 140, the heat pump supply port 146 for supplying cold water from the tank 140 to the heat pumps 120, and the temperature and pressure relief port 147 for relieving an excessive amount of pressure or heat in the tank 140. The storage tank 140 further includes a tank water inlet port 148 for receiving water from another storage tank 140 that is interconnected to the tank 140 (e.g., multiple storage tanks 140 interconnected / ganged together, as shown in FIG. 3C).

[0065] The storage tank 140 provides on demand supply for heat pumps 120. In one embodiment, the storage tank 140 stores water at 150° F. for higher effective volume.

[0066] A size of the storage tank 140 varies depending on water demand / usage of a building. For example, a size of the storage tank may be, but is not limited to, 175 gallons, 220 gallons, 275 gallons, 325 gallons, 450 gallons, or 500 gallons.

[0067] Any dimensions shown in FIGS. 2A-2B are provided as examples only; the dimensions, size, and / or thickness of the storage tank 140 are not limited to the dimensions shown in these figures. In one embodiment, spacing between the thermowells 142 is substantially about 14 inches, as shown in FIG. 2A. In one embodiment, spacing between the last / bottommost thermowell 142 and the heat pump supply port 146 is substantially about 21 inches, as shown in FIG. 2A. In one embodiment, spacing between the cold water inlet port 143 and the heat pump supply port 146 is substantially about 12⅞ inches, as shown in FIG. 2A. In one embodiment, a height of the storage tank 140 from its top to the heat pump supply port 146 is substantially about 75 inches, as shown in FIG. 2B. In one embodiment, spacing between the heat pump return port 144 and the heat pump supply port 146 is substantially about 64 inches, as shown in FIG. 2B.

[0068] In one embodiment, multiple skids (e.g., skids 210 and 220 in FIG. 3A) are combined to create a large-scale HPWH system (e.g., system 200 in FIG. 3A) scalable to any building size and / or building water demand / usage.

[0069] FIG. 3A illustrates a front view of another example compact, centralized, and modular heat pump water heater (HPWH) system 200, in one or more embodiments. FIG. 3B illustrates a top view of the system 200 in FIG. 3A, in one or more embodiments. FIG. 3C illustrates a schematic view of the system 200 in FIG. 3A, in one or more embodiments. As shown in FIGS. 3A-3C, all components of the system 200 are mounted onto or housed within two skids-a primary skid 210 and a secondary skid 220. In one embodiment, each skid 210, 220 is an enclosure comprising a steel frame (e.g., frame 50 in FIG. 1D) with removable insulated side panels (e.g., side panels 210A, 210B, 210C, 210T, 220A, 220B, 220C, 220T, etc.). The system 200 is fitted into the frames of the skids 210 and 220 and mounted onto the skids 210 and 220.

[0070] In one embodiment, the components of the system 200 that are mounted onto or housed within the primary skid 210 include, but are not limited to, the following: (1) a first array of heat pumps 120 for heating water, (2) a first power connection panel 230 for power landing, (3) a first stratified primary storage tank 140 (e.g., STORAGE TANK 1 in FIG. 3C) for storing water, (4) one swing tank 150 for maintaining a setpoint temperature (e.g., 120° F.) in a hot water recirculation loop 296 (FIG. 3C), (5) one expansion tank 160 for preventing excessive water pressure as the system 200 heats up water, (6) a plurality of water connections 250 for exchanging water with a building the system 200 is located at, (7) a plurality of piping connections 290 for drainage, (8) a first heat pump control terminal box 260 for controlling the first array of heat pumps 120, and (9) a plurality of inter-skid piping connections 280 for connecting with one or more components mounted onto or housed within the secondary skid 220.

[0071] In one embodiment, the components of the system 200 that are mounted onto or housed within the secondary skid 220 include, but are not limited to, the following: (1) a second array of heat pumps 120 for heating water, (2) a second power connection panel 240 for power landing, (3) at least a second stratified primary storage tank 140 and a third stratified primary storage tank 140 (e.g., STORAGE TANK 2 and STORAGE TANK 3 in FIG. 3C) for storing water, (4) a plurality of piping connections 295 for drainage, (5) a second heat pump control terminal box 270 for controlling the second array of heat pumps 120, and (6) a plurality of inter-skid piping connections 285 for connecting with one or more components mounted onto or housed within the primary skid 210.

[0072] As described in detail later herein, the system 200 is scalable using multiple storage tanks 140 across the skids 210 and 220 that are interconnected / ganged together.

