WO2017035585A1

WO2017035585A1 - Modular system for heating fluids

Info

Publication number: WO2017035585A1
Application number: PCT/AU2016/050815
Authority: WO
Inventors: Phillip Graham SIDNEY
Original assignee: Quantum Energy Technologies Pty Limited
Priority date: 2015-09-01
Filing date: 2016-08-31
Publication date: 2017-03-09

Abstract

The invention provides a modular liquid heating system (100) including a tank module (200) and a compressor module (300). The system allows the tank module to be connected to the compressor module to provide a heat pump liquid heating system. Alternatively, the tank module may be operated as a stand-alone liquid heating system thereby providing a second mode of fluid heating.

Description

Modular System for Heating Fluids

Field of the Invention

[0001 ] The present invention relates generally to fluid heating systems.

[0002] The invention has been developed primarily for use as a fluid heating system and a method for heating water for domestic requirements and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use and may equally be used to heat other types of liquids and fluids in a variety of applications.

Background of the Invention

[0003] The following discussion of the prior art is intended to facilitate an understanding of the invention and to enable the advantages of it to be more fully understood. It should be appreciated, however, that any reference to prior art throughout the specification should not be construed as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.

[0004] Heat pumps systems utilise the same thermodynamic principles as a refrigerator to move thermal energy opposite to the direction of spontaneous heat flow by absorbing heat energy from a cold space and releasing it to a warmer one. Both refrigerators and heat pumps generally rely upon the circulation of a refrigerant around a circuit comprising compressor, a condenser, an expansion valve and an evaporator.

[0005] In the case of fluid heating heat pumps, the system absorbs heat from the ambient air to heat a fluid, such as water, in a tank. In general terms, heat energy is transferred from the ambient air to the refrigerant by the evaporator. This refrigerant gas is then compressed which causes the gas's temperature to be raised. This "hot" gas is passed through a tank mounted heat exchanger to transfer heat energy to the water inside the tank. Once the heat energy from the compressed gas has been transferred to the water in the tank, the gas becomes a liquid again, and then passes through an expansion device and back to the evaporator where the cycle is repeated.

[0006] In contrast to direct heating systems (such as an electrical resistance heater or gas fired water heaters) most of the heat energy for heating water comes from the external environment, so that only a fraction comes from electricity. Hence heat pump water heaters can, under favourable circumstances, provide coefficient of performance significantly greater than direct heating methods.

[0007] Despite the potential efficiency gains in operating a heat pump system, the additional complexity of the heat pumps may have disadvantages. One such disadvantage is associated with the comparatively large up-front investment of the system. Another relates to ongoing maintenance and serviceability of the system.

[0008] It is an object of the present invention to overcome or substantially ameliorate one or more of the deficiencies of the prior art, or at least to provide a useful alternative.

Summary of the Invention

[0009] Accordingly, in a first aspect the invention provides a liquid heating system including:

a liquid tank for storing liquid to be heated, the tank having a cold liquid inlet for connection to a liquid supply and a hot liquid outlet for connection to liquid distribution means;

a heating element in a heat exchanging relationship with the liquid to be heated; and

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

a compressor to circulate refrigerant fluid around the circuit; and a condenser having a refrigerant conduit in a heat exchanging relationship with the liquid to be heated;

the system further comprising:

a tank module including the liquid tank, the heating element and the condenser; and

a compressor module including the compressor and the evaporator;

wherein the fluid refrigerant circuit includes refrigerant supply and return lines fluidly connecting the compressor module and the condenser.

[0010] The invention also extends to the individual tank and compressor modules described above. [001 1 ] Accordingly, in a second aspect the invention provides a tank module for a liquid heating system, the system including:

a liquid tank for storing liquid to be heated, the tank including a cold liquid inlet for connection to a liquid supply and a hot liquid outlet for connection to liquid distribution means;

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

wherein the system comprises:

the tank module including the liquid tank, the heating element and the condenser; and

a compressor module including the compressor and the evaporator;

[0012] In another aspect the invention provides a compressor module for a liquid heating system, the system including:

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

wherein the system comprises:

a tank module including the liquid tank, the heating element and the condenser; and a compressor module including the compressor and the evaporator;

[0013] Preferably, the refrigerant lines are equipped with detachable coupling means for detachable fluid coupling of the tank module with the compressor module.

