AU2010227022A1 - A Fluid Recirculation Method and Device - Google Patents

Abstract

A method is provided for reducing water wastage in a water supply system by re circulating cold water that reaches a water outlet until such time that the water reaching said water outlet is at a predetermined temperature. Also a control means 5 (1) is provided for a device that increases the pressure of diverted water from a fluid-saving device so that it can be introduced back into a closed system. The control means (1) comprising a housing (2) having a first chamber (7) with an inlet (3) that is connectable to a source of redirected fluid, a second chamber (8) with an aperture (5) that is open to the atmosphere, and a third chamber (9) with an outlet 10 (4) that is connectable to a pressure increasing means. The control means (1) also comprises a piston (6) received within the housing (2). The piston (6) is moveable between an open position, which permits fluid communication between the first (7) and third (9) chambers, and a default closed position, which prevents fluid communication between the first (7) and third (9) chambers. The control means (1) 15 further comprises switch means (13, 14, 15, 16) for activating a pressure increasing means when the piston (6) is in the open position and deactivating said pressure increasing means when the piston (6) is in the closed position. Sheet 2 of 3 co C-4 co co LO cn co cn co co

Description

ORIGINAL Australia Patents Act 1990 Complete Specification for the Invention Entitled A FLUID RECIRCULATION METHOD AND DEVICE The invention is described in the following statement: 2 A FLUID RECIRCULATION METHOD AND DEVICE The present invention relates to water-saving devices and in particular to devices for introducing diverted water back into the water supply system of a building. 5 The conservation of clean water is of increasing concern. This concern is most clearly felt in areas of the World such as Africa, the Middle East and Australia, where the environment can be harsh. However, even in countries with a plentiful supply of water, domestic water must be stored in reservoirs and it must be treated to be fit for human consumption. 10 In areas where water is in plentiful supply, the levels of wasted water are high. On an individual level waste may not be huge, but the accumulated wasted water from all the users represents a large amount of clean water that is simply fed down the drain. One particular source of waste occurs every morning when it takes time for 15 the hot water to come through the water pipes to the hot tap. As a result the first user at each tap usually turns on the tap until the water runs hot. In this way, in any one city on any one morning, millions of litres of clean water can be wasted. Various solutions to the above problem have be put forward. However, all of the offered solutions have disadvantages, which have prevented their wide-scale 20 adoption. Canadian Patent No 2252350 describes a water supply system wherein water that is either too hot or too cold is prevented from exiting the system via an open tap. The system prevents the wastage of water discussed above by diverting water of the wrong temperature back around the system until the water reaching 25 the chosen tap is the correct temperature.