[0073] In one embodiment, each heat pump 120 is a CO2 heat pump that uses CO2 as a refrigerant. In one embodiment, each heat pump 120 allows for hot water production even when ambient temperatures fall to −20° F. or below. In one embodiment, the first array of heat pumps 120 includes, but is not limited to, four (4) heat pumps 120 mounted onto an exterior of the primary skid 210 (e.g., arranged and distributed across an exterior of a front side panel 210A of the primary skid 210), and the second array of heat pumps 120 includes, but is not limited to, four (4) heat pumps 120 mounted onto an exterior of the secondary skid 220 (e.g., arranged and distributed across an exterior of a front side panel 220A of the secondary skid 220). In another embodiment, each array of heat pumps 120 includes a different number of heat pumps (e.g., the second array includes six (6) heat pumps 120, whereas the first array includes four (4) heat pumps 120, as shown in FIG. 3C).

[0074] In one embodiment, the second power connection panel 240 is mounted onto an exterior of the secondary skid 220 (e.g., on an exterior of a side panel of the secondary skid 220, such as a right side panel 220C, as shown in FIG. 3N).

[0075] As shown in FIG. 3C, in one embodiment, the first storage tank 140, the swing tank 150, and the expansion tank 160 are housed inside the primary skid 210. As further shown in FIG. 3C, the plurality of water connections 250 (FIGS. 3A-3B) include a hot water recirculation return 250A (e.g., a 1½ inch copper stub) for returning hot water to the system 200, a cold water inlet 250B (e.g., a 2 inch copper stub) for receiving cold water from the building, and a hot water outlet 250C (e.g., a 2 inch copper stub) for supplying hot water to the building.

[0076] In one embodiment, the second storage tank 140 (STORAGE TANK 2) in the secondary skid 220 includes a cold water inlet port 143 for receiving cold water from the cold water inlet 250B, via the inter-skid piping connections 280, 285. The second storage tank 140 includes a heat pump supply port 146 for supplying cold water stored (towards the bottom of the second storage tank 140) to: (1) the first array of heat pumps 120 on the primary skid 210, via the inter-skid piping connections 280, 285, for heating, and (2) the second array of heat pumps 120 on the secondary skid 220 for heating. Each heat pump 120 includes a cold water inlet 120A for drawing cold water from the second storage tank 140 which it then heats. Each heat pump 120 includes a hot water outlet 120B for supplying hot water to the first storage tank 140 (STORAGE TANK 1) in the primary skid 210 for storage (via the inter-skid piping connections 280, 285 for heat pumps on the secondary skid 220).

[0077] In one embodiment, the first storage tank 140 (STORAGE TANK 1) in the primary skid 210 includes a heat pump return port 144 for receiving hot water from the heat pumps 120 which it then stores. The first storage tank 140 includes a hot water outlet port 145 for supplying hot water stored (towards the top of the first storage tank 140) to the swing tank 150 in the primary skid 210.

[0078] In one embodiment, the second storage tank 140 (STORAGE TANK 2) in the secondary skid 220 includes a hot water outlet port 145 for supplying hot water stored in the second storage tank 140 to the third storage tank 140 (STORAGE TANK 3) in the secondary skid 220. The third storage tank 140 includes a tank water inlet port 148 for receiving water from the second storage tank 140. The third storage tank 140 includes a hot water outlet port 145 for supplying hot water stored in the third storage tank 140 to the first storage tank 140 (STORAGE TANK 1) in the primary skid 210, via the inter-skid piping connections 280, 285.

[0079] In one embodiment, the first storage tank 140 (STORAGE TANK 1) in the primary skid 210 includes a tank water inlet port 148 for receiving water from the third storage tank 140 in the secondary skid 220, via the inter-skid piping connections 280, 285.

[0080] In one embodiment, the swing tank 150 in the primary skid 210 includes a hot water inlet port 151 for receiving hot water (e.g., from the first storage tank 140 or the hot water recirculation loop 296) which it maintains the setpoint temperature of. The swing tank 150 includes a hot water outlet port 152 for supplying hot water (e.g., either to the building via the hot water outlet 250C or for recirculation via the hot water recirculation loop 296).

[0081] In one embodiment, the system 200 includes one or more temperature sensors 141 (i.e., temperature probes). For example, in one embodiment, each storage tank 140 includes at least two temperature sensors 141 disposed within thermowells 142 (FIG. 2A) of the storage tank 140, the swing tank 150 includes at least one temperature sensor 141, and multiple temperature sensors 141 are positioned along the hot water recirculation loop 296. In one embodiment, the system 200 includes one or more flow monitors to monitor pressure as water flows through the system 200.