[0014] Preferably, the system further includes a control system for controlling the system and selectively activating a heat pump mode whereby the heat pump is activated to heat the fluid in the tank, or a heating element mode whereby the heating element is activated to heat the fluid in the tank.

[0015] Preferably, the control means is adapted to activate the heating element mode when the heat pump is inoperable.

[0016] Preferably, the control means is adapted to automatically activate the heating element mode when the compressor module is detached from the condenser.

[0017] Preferably, the control means includes switching means to selectively activate and deactivate the heating element mode.

[0018] Preferably, the switching means is trigged by connection of the compressor module to the tank module.

[0019] Preferably, each the detachable coupling means includes complementary inter- engaging coupling fittings.

[0020] Preferably, the coupling fittings are screw or bayonet fittings.

[0021 ] Preferably, the fittings include sealing means for sealing the line when coupling means are disconnected thereby preventing substantial loss of refrigerant fluid.

[0022] Preferably, the heating element is an electrical heating element and the tank module is adapted for connection to an electrical power supply. [0023] Preferably, the tank module includes an auxiliary electrical power outlet and the compressor module include electrical connection means for connection to the auxiliary electrical power outlet.

[0024] Preferably, the tank includes a tank wall formed from material having heat transfer properties; and the condenser refrigerant conduit includes a tube secured externally about the tank wall in heat-conductive contact with the external surface of the wall of the tank to transfer heat from condensation of refrigerant fluid in the tube through the wall to the liquid contained in the tank.

[0025] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are intended to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Brief Description of the Drawings

[0026] Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which:

[0027] Figure 1 is a pictorial view of a traditional electrically powered hot water system as is known in the art;

[0028] Figure 2 is a pictorial view of a tank module in accordance with an embodiment of the invention;

[0029] Figure 3 is a pictorial view of a modular liquid heating system including a tank module and a compressor module in accordance with an embodiment of the invention; and

[0030] Figure 4 is a pictorial view of fluid refrigerant line connector.

Preferred Embodiments of the Invention

[0031 ] Referring to the drawings, and particularly Figure 3, the invention provides a modular liquid heating system 100 including a tank module 200 and a compressor module 300. As is described later, the system allows the tank module to be connected to the compressor module to provide a heat pump liquid heating system. Alternatively, the tank module may be operated as a stand-alone liquid heating system thereby providing a second mode of fluid heating.

[0032] The liquid heating system shown in the drawings and described herein is a hot water system (HWS) used to heat and store liquid water for domestic use. As such, the system would generally be connected between a cold water supply, such as a mains supply or rain water capture tank, and a hot water distribution means, such as hot water plumbing network of a structure, building or domestic house. Of course the invention is not necessarily limited to applications heating water and may be configured to heat other fluids.

[0033] It will also be appreciated that herein the term "cold" and "hot" are only applied to distinguish between the relative temperatures of water (or fluid) which is unheated ("cold") and heated ("hot") by the fluid heating system.

[0034] Referring first to the tank module 200 shown in Figure 2, in many aspects, the module is similar to a traditional HWS 200' shown in Figure 1 . As such like features are provided with like reference numerals in Figure 1 and 2 for ease of comparison, other than the use of an apostrophe ( ) in Figure 1. For instance, both the traditional HWS 200' shown in Figure 1 and the tank module 200 of the invention shown in Figure 2, include a water tank 201 (and 201 ') for storing water. A cold or cool water inlet 202 is provided at a bottom portion of the tank and a hot water outlet 203 is disposed at a top portion of the tank, thereby allowing for connection of the tank to water distribution means (not shown).

[0035] The tank 201 includes a tank wall 204 which, as is shown in the figures, may be surrounded wholly or partly with a heat insulating material 205 to reduce heat loss from the tank. In this preferred embodiment, the tank wall 204 is formed of steel or stainless steel however in other embodiments, different materials including other metals, plastics and/or composites may also be used to form the tank wall. Furthermore, while the tank shown in the figures is generally cylindrical, it is not limited to this particular shape.