3 One of the main problems with the above system is that it requires a complete re-plumbing of the water supply system, including the pipes and taps. This may not be a huge issue with new build properties, but it can be prohibitive in older properties, where the total water savings by the individual property do not 5 warrant the plumbing costs. Furthermore, the nature of the valve system used in Canadian Patent No 2252350 is such that new bathroom furniture (e.g. taps, shower-heads, etc.) must be fitted also. This further increases the cost involved as well as limiting the level of aesthetic choice available to the owners of the property. 10 Another solution is offered by the "demand system", this system uses the same principal as is used for central heating, it has the hot water being constantly pumped around the water pipes, so when a tap is opened the passing hot water is there ready for use, this system requires quite an alteration to the plumbing, also needs a supply of electricity for the pump and switches and a water pump that is 15 expensive to buy and run, it also needs the returned and cooled water to be constantly re-heated which is a very uneconomical operation, and is therefore both expensive to install and run, and uses large amounts of valuable energy to constantly re-heat the circulating water. The actual system is extremely expensive and the cost is not recoverable from saved water bills, so is in very little use, and 20 rarely seen on the market. US Patent No 4554688 is an example of this form of water supply system. US Patent No 5165456 describes a more basic solution to the above mentioned problem with the previously wasted water being diverted to a portable water tank. Whilst such invention provides a solution to the above problem 25 without the disadvantages of the Canadian patent, the invention is impractical and 4 intrusive. The constant need for the user to lift and move the water storage tank would inevitably lead to the system being abandoned. International PCT Application No. AU2004/000415 discloses a water recovery system that addresses the above identified problem by providing a valve 5 assembly that can be fitted into the plumbing upstream of a tap outlet. The valve assembly ensures that only water that is above a predetermined temperature reaches the tap for discharge. The water that is not above the predetermined temperature is re-circulated back around the water system. The valve assembly is activated by a drop in water pressure at the tap outlet, which occurs when the tap is 10 turned on. This avoids the need for any sort of mechanical connection between the valve assembly and the tap outlet, as was described in UK Application No. 0520317.9. Although PCT/AU2004/000415 provides an effective solution to the above identified problems the disclosed valve assembly requires expensive and 15 sometimes unreliable components. The use of large ceramic components for example, which require a high level of precision, means that the cost of manufacturing the valve assembly can prohibitive. Also the use of the sometimes unreliable diaphragm in the valve assembly can lead to additional repair costs for the user. 20 There are now a number of thermal diverter valves being developed to save the water that has cooled in the hot tap supply pipes and is generally run off down the drain, any example of which is International PCT application PCT/GB2008/002989, which is also in the name of the current inventor. All of these systems divert the cooled water to outside storage, or an 25 internal tank. Which then has to use a pump with the associated wiring to the 5 location of the storage vessel, which would often be some distance away, and not in a convenient position, for where the saved water is needed for reuse, and the user has to be constantly vigilant to prevent the storage vessel/s from overflowing and causing possible expensive flood damage to property etc. 5 There have also been a few return systems that lower the pressure in the cold water line, using a standard pressure reducing valve, and linking the saved return water from the hot tap supply pipe, directly to the cold tap supply pipe. In this way the saved 'slug' of water can be fed directly into the cold water line due to the created 'pressure gradient'. 10 In situations where a cold outlet open is not open all of the time, a pressure resistant storage/accumulator tank needs to be installed, so that when any cold tap/outlet was opened the stored water would then be sent to the open outlet, by virtue of its pressure being higher than the cold line due to the pressure gradient, between the hot and cold supply lines. 15 This above approach, although quite effective, is illegal to use due to the formation of several very dangerous bacteria, such as salmonella and legionella, that breed in enclosed heated and cooled water pipes and containers, and naturally contravenes water regulations in virtually every country throughout the world, and storing heated and cooled water in pipes and containers, is known to be the cause 20 of a large number of deaths annually throughout the world, in many hospitals and institutions etc. In view of the above regulations it is obviously more desirable to re-introduce the 'slug' of saved water back into the upstream supply pipe to the water heater. However this has up to now been considered impossible, due to the fact that an 25 enclosed water system has an equal pressure throughout the system when the 6 system is closed (i.e. no outlets are open). At present it is not possible to return the 'slug' of saved water back into the supply side (upstream) of the water heater so it can be reheated and used again. The present invention provides a method of reducing water wastage in a 5 water supply system by re-circulating water that reaches a water outlet until such time that the water reaching said water outlet is at a predetermined temperature according to claim 1. In accordance with the method of reducing water wastage another aspect of the present invention provides a device that is intended to be used in concert with 10 those water-saving devices that prevent water leaving the water outlet (e.g. hot tap) of a water supply system until the water is at a predetermined temperature. The present invention thus provides a device according to claim 10, which may be used in accordance with the above method to re-introduce redirected fluid, and in particular water, back in to a closed fluid supply system. 15 Another aspect of the present invention provides a control means according to claim 3 for use in the above mentioned device. The control means of the device operate the means for increasing the pressure of the water that is diverted to it from, for example, a temperature sensitive diverter valve so that the water can be re-introduced into the water supply system down a pressure gradient. 20 Preferably the piston of the control means may be received within the housing so as to define a wall of the first chamber and a wall of the second chamber. Preferably the switching means of the control means may comprise a switch that is mechanically operated by the movement of the piston within the 25 housing. Further preferably the switching means may comprise a first magnet, 7 located on the piston, and a second magnet, located on the switch, and wherein the movement of the piston within the housing changes the relative positioning of the first and second magnets thereby generating a repulsive force that operates the switch. 5 Preferably the control means may further comprise resilient biasing means that default the piston to the closed position. Alternatively the piston may be suitably weighted so that the piston is biased towards the closed position by action on the force of gravity on the piston. Preferably the pressure increasing means of the device may comprise an 10 electric pump. It is appreciated that alternative mechanisms for increasing the water pressure may also be used without departing from the concept of the present invention. In addition to the above mentioned control means and device, the present invention also provides a water-saving system which comprises the device of the 15 present invention. The present invention provides a water-saving system according to claim 14. Preferably the conduit of the water-saving system may be connected so as to introduce the water into the system upstream of the water heating means. Alternatively the conduit of the water-saving system may be connected so 20 as to introduce the water into a storage tank which feeds back into the system downstream of all the drinking water outlets in the system. Further preferably the system may also comprise a non-return valve to prevent introduced water exiting the system via a drinking water outlet. The present invention will now be described with reference to the 25 drawings, wherein: 8 Figure 1 shows an exposed side view of the control means of the device of the present invention; Figure 2 shows a first preferred arrangement of the water supply system of the present invention; and 5 Figure 3 shows a second preferred arrangement of a water supply system of the present invention. It is appreciated that the mechanism for increasing the pressure of the water that is redirected to the device of the present invention so that it can be re introduced into a closed water supply may vary, with one example being an 10 electric pump. The present invention is therefore primarily directed at the control means that activate and deactivate the pressure increasing means of the device when water is redirected to the device from the type of water-saving device such as those mentioned in the background of invention. Figure 1 shows a preferred embodiment of the control means 1 of the 15 present invention. The control means I comprises a housing 2 that is preferably 'L' or 'T' shaped and has an inlet 3, an outlet 4 and an aperture 5. The inlet 3 is in alignment with the aperture 5 but not with the outlet 4. When the control means I is installed in a water supply system, which is essentially a closed system. As will be described later, the inlet 3 is connected in 20 fluid communication with diverted water outlet of a water-saving device so that when water below a pre-determined temperature is diverted from the water outlet (e.g. hot tap) it arrives at the control means I via the inlet 3. The outlet 4 is connected in fluid communication with the means for increasing the water pressure (not shown) so that, once activated, the means for 25 increasing the water pressure causes an increase in the water pressure of the 9 diverted water that enters control means via the inlet 3. One example of a suitable means for increasing the water pressure is a 12volt electric water pump, although other alternatives will become apparent on consideration of the present invention. The aperture 5, which is located in the wall of the housing that faces the 5 inlet 3 provides an egress from the closed system and is preferably open to the atmosphere. As will be explained further below, the provision of an egress from the closed system facilitates the initial movement of the piston within the control means. A piston 6 is provided within the housing 2 of the control means 1. In the 10 present embodiment the piston 6, which can slide within the housing 2, serves to help define three chambers within the housing 2. The first chamber 7 is provided between the inlet 3 and the piston 6. The second chamber 8 is provided between the piston 6 and the wall of the housing within which the aperture 5 is located. In the present embodiment it is important that the piston 6 moves in the 15 same plane as the inlet 3 and the aperture 5 so that the piston 6 can force the air out of the second chamber 8 and reduce its size. By reducing the size of the second chamber 8 the movement of the piston from the closed position to the open position within the housing is accommodated. Two '0' sealing rings are located in the skirt of the piston 6 to facilitate a 20 watertight seal that prevents any fluid communication between the first chamber 7 and the second chamber 8. A third chamber 9 is provided between the piston 6 and the outlet 4 of the control means. In the present embodiment the piston does not move in the same plane as the third chamber 9.