[0082] In one embodiment, each tank 140, 150 includes a temperature and pressure relief port 147, 153 for relieving an excessive amount of pressure or heat in the tank 140, 150, thereby protecting the tank 140, 150 from any damage the excessive amount might have caused.

[0083] In one embodiment, the system 200 includes a master mixing valve 297, one or more balancing valves 298, one or more check valves 299, and a recirculation pump 294. Together with the swing tank 150, the master mixing valve 297 and the recirculation pump 294 help to maintain the setpoint temperature (i.e., target temperature) of the water in the hot water recirculation loop 296 to recover standby losses during periods of low hot water usage in the building. The swing tank 150 keeps primary storage of water in the storage tanks 140 separate from the hot water recirculation loop 296, and provides thermal storage to maintain the setpoint temperature. In one embodiment, the swing tank 150 includes an electrical element that maintains the setpoint temperature during extended periods of no water usage in the building. The swing tank 150 increases the efficiency of the heat pumps 120 by ensuring that the heat pumps 120 only heat cold water. Further, the swing tank 150 provides extra capacity beyond the capabilities of the heat pumps 120 for extreme draws (i.e., extreme water usage in the building).

[0084] Containing the system 200 within the skids 210 and 220 allow for easy delivery and installation of a large-scale water heating system, i.e., the skids 210 and 220 allow the system 200 to be easily transported and integrated. The skids 210 and 220 are delivered pre-engineered and pre-packaged to the site of the building when the skids 210 and 220 are ready to be installed.

[0085] FIG. 3D illustrates a top view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. FIG. 3E illustrates a front view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. FIG. 3F illustrates a right side view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, an exterior of a top side panel 210T of the primary skid 210 includes one or more lift points 211 (e.g., rigging eyelets with substantially about 1 inch through holes). For example, in one embodiment, each corner of the exterior of the top side panel 210T includes a lift point 211 positioned within proximity of the corner, as shown in FIG. 3D. The lift points 211 allow the entire primary skid 210 to be rigged such that a crane or a forklift can lift the primary skid 210 and drop-in the primary skid 210 into position. The primary skid 210 may be positioned onto a flat surface (such as on the rooftop of the building or on the ground adjacent to the building) and adjacent to the secondary skid 220.

[0086] FIG. 3G illustrates a left side view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, the first power connection panel 230 is mounted onto an exterior of the primary skid 210 (e.g., on an exterior of a side panel of the primary skid 210, such as a left side panel 210B). In one embodiment, the building water connections 250 include the hot water recirculation return 250A for returning hot water to the system 200, the cold water inlet 250B for receiving cold water from the building, and the hot water outlet 250C for supplying hot water to the building.

[0087] FIG. 3H illustrates a front view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, the piping connections 290 include, but are not limited to, the following: a heat pump condensate drain 290B (e.g., a ½ inch PVC stub) for drainage of condensation from the first array of heat pumps 120 on the primary skid 210, and tank temperature and pressure drains 290A and 290C (e.g., ¾ inch copper stubs) for drainage of any water leaks from each tank 140, 150 (FIG. 3C) in the primary skid 210 after all excess air escapes from the tank 140, 150 via its temperature and pressure relief port 147, 153 (FIG. 3C).

[0088] FIG. 3I illustrates a right side view of the primary skid 210 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, the first heat pump control terminal box 260 is mounted onto an exterior of the primary skid 210 (e.g., on an exterior of a side panel of the primary skid 210, such as a right side panel 210C). In one embodiment, the inter-skid piping connections 280 include a first heat pump manifold connection 280A (e.g., a 1 inch Female National Pipe Tapered (FNPT) union) for cold water, a second heat pump manifold connection 280B (e.g., a 1 inch FNPT union) for hot water, a cold water supply connection 280C (e.g., from the cold water inlet 250B) (e.g., a 2 inch FNPT union) to the secondary skid 220, and a storage tank mid-array connection 280D (e.g., for interconnecting the first storage tank 140 in the primary skid 210 with the third storage tank 140 in the secondary skid 220) (e.g., a 2 inch FNPT union).