[0036] The system is substantially encased in a protective shell or shroud 206. In this case the shell is formed of a thin sheet metal; however, it will be appreciated that other materials may be used such as plastics and the like.

[0037] As seen in the circular cut away section of Figure 2, at least one heating means is provided in a heat exchanging relationship with the water to be heated. In this embodiment, the heating means is an electrical heating element 207 disposed within the tank 201 thereby in direct heat exchanging contact with the water in the tank. However, in other embodiments, the heating element 207 or elements may be located elsewhere within the tank module 200 whilst retaining a heat exchanging relationship with the water. For instance, the heating element 207 may be disposed outside the tank in contact with the tank wall so that heat is passed via the tank wall to the water within. Furthermore, other types of heating elements may supplement or replace the electrical element whether they are electrically powered or otherwise. For instance, suitable gas burner systems may be used in place of an electrical system with appropriate reconfiguration of the tank module, as would be appreciated by those skilled in the art. One other possible heating elements which may be used is an evacuated tube solar hot water heating system.

[0038] The electrical heating element 207 is adapted for connection to an electrical power supply, by way of electrical connection means provided on the tank module. The connection means as shown in Figure 2, is a power cable 208 having a detachable water resistant connector 209 enabling detachable connection to a complementary receiving socket of the power supply (not shown). Alternatively, the power cable may be "hard wired" to the power supply for instance, if required by safety regulations and/or building codes.

[0039] To monitor the water temperature in the tank and to switch on and off the heating element, the tank module is provided with a tank module controller 210 which includes at least one temperature sensor and switching unit. In a simple form the controller 210 is embodied in a thermostatic unit, however other control arrangements may also be used. An overflow outlet and a temperature/pressure relief valve may be provided to ensure the pressure inside the tank does not rise above predetermined limits. While shown in the drawings in a basic form, the tank module may incorporate other features or improvements known in the art of hot water systems.

[0040] In view of the above, it will be appreciated that the tank module 200 may be installed by means of the inlet and outlet (202 & 203) into a domestic plumbing network, electrically connected to an electrical power source and operated to provide hot water to hot water plumbing. In a heating element mode of operation, the tank module operates in the same way as any typical electrical heating element HWS 200' such as that shown in Figure 1 . That is to say, the heating element 207 is selected to be of sufficient output to adequately heat water in the tank for use as a normal HWS without alternative/auxiliary heating means being necessary. However, as will become apparent, the tank module 200 of the invention further includes features enabling it to be connected to a compressor module 300 and run in a heat pump mode whereby a heat pump is activated and used to heat the water in the tank in place of the heating element.

[0041 ] In this regard, turning again to Figure 2, the tank module of the invention is provided with a condenser 21 1 including a refrigerant conduit 212. The condenser 21 1 is disposed to place the conduit 212 in a heat exchanging relationship with the water to be heated and stored in the tank 201 . In the embodiment shown in Figure 2, the condenser conduit is formed by a tube, tightly wound around the outside of the tank 201 . Preferably, the condenser 21 1 configuration and tank 201 are in accordance with that described in WO 03/038342 which is incorporated herein by reference. However, other configurations of condenser may also be used without departing from the present invention. For instance, rather than indirectly heating the water through the tank wall, the condenser may be positioned substantially inside the tank, in direct contact with the water.

[0042] In any event, where the tank module 200 is used as a HWS independently, heating the water by means of heating element 207, the condenser 21 1 is generally functionless. As will be seen, it is only when connected to the compressor module, that the condenser 21 1 becomes a functioning component used to heat the water in the tank.

[0043] Returning to the drawings, Figure 3 shows the tank and compressor modules (200 & 300 respectively) connected together to form the heat pump water heating system 100. The heat pump relies on a typical refrigeration cycle to draw heat energy from the ambient atmosphere into a refrigerant, circulate the refrigerant to a condenser where the heat energy is absorbed by cold water in the tank. As such, the heat pump includes a fluid refrigerant circuit 301 fluidly connecting an evaporator 302 for absorbing heat energy from ambient conditions; a compressor 303 which circulates the refrigerant fluid around the circuit 301 ; the condenser 21 1 which is used to pass heat energy to the water in the tank 201 ; and an expansion valve 304 for controlling refrigerant flow to the evaporator 302. The evaporator 302 may include an evaporator fan 305. The fluid refrigerant which is sealed under pressure in the refrigerant circuit is preferably of a type regarded as environmentally friendly such as R290. However, other types of refrigerant may be used such as R134a, hydrocarbon refrigerants or C0₂ based refrigerants.