10 The piston 6 is provided with an internal conduit 11, which provides a route of fluid communication between the first chamber 7 and the third chamber 9 when the piston is in an open position. The shape of the conduit, which is dog legged, is such that the flow of water into the conduit applies a directional force to 5 the piston before it exits the conduit 11 into the third chamber 9, thus ensuring that the piston 6 stays in the open position for as long as water flows into the control means 1. The piston is in the open position when the inlet 3 and the outlet 4 of the control means are in fluid communication via the conduit 11 of the piston 6. When 10 the piston 6 is in the closed position the flow of water from the inlet 3 to the outlet is prevented by the piston body because the conduit outlet terminates at the wall of the housing 2 rather than in the third chamber 9. A spring 12 is provided to ensure that the piston 6 defaults towards the closed position where no water flows through the control means. The piston 6 is 15 provided with a sealing projection 6a that is positioned in line with the aperture 5 so that when the piston is in the open position the sealing projection can cover the aperture 5 and prevent fluid from leaking out of the control means I via the aperture 5. It will be appreciated that alternative arrangements of the piston within the 20 housing are possible provided the piston performs its primary role of controlling the fluid communication between the first and third chambers. Alternative means can be envisaged for biasing the piston 6 of the control means towards the closed position may be used. A micro switch 13 is provided adjacent to the housing 2. The micro switch 25 13 operates the means for increasing the water pressure (not shown) so as to turn it 11 on and off. The micro switch 13 is provided with an arm 14 that is pivotably mounted on the micro switch 13 so as to turn the switch on and off. A first magnet 15 is located at the end of the arm 14 and a second magnet 16 is located on the piston 6. The magnets 15 and 16 are oriented so that their 5 poles both point in the same direction. In this way the magnets attract one another when they are in offset from one another, but repel one another when they are forced into close proximity with one another. As the piston magnet 16 is not free to move away from the switch magnet 15, when the piston 6 is moved into the open position, it is the switch magnet 15 10 that is physically repelled. The repulsion of the switch magnet 15 operates the arm 14 thereby operating the micro switch 13. Alternative mechanisms can be envisaged for operating a switch to the means for increasing the water pressure when the piston moved. The operation of the control means 1 of Figure 1 will now be described in 15 more detail. The device of the present invention, of which the control means are in important part, is installed on the redirected (or saved) water line that is itself connected between a first junction with the main water supply system, which is provided by a water-saving apparatus, and a second junction with the main water supply system, which is the point where any diverted water is re-introduced in to 20 the main water supply system. The operation of the control means, and consequently the device, commences when a hot water outlet of the water supply system is opened. If the water is at or above (in the case of a hot tap) a predetermined temperature the water outlet will operate as normal and allow the water to pass through the 25 thermally actuated diverter valve of the previously mentioned water-saving 12 apparatus and exit the system. In the case where the water outlet is a hot tap, for example, any water arriving at the water outlet that is below the required temperature will be diverted to the water saving line by the thermally actuated diverter valve. 5 It is envisaged that a suitably calibrated thermally actuated diverter valve could be used to ensure the water exiting a cold outlet is at or below a predetermined temperature. It is the flow of this diverted water into the control means 1 that forces the piston 6 towards the open position wherein the diverted water can pass into the 10 third chamber 9 and out of the outlet 4. The movement of the piston 6 from the closed position to the open position forces the air out of the second chamber 8 via aperture 5. By allowing a preliminary flow out of the control means and closed system to atmosphere via the aperture 5 it is possible to create a flow in the diverted water line which causes the piston 6 to rapidly move from the closed 15 position to the open position thus bringing the piston magnet 16 and the switch magnet 15 into opposition with one another. The repulsive force created between the two magnets forces the switch magnet 15 and the arm 14 to which it is attached to move thus operating the micro switch and turning on an electric water pump. 20 Once the pump is switched on it will continue to pump the diverted water back into the main water supply system for as long as the water continues to be diverted by the thermal diverter valve. The flow of diverted water through the control means I via the conduit 11 ensures that the piston 6 remains in the open position. As long as the piston 6 remains in the open position the magnets continue 25 to repel one another and the micro switch stays switched on.