[0089] Any dimensions shown in FIGS. 3D-3E and 3G-3I are provided as examples only; the dimensions, size, and / or thickness of the skid 210, water connections 250, piping connections 290, inter-skid piping connections 280, and / or other components of the system 200 are not limited to the dimensions shown in these figures. In one embodiment, a height of the skid 210 is substantially about 103¼ inches, a length of the skid 210 ranges from substantially about 144 inches to substantially about 149 inches, and a width of the skid 210 ranges from substantially about 75⅜ inches to substantially about 94 inches, as shown in FIGS. 3D-3E.

[0090] In one embodiment, vertical spacing between the water connections 250 and the flat surface / ground is substantially about 7½ inches, horizontal spacing between the hot water recirculation return 250A and the cold water inlet 250B is substantially about 6½ inches, horizontal spacing between the cold water inlet 250B and the hot water outlet 250C is substantially about 8¼ inches, and horizontal spacing between the hot water outlet 250C and a corner base plate 212A is substantially about 14 inches, as shown in FIG. 3G.

[0091] In one embodiment, vertical spacing between the piping connections 290 and the flat surface / ground is substantially about 9 inches, horizontal spacing between the tank temperature and pressure drain 290A and the heat pump condensate drain 290B is substantially about 6 inches, horizontal spacing between the heat pump condensate drain 290B and the tank temperature and pressure drain 290C is substantially about 5⅝ inches, and horizontal spacing between the tank temperature and pressure drain 290A and a corner base plate 212A is substantially about 63¼ inches, as shown in FIG. 3H.

[0092] In one embodiment, vertical spacing between a topmost row of the inter-skid piping connections 280 (e.g., heat pump manifold connections 280A and 280B) and the flat surface / ground is substantially about 86½ inches, vertical spacing between a bottommost row of the inter-skid piping connections 280 (e.g., cold water supply connection 280C, storage tank mid-array connection 280D) and the flat surface / ground is substantially about 78⅜ inches, horizontal spacing between the heat pump manifold connections 280A and 280B is substantially about 5½ inches, horizontal spacing between the cold water supply connection 280C and the storage tank mid-array connection 280D is substantially about 9½ inches, horizontal spacing between the first heat pump manifold connection 280A and a corner base plate 212A is substantially about 17⅜ inches, and horizontal spacing between the cold water supply connection 280C and the same corner base plate 212A is substantially about 17⅞ inches, as shown in FIG. 3I.

[0093] FIG. 3J illustrates a top view of the secondary skid 220 of the system 200 in FIG. 3A, in one or more embodiments. FIG. 3K illustrates a front view of the secondary skid 220 of the system 200 in FIG. 3A, in one or more embodiments. FIG. 3L illustrates a left side view of the secondary skid 220 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, an exterior of a top side panel 220T of the secondary skid 220 includes one or more lift points 221 (e.g., rigging eyelets with substantially about 1 inch through holes). For example, in one embodiment, each corner of the exterior of the top side panel 220T includes a lift point 221 positioned within proximity of the corner, as shown in FIG. 3J. The lift points 221 allow the entire secondary skid 220 to be rigged such that a crane or a forklift can lift the secondary skid 220 and drop-in the secondary skid 220 into position. The secondary skid 220 may be positioned onto a flat surface (such as on the rooftop of the building or on the ground adjacent to the building) and adjacent to the primary skid 210.

[0094] FIG. 3M illustrates a left side view of the secondary skid 220 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, the second heat pump control terminal box 270 is mounted onto an exterior of the secondary skid 220 (e.g., on an exterior of a side panel of the secondary skid 220, such as a left side panel 220B). In one embodiment, the inter-skid piping connections 285 include a first heat pump manifold connection 285A (e.g., a 1 inch FNPT union) for cold water, a second heat pump manifold connection 285B (e.g., a 1 inch FNPT union) for hot water, a cold water supply connection 285C (e.g., from the cold water inlet 250B in the primary skid 210) (e.g., a 2 inch FNPT union), and a storage tank mid-array connection 285D (e.g., for interconnecting the first storage tank 140 in the primary skid 210 with the third storage tank 140 in the secondary skid 220) (e.g., a 2 inch FNPT union).

[0095] FIG. 3N illustrates a front view of the secondary skid 220 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, the piping connections 295 include, but are not limited to, the following: a heat pump condensate drain 295B (e.g., a ½ inch PVC stub) for drainage of condensation from the second array of heat pumps 120 on the secondary skid 220, and tank temperature and pressure drains 295A and 295C (e.g., ¾ inch copper stubs) for drainage of any water leaks from each tank 140 (FIG. 3C) in the secondary skid 220 after all excess air escapes from the tank 140 via its temperature and pressure relief port 147 (FIG. 3C).