[0044] It will be appreciated that the device shown in the figures and described herein is limited to basic elements of a simple heat pump design utilising a typical single stage refrigeration cycle. However, the invention may be equally embodied in other heat pump designs employing modified refrigeration cycles as are known in the art. For instance, the heat pump shown herein may be replaced by a multiple stage heat pump and/or reverse Carnot cycle refrigeration system.

[0045] One aspect of the invention provides for the basic components of the heat pump to be distributed between the modules. That is to say, as previously noted, the condenser 21 1 is disposed along with the water tank 201 in the tank module 200, however the compressor 303 and the evaporator 302 are housed in the compressor module 300. Due to its relative size, the expansion valve 304 may be disposed in either module although preferably, in order to reduce the complexity and cost of the tank module 200, the expansion valve 304 is also located in the compressor module 300.

[0046] In order to fluidly connect the condenser 21 1 in the tank module 200 to the heat pump components in the compressor module 300, the system includes refrigerant supply and return lines (120 and 130 respectively) fluidly connecting the tank and compressor modules. The supply line 120 provides the condenser 21 1 with hot refrigerant fluid from the compressor module 300 and the return line 130 returns the refrigerant fluid once it has delivered heat to the water in the tank.

[0047] Furthermore, the refrigerant lines are each equipped with detachable coupling means 140 for detachable fluid coupling of the tank module 200 with said compressor module 300. In this regard, hot refrigerant fluid from an outlet of the supply line 120 on the compressor module is paired with a supply line inlet on a first end of the condenser conduit of the tank module. An outlet of the return line 130 on a second end of the condenser conduit is paired with and connectable to a return line inlet on the compressor module allowing the refrigerant fluid to be returned.

[0048] Accordingly, each supply/return line includes an inlet/outlet pair fluidly connectable by detachable coupling means 140. As can be seen with reference to Figure 4, the detachable coupling means 140 comprises a respective pair of complementary inter-engaging coupling fittings 141 and 142 secured to each inlet/outlet. In this way the supply and return lines may be connected and disconnected to enable the fluid refrigerant circuit to be readily joined and broken as required. Preferably, the coupling fittings are of the quick connector type suitable for joining fluid conduits under pressure, including screw-type connectors as shown in Figure 4, or alternatively, for instance, bayonet connectors or the like.

[0049] Each inlet and outlet also includes a sealing means for sealing the inlet/outlet when disconnected thereby preventing substantial refrigerant / pressure loss when the lines are disconnected. The sealing means are in the form of complementary shut off valves incorporated into each fitting (141 & 142). The shut off valves are of the self opening/closing type which automatically seal on disconnection and automatically open when the fittings are joined to thereby restore flow of refrigerant through the line. In particular, the valves shown in Figure 4 rely on differential pressure to seal each valve when disengaged from one another and mechanical interference to hold each valve open when the fittings are engaged. Other type of automatic or manual valves may be used, for instance simple manual tap valves or automatically operated electro-mechanically valves.

[0050] The compressor module 300 is provided with electrical connection means for connecting to a power supply. In particular, power is needed to run the compressor 303 and the evaporator fan 305, however other components of the compressor module may also require electrical power. As shown in the drawings, the electrical connection means is a power cable 320 provided with a detachable connector 321 enabling detachable connection to a complementary connector of a power supply. Most simply, the detachable connectors are of the plug and socket type.