[0096] Any dimensions shown in FIGS. 3K-N are provided as examples only; the dimensions, size, and / or thickness of the skid 220, piping connections 295, inter-skid piping connections 285, and / or other components of the system 200 are not limited to the dimensions shown in these figures. In one embodiment, a height of the skid 220 is substantially about 103¼ inches, a length of the skid 220 ranges from substantially about 144 inches to substantially about 149 inches, and a width of the skid 220 ranges from substantially about 75⅜ inches to substantially about 94 inches, as shown in FIGS. 3K-3L.

[0097] In one embodiment, vertical spacing between a topmost row of the inter-skid piping connections 285 (e.g., heat pump manifold connections 285A and 285B) and the flat surface / ground is substantially about 86½ inches, vertical spacing between a bottommost row of the inter-skid piping connections 285 (e.g., cold water supply connection 285C, storage tank mid-array connection 285D) and the flat surface / ground is substantially about 78⅜ inches, horizontal spacing between the heat pump manifold connections 285A and 285B is substantially about 6 inches, horizontal spacing between the cold water supply connection 285C and the storage tank mid-array connection 285D is substantially about 9½ inches, horizontal spacing between the first heat pump manifold connection 285A and a corner base plate 212A is substantially about 17⅜ inches, and horizontal spacing between the cold water supply connection 285C and the same corner base plate 212A is substantially about 17⅞ inches, as shown in FIG. 3M.

[0098] In one embodiment, vertical spacing between the piping connections 295 and the flat surface / ground is substantially about 9 inches, horizontal spacing between the tank temperature and pressure drain 295A and the heat pump condensate drain 295B is substantially about 6 inches, horizontal spacing between the heat pump condensate drain 295B and the tank temperature and pressure drain 295C is substantially about 5⅝ inches, and horizontal spacing between the tank temperature and pressure drain 295A and a corner base plate 212A is substantially about 63¼ inches, as shown in FIG. 3N.

[0099] FIG. 3O illustrates an underside of each skid 210, 220 of the system 200 in FIG. 3A, in one or more embodiments. In one embodiment, one or more tie down points 212 extend from an underside 210U of each skid 210, 220 for securing the skid 210, 220 onto the surface. As shown in FIG. 3O, in one embodiment, the tie down points 212 include corner base plates 212A at corners of the underside 210U, side mounts 212B at a first pair of opposing sides of the underside 210U, and side mounts 212C at a second pair of opposing sides of the underside 210U. Each corner base plate 212A and each side mount 212B, 212C includes holes through which bolts / fasteners (e.g., 9 / 16 inch anchor bolts) are inserted to secure the skid 210, 220 to the flat surface / ground.

[0100] After the skids 210 and 220 are secured, the water connections 250 are connected to the building's water lines, the power connection panels 230 and 240 are connected to the building's main power supply, and the heat pump control terminal boxes 260 and 270 are powered on to begin running and starting the system 200. The system 200 is a plug-and-play drop-in hot water solution.

[0101] Any dimensions shown in FIG. 3O are provided as examples only; the dimensions, size, and / or thickness of the skids 210 and 220 and / or other components of the system 200 are not limited to the dimensions shown in these figures. In one embodiment, each corner base plate 212A is substantially about 10 inches by 10 inches, a length of each side mount 212B is substantially about 46 inches, and a length of each side mount 212C is substantially about 28 inches, as shown in FIG. 3O. In one embodiment, horizontal spacing between a corner base plate 212A and a side mount 212B along a width of a skid 210 / 220 is substantially about 4 11 / 16 inches, and horizontal spacing between a corner base plate 212A and a side mount 212C along a length of a skid 210 / 220 is substantially about 48 inches, as shown in FIG. 3O.

[0102] In one embodiment, each skid 210, 220 is a fully insulated enclosure (i.e., the steel frame of the skid 210 includes insulated side panels 210A, 210B, 210C, 210T, etc.; the steel frame of the skid 220 includes insulated side panels 220A, 220B, 220C, 220T, etc.), thereby allowing the system 200 to perform better than water heaters placed in mechanical rooms.

[0103] In one embodiment, the system 200 includes a master controller integrated in or coupled to the first heat pump control terminal box 260. In one embodiment, the master controller is integrated with wireless communication options (e.g., WiFi, LTE, BMS).