[0051 ] In this embodiment, the tank module 200 is provided with an auxiliary power outlet 220 which may be used to provide power to the compressor module 300 from the tank module 200 thereby simplifying the electrical connection procedure. For instance, as previously noted, when installed without the compressor module 300, the tank module 300 is itself already connected to the power supply by means of a power cable and connector 209. However, when the compressor module 300 and tank module 200 are used together as a heat pump, the compressor module power cable 320 connector 321 , may be connected to the auxiliary power outlet 220 on the tank module 200 rather than directly to a power supply. It will be appreciated that this potentially makes for a faster plug in connection rather than having to hard wire into mains supply. Alternatively, it will be appreciated that an auxiliary outlet may be provided on the compressor unit so that the tank module is plugged into the compressor module. Further, it is also possible to configure each module with individual connection to the power supply. [0052] The power connectors including the auxiliary outlet are preferably of a type which are water-proof or highly water resistant.

[0053] The system further includes control means 400 for monitoring and controlling the heat pump, and components of the tank and compressor modules, including the compressor, evaporator, evaporator fan and expansion valve. The control means may utilise part or all of the tank module controller, including the water temperature sensor/s, switching unit/s and/or thermostat/s. Other sensors and switches are provided on the compressor module as required. In this regard, the control means is provided with a control link between the two modules so that the control of the modules may be integrated. As can be seen in the figures, in this embodiment the control link is established by means of a plug in type data cable 401 on each of the tank and compressor modules.

[0054] The control means 400 may operate the system in either a heat pump mode whereby the heat pump is activated to heat the fluid in the tank; or a heating element mode whereby the heating element is activated to heat the fluid in the tank.

[0055] With both modules connected together and the system functioning normally, the control means is configured to activate the heat pump mode thereby providing for heating of the water in the tank. In heat pump mode, the electrical heating element is automatically deactivated so that it is inoperable and provides no heating assistance. Deactivation (and reactivation) of the electrical heating mode is initiated by the control means which includes switching means. The switching means may be triggered by electrical connection of the two modules or by a physical or electrical switch which is thrown as the modules are connected.

[0056] In the event that the heat pump is rendered inoperable, malfunctions, requires maintenance or servicing, or the compressor module is disconnected from the tank module, emergency water heating can be achieved by activating the heating element mode. The tank module is then capable of providing hot water until such time as the heat pump is serviced, repaired or replaced at which time the electrical heating element is deactivated and the heat pump mode reactivated.

[0057] In this embodiment, the control system is configured to monitor and determine when and if the heat pump is rendered inoperable, malfunctions or the compressor module is disconnected from the tank module (either by disconnection of the data cable 401 or either of the supply/return detachable coupling means 140), and automatically initiate water heating by activating the heating element mode. Likewise, upon reconnection or repair of the compressor module, the control means will reactive heat pump mode and deactivate heating element mode.

[0058] Selective manual deactivation of the electrical heating element may also be provided, for instance by way of a manual switch, in addition to or as an alternative to automatic control described above. This provides for selective switching of the system between heating element and heat pump modes without disconnection of the modules.

[0059] In further embodiments, the control system is configured to activate the heating element mode according to particular monitored parameters of the heat pump and/or system. For instance, if and when the control system detects a system malfunction. Alternatively, in some embodiments, the system may activate the electrical heating means in the tank module while in heat pump mode to supplement the heat pump heating, for instance if ambient conditions prevent adequate heating via the heat pump for a particular selected heating temperature.

[0060] As can be seen in the drawings, the compressor module is designed to sit adjacent the tank module. Detachable mounting formations are provided on each module so that they may be physically secured together as a single unit thereby protecting the supply and return lines and electric connections from dislocation. Alternatively, the compressor module may be adapted to sit atop the tank module on support brackets. Still further, each module may be set spaced apart, for instance, on different sides of a wall whereby the tank module is installed inside a building and the compressor module outside with the various supply and electrical lines passing through the wall.

[0061 ] As will be appreciated, the selectable mode capability, and modular design provides distinct advantages over the prior art. Since the tank module may be used independently, it can be purchased and installed to provide a fully functioning HWS without the need to invest in a complete heat pump system. This makes the cost of the tank module generally comparable to the cost of a traditional HWS.