[0104] Table 1 below provides example technical specifications for the system 200.TABLE 1PERFORMANCETOTAL HEAT PUMP CAPACITY [MBH]123TOTAL PRIMARY STORAGE VOLUME (GAL.)660MAX. DAILY HW OUTPUT (GAL. / DAY)*2,560MAX. DAILY RUNTIME (hr. / DAY)16NOMINAL HOURLY HOT WATER OUTPUT (GAL. / hr.)160RECIRCULATION PUMP OUTPUT (HP)½RECIRC. PUMP MAX. HEAD (FT.-H2O)55NOMINAL OPERATING SOUND PRESSURE LEVEL (dBA)40MAX. SYSTEM WATER PRESSURE (PSI)94ELECTRICALPRIMARYSECONDARYSKID PANELSKID PANELSUPPLY208 V / 3208 V / 3Ph / 60 HzPh / 60 HzTOTAL24.78.0CONNECTEDLOAD [kVA]FULL LOAD68.422.0AMPS [A]MINIMUM89.432.1CIRCUITAMPACITY [A]MAXIMUM9035OVERCURRENTPROTECTION [A]WEIGHT (APPROX.)PRIMARY / SECONDARY DRY (LBS.)5,500 / 4,900PRIMARY / SECONDARY WETTED (LBS.)8,400 / 8,700COMPONENTS(8) HEAT PUMPREFRIGERANT TYPE: R-744 (CO2)WATER HEATERSTOTAL CHARGE: 203 OZ.AIRFLOW (CFM): 4,800EXTERNAL STATIC PRESSURE (IN.-H2O): 0(3) 220 GAL. STORAGE TANKS(1) SWING TANK, 119 GAL. / 12 kW(2) EXPANSION TANKS, 45 GAL. / 30 GAL. ACCEPTANCE(1) ELECTRONIC1 IN. BODY: 3-94 GPMMIXING VALVERECOMMENDED FLOW RANGE(1) RECIRCULATION PUMP, ECM(1) HEAT PUMP STAGING CONTROLLER(1) INCOMING COLD WATER WYE-STRAINER, 20-MESHCONSTRUCTIONENCLOSURER8 INSULATIONPANELSPOWDER COAT FINISHPIPINGTYPE K COPPERDIELECTRIC CONNECTIONSWHERE REQUIRED1-½″ INSULATION, MIN.R-VALUE: 8.6UL508A - LISTEDPOWER DISTRIBUTIONELECTRICAL PANELSEQUIPMENT / STAGING CONTROLLERPAINTED CARBON STEEL FRAMEELECTRICAL DISTRIBUTION PANEL WITH MAIN DISCONNECTINDIVIDUAL COMPONENT DISCONNECTS ON HEAT PUMPS AND SWING TANKHEAT PUMPS MOUNTED WITH VIBRATION ISOLATORSINSULATED BASE NOT PROVIDED BELOW STORAGE AND SWING TANKSREVERSE-RETURN HEAT PUMP MANIFOLD PIPING CONFIGURATIONINDIVIDUAL HEAT PUMP SOLATION, DRAIN AND CHECK VALVE*100° F. LIFT AND 16 hr. / DAY MAX. COMPRESSOR RUNTIME

[0105] In one embodiment, each skid 210, 220 includes a service access door 212 (FIG. 3B), 222 (FIG. 3B) providing a user (e.g., a service technician) with access to components inside the skid 210, 220.

[0106] Each HPWH system 100, 200 is a modular, pre-engineered, and pre-fabricated all-in-one centralized heat pump water heating system that is designed to integrate primary water heating and temperature maintenance, heat pumps, power landing, and controls all within a single, compact, one-piece or two-piece delivery unit. Each HPWH system 100, 200 is ready to operate after an installer plugs-and-plays the system 100 or 200 with an on-site's (e.g., a multi-family residential building) power and water connections. Utilizing heat pumps and stratified storage tanks, this plug-and-play approach greatly simplifies installation and addresses space constraints in various settings (e.g., urban settings where space is at a premium). The components of each system 100, 200 can be installed and started-up in as little as a day, thereby shortening the length of time it takes to custom design and build equivalent systems from months to a single day.

[0107] In one embodiment, each modular HPWH system 100, 200 is a pre-manufactured drop-in, central heat pump plant that uses CO2 as a refrigerant. Each modular system 100, 200 is ozone-friendly and does not contribute to global warming. Each modular system 100, 200 is designed and fabricated off-site, then delivered when needed. After each skid of the modular system 100 or 200 is physically secured on-site, the only connections required are mains power and the following water connections: cold water in, hot supply water, and recirculation.

[0108] In one embodiment, modular HPWH systems of different sizes and / or configurations than the modular systems 100 and 200 shown in FIGS. 1A-1C and 3A-3O are provided. Each modular HPWH system of a particular size is a complete central heat pump water heater and includes all heat pumps, tanks, pumps, controls, power panel, mixing station, piping, insulation, all housed in a seismic rated steel frame with powder coat finish that is enclosed in an insulated enclosure made of powder coated aluminum panels with integrated rigid R-8 insulation (i.e., a skid). Each skid of a modular system can be lifted by a forklift or craned in place. Sizes of each skid of a modular system are determined by a combination of heat pump capacity and water storage. These combinations match up to typical residential building loads. Engineers can review building load sizes by common industry sizing tools and select a skid to match the building load. Multiple skids can be used in zones on a single building to reach larger loads.

[0109] In one embodiment, each skid of a modular system is to be mounted on an elevated concrete pad or other suitable location. Once located, the skid is to be anchored according to a provided Installation, Operation, and Maintenance (IOM) manual.

[0110] Skids contain a power connection panel for the electrical supply to the building as well as building plumbing / water connections consisting of hot water supply to building, cold water make-up from building, and recirculation return from building.

[0111] At least one skid of a modular system has a power connection panel which requires external connection. For example, a skid may require 208V / 3 Ph / 60 Hz consisting of five wires: Lines A, B, C, Ground, and Neutral. Wire gauge and other details are to be determined by an installer based on NEC and local code requirements. Upstream overcurrent protection (e.g., building circuit breaker) is to be verified not to exceed the Maximum Overcurrent Protection (MOCP) listed on the nameplate of the distribution panel. As another example, each of the skid 210, 220 has a heat pump control terminal box 260, 270 with all required control wiring terminated-this box will need a bridge wiring connection to allow inter-skid communication and controls. Wiring and conduit requirements will conform with NEC and local codes.

[0112] In one embodiment, each modular HPWH system 100, 200 includes a staging controller that has primary enable / disable capability via its local user interface with secondary capability via Building Management System (BMS) command. When enabled, the controller will operate under its own internal controls to stage heat pumps and monitor for alarm conditions. The controller's Enable / Disable is stored in the retained memory to allow the modular system 100 or 200 to automatically restart after a building power failure. To prevent the controller from calling heat pumps to start after a power cycle, place it in Off mode before restarting. The controller shall monitor the Tank Temperature and HPWH Inlet water temperature to determine call for heating. The controller shall employ minimum On, Off, and Consecutive Start safety timers to prevent undesired heat pump cycling. The controller shall balance unit run times by starting the units in order of lowest operating hours. In the event that a unit is replaced, the run hour counters can be individually reset. The controller will monitor outdoor air temperature via its Outside Air temperature sensor and activate freeze protection when the temperature drops below −20° F. In the event a heat pump experiences a critical fault, it will report this to the controller via its alarm contact closure.

[0113] Each skid of a modular system is pneumatically pressure-tested prior to leaving the factory, but some leaks may still be present. Fittings have been located throughout each skid to aid in air purging. Each outlet (upper connection) of a heat pump has a ball / drain combination valve to allow a garden hose connection to flush the internals of the heat pump. Mixing valve outlet also contains a ball / drain combination valve with garden hose outlet. Recirculation pump outlet flange has an integrated isolation / drain valve with garden hose outlet for pump priming. Each storage tank and swing tank has an automated air release valve.

[0114] In another embodiment, each modular HPWH system 100, 200 uses another low GWP (Global Warming Potential) refrigerant other than CO2 that could offer similar benefits but with different operational characteristics or cost structures.

[0115] In another embodiment, modular systems of different modular configurations that offer more customizable options in terms of size, capacity, and component layout are provided to cater to a broader range of building types or specific industry needs.

[0116] In another embodiment, a design can be made with PCM (Phase Change Material) or alternative thermal storage solutions. This might include advanced sensible heat storage materials or other types of phase change materials with different melting points and thermal properties.

[0117] In another embodiment, a modular system designed to integrate more seamlessly with renewable energy sources like solar or wind power is provided, optimizing energy use for heating water during peak production times.