[0062] Of course the tank module has a significant advantage over a traditional HWS as it is readily upgradable to a heat pump type water heating system whereby the increased efficiency benefits of heat pump water heating may be realised. [0063] Together, the complete system also provides for enhanced reliability. That is to say, if the heat pump becomes inoperable, whether due to malfunction or to allow for onsite servicing of the heat pump components, the control means is adapted to deactivate the heat pump mode and activate the heating element mode. Furthermore, should the compressor module need to be removed for offsite servicing or replacement, it may be readily detached and sent for repair. In the meantime, the tank module will operate in heating element mode. Either way, the system of the invention will continue to provide a functioning HWS.

[0064] Clearly the system has significant advantages over traditional HWS particularly in applications where efficiency and reliability are important considerations. In hotels, resorts and hospitals for instance, energy costs, including running costs of hot water systems can be significant factors to profitability. Furthermore, providing reliable uninterrupted hot water to guests or patients is equally important particularly in remote locations where on site servicing may not be possible.

[0065] Another advantage provided by the modular nature of the system is that each module is significantly smaller in comparison to an equivalent integrated heat pump water heater. This difference in physical size and weight allows easier handling and of each module during shipping and installation.

[0066] In addition, the modular nature of the system allows some interconnectability between the tank module and different compressor modules. For instance, the compressor module may be swapped out for an upgraded unit, incorporating new features or greater heat capacity, or a different unit adapted to local ambient conditions. For instance changing a single stage heat pump for a multi stage heat pump.

[0067] Another significant advantage of the system is that by including the condenser 21 1 in the tank module, the comparative large volume of the tank and corresponding large surface area of the tank wall may be utilised as a heat exchanger thereby increasing heat transfer and heat transfer efficiency between the refrigerant fluid and the water in the tank. This configuration also allows the compressor module to be comparatively smaller in size. Furthermore, the water distribution circuit is not interrupted during connection or disconnection of the modules.

[0068] It will be appreciated that in these and other respects, the invention represents a practical and commercially significant improvement over the prior art. [0069] Unless specifically stated otherwise, it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

[0070] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0071 ] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0072] Similarly, it is to be noticed that the term coupled, when used in the claims, should not be interpreted as being limited to direct connections only. The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the expression a device A coupled to a device B should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. "Coupled" may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other.

[0073] Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1 . A liquid heating system including:

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

a compressor to circulate refrigerant fluid around said circuit; and

a condenser having a refrigerant conduit in a heat exchanging relationship with the liquid to be heated;

said system further comprising:

a compressor module including the compressor and the evaporator;

wherein said fluid refrigerant circuit includes refrigerant supply and return lines fluidly connecting the compressor module and the condenser.

2. A liquid heating system according to claim 1 further including a control system for controlling the system and selectively activating a heat pump mode whereby the heat pump is activated to heat the fluid in the tank, or a heating element mode whereby the heating element is activated to heat the fluid in the tank.

3. A liquid heating system according to claim 2 wherein said control means is adapted to activate said heating element mode when said heat pump is inoperable.

4. A liquid heating system according to claim 2 or 3 wherein said control means is adapted to automatically activate said heating element mode when said compressor module is detached from the condenser.

5. A liquid heating system according to claim 4 wherein said control means includes switching means to selectively activate and deactivate the heating element mode.

6. A liquid heating system according to claim 5 wherein said switching means is trigged by connection of the compressor module to the tank module.

7. A liquid heating system according to any one of the preceding claims wherein at least one of said refrigerant supply or return lines is equipped with detachable coupling means for detachable fluid coupling of the tank module with said compressor module.

8. A liquid heating system according to claim 7 wherein each said detachable coupling means includes complementary inter-engaging coupling fittings.

9. A liquid heating system according to claim 8 wherein said coupling fittings are screw or bayonet fittings.

10. A liquid heating system according to claim 8 or 9 wherein said fittings include sealing means for sealing said line when coupling means are disconnected thereby preventing substantial loss of refrigerant fluid.

1 1 . A liquid heating system according to any one of the preceding claims wherein said heating element is an electrical heating element and said tank module is adapted for connection to an electrical power supply.

12. A liquid heating system according to claim 1 1 wherein said tank module includes an auxiliary electrical power outlet and said compressor module include electrical connection means for connection to said auxiliary electrical power outlet.