[0118] In another embodiment, a modular system provided is enhanced with more advanced IoT (Internet of Things) capabilities, AI-based predictive maintenance, and remote monitoring. This would offer improved user experience, energy management, and maintenance scheduling.

[0119] In another embodiment, a modular system provided is maintenance-friendly, with easily replaceable components or designs that allow for future technological upgrades without replacing the entire system.

[0120] In another embodiment, a modular system provided is manufactured using alternative manufacturing techniques or materials that reduce the overall cost of the system without significantly impacting performance.

[0121] In another embodiment, a modular system provided has a more user-friendly interface (e.g., with touchscreen controls or more intuitive settings) to appeal to users who prioritize ease of use.

[0122] References in the claims to an element in the singular is not intended to mean “one and only” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described exemplary embodiment that are currently known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the present claims. No claim element herein is to be construed under the provisions of 35 U.S.C. section 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for.”

[0123] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0124] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the embodiments has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention.

[0125] Though the embodiments have been described with reference to certain versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

Claims

1. A compact and centralized heat pump water heater system comprising:a modular skid including:a stratified primary storage tank for storing cold water and hot water, wherein the storage tank is disposed inside the skid; andan array of heat pumps for heating the cold water into the hot water, wherein the heat pumps are mounted onto an exterior of the skid; anda master controller for controlling the system;wherein the hot water is supplied to a building structure.

2. The system of claim 1, wherein the building structure is one of a multi-family residential building, an office, a factory, an industrial space, or a commercial space.

3. The system of claim 1, wherein the modular skid further includes:a recirculation loop; anda swing tank, a master mixing valve, and a recirculation pump for maintaining a target temperature of the hot water in the recirculation loop.

4. The system of claim 1, wherein the modular skid further includes:a plurality of water connections for connecting to a water supply of the building structure; anda power connection panel for connecting to a power supply of the building structure.

5. The system of claim 4, wherein the system is delivered pre-engineered and pre-manufactured to a site of the building structure for installation.

6. The system of claim 5, wherein the installation comprises:connecting the water connections to the water supply of the building structure;connecting the power connection panel to the power supply of the building structure; andpowering on the master controller to start and run the system.

7. The system of claim 1, wherein the modular skid further includes:a plurality of piping connections for drainage.

8. The system of claim 1, wherein each heat pump uses carbon dioxide as a refrigerant.

9. The system of claim 1, where the array comprises an even number of heat pumps.

10. A compact and centralized heat pump water heater system comprising:a modular primary skid including:a first stratified storage tank for storing cold water and hot water, wherein the first stratified storage tank is disposed inside the primary skid; anda first array of heat pumps for heating the cold water into the hot water, wherein the first array of heat pumps are mounted onto an exterior of the primary skid;a modular secondary skid including:at least one additional stratified storage tank for storing the cold water and the hot water, wherein the at least one additional stratified storage tank is disposed inside the secondary skid; anda second array of heat pumps for heating the cold water into the hot water, wherein the second array of heat pumps are mounted onto an exterior of the secondary skid; anda master controller for controlling the system;wherein the hot water is supplied to a building structure.

11. The system of claim 10, wherein the building structure is one of a multi-family residential building, an office, a factory, an industrial space, or a commercial space.

12. The system of claim 10, wherein the primary skid further includes:a recirculation loop; anda swing tank, a master mixing valve, and a recirculation pump for maintaining a target temperature of the hot water in the recirculation loop.

13. The system of claim 10, wherein:the primary skid further includes:a plurality of water connections for connecting to a water supply of the building structure; anda first power connection panel for connecting to a power supply of the building structure; andthe secondary skid further includes:a second power connection panel for connecting to the power supply of the building structure.

14. The system of claim 13, wherein the system is delivered pre-engineered and pre-manufactured to a site of the building structure for installation.

15. The system of claim 14, wherein the installation comprises:connecting the water connections to the water supply of the building structure;connecting the first power connection panel and the second power connection panel to the power supply of the building structure; andpowering on the master controller to start and run the system.

16. The system of claim 10, wherein each primary and secondary skid further includes:a plurality of piping connections for drainage.

17. The system of claim 10, wherein each heat pump uses carbon dioxide as a refrigerant.

18. The system of claim 10, where each array comprises an even number of heat pumps.

19. The system of claim 10, wherein the first array comprises a different number of heat pumps than the second array.

20. The system of claim 10, wherein each primary and secondary skid further includes:a plurality of inter-skid piping connections for interconnecting the primary skid with the secondary skid.

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