13. A liquid heating system according to any one of the preceding claims wherein said tank includes a tank wall formed from material having heat transfer properties; and said condenser refrigerant conduit includes a tube secured externally about said tank wall in heat-conductive contact with the external surface of said wall of said tank to transfer heat from condensation of refrigerant fluid in said tube through said wall to the liquid contained in the tank.

14. A tank module for a liquid heating system, said system including:

a liquid tank for storing liquid to be heated, the tank including a cold liquid inlet for connection to a liquid supply and a hot liquid outlet for connection to liquid distribution means; a heating element in a heat exchanging relationship with the liquid to be heated; and

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

a compressor to circulate refrigerant fluid around said circuit; and a condenser having a refrigerant conduit in a heat exchanging relationship with the liquid to be heated;

wherein said system comprises:

a compressor module including the compressor and the evaporator;

15. A tank module for a liquid heating system according to claim 14 further including control means for operating the system in a heat pump mode whereby the heat pump is activated to heat the fluid in the tank or a heating element mode whereby the heating element is activated to heat the fluid in the tank.

16. A tank module for a liquid heating system according to claim 15 wherein said control means is adapted to activate said heating element mode when said heat pump is inoperable.

17. A tank module for a liquid heating system according to claim 15 or 16 wherein said control means is adapted to activate said heating element mode when said compressor module is detached from the condenser.

18. A tank module for a liquid heating system according to any one of claims 14 to 17 wherein said refrigerant lines are equipped with detachable coupling means for detachable fluid coupling of the tank module with said compressor module.

19. A tank module for a liquid heating system according to claim 18 wherein each said detachable coupling means includes complementary inter-engaging coupling fittings.

20. A tank module for a liquid heating system according to claim 19 wherein said fittings include sealing means for sealing said line when coupling means are disconnected thereby preventing substantial loss of refrigerant fluid.

21 . A tank module for a liquid heating system according to any one of claims 14 to 20 wherein said tank includes a tank wall formed from material having heat transfer properties; and said condenser refrigerant conduit includes a tube secured externally about said tank wall in heat-conductive contact with the external surface of said wall of said tank to transfer heat from condensation of refrigerant fluid in said tube through said wall to the liquid contained in the tank.

22. A tank module for a liquid heating system according to any one of claims 14 to 21 wherein said heating element is an electrical heating element and said tank module is adapted for connection to an electrical power supply.

23. A compressor module for a liquid heating system, said system including:

a heat pump including a fluid refrigerant circuit fluidly connecting:

an evaporator for absorbing heat energy from ambient conditions;

an expansion valve;

wherein said system comprises:

a compressor module including the compressor and the evaporator;

24. A compressor module for a liquid heating system according to claim 23 further including control means for operating the system in a heat pump mode whereby the heat pump is activated to heat the fluid in the tank or a heating element mode whereby the heating element is activated to heat the fluid in the tank.

25. A compressor module for a liquid heating system according to claim 24 wherein said control means is adapted to activate said heating element mode when said heat pump is inoperable.

26. A compressor module for a liquid heating system according to claim 24 or 25 wherein said control means is adapted to activate said heating element mode when said compressor module is detached from the condenser.

27. A compressor module for a liquid heating system according to any one of claims 23 to 26 wherein said refrigerant lines are equipped with detachable coupling means for detachable fluid coupling of the tank module with said compressor module.

28. A compressor module for a liquid heating system according to claim 27 wherein each said detachable coupling means includes complementary inter-engaging coupling fittings.

29. A compressor module for a liquid heating system according to claim 28 wherein said fittings include sealing means for sealing said line when coupling means are disconnected thereby preventing substantial loss of refrigerant fluid.

30. A compressor module for a liquid heating system according to any one of claims 23 to 29 wherein said tank includes a tank wall formed from material having heat transfer properties; and said condenser refrigerant conduit includes a tube secured externally about said tank wall in heat-conductive contact with the external surface of said wall of said tank to transfer heat from condensation of refrigerant fluid in said tube through said wall to the liquid contained in the tank.

31 . A compressor module for a liquid heating system according to any one of claims 23 to 30 wherein said heating element is an electrical heating element and said tank module is adapted for connection to an electrical power supply.