13 Once water at or above the pre-determined temperature arrives at the thermally activated diverter valve, the valve will operate to allow the water to exit the water outlet. As a result of the flow of water to the control means via the saved water line will eventually cease thus allowing the piston 6 to return to the closed 5 position under the action of the spring 12. As the piston returns to its default position it separates the piston magnet 16 and the switch magnet 15 thus allowing the arm 14 to move and switch off the micro switch 13. The water pump will then turn off. As the piston 6 moves back to the closed position it causes air to be drawn 10 into the second chamber 8 via the aperture 5. The slight delay in the deactivation of the water pump also creates a small vacuum in the saved water line. It has been discovered that this small vacuum in the saved water line assists the water flow at the subsequent tap opening when water is redirected. It is understood that this creates a very small initial flow cycle, 15 which helps some thermally activated diverter valves (such as the water-saving apparatus described in International patent application no. PCT/GB2008/002989) to rise and open their ports, thereby allowing diverted water to flow into the saved water line. The above described arrangement is such that, once a water outlet (e.g. a 20 hot tap) has been opened, the whole process of water saving fully automated and does not require any further action by the user. Thus once the device of the present invention is installed with a water-saving device, such as the one described in PCT/AU2004/000415, the whole process operates seamlessly. In alternative arrangement of the control means 1, the aperture 5 may feed 25 a water storage tank, which is preferably open to the atmosphere, rather than 14 simply venting directly to atmosphere. In this way any water that might leak around the piston 6 is captured. As already described, the '0' sealing rings 10 are provided to prevent the flow of water from the first chamber 7 into the second chamber 8. 5 As already described the control means forms part of a device for introducing redirected fluids, such as water, back into a closed system, such as the water supply system of a building for example. Figures 2 and 3 illustrate different system arrangements that utilise the control means and/or device of the present invention. 10 All of the systems shown in figures 2 and 3 have the standard components of a standard water supply system, which will be identified using the same reference numerals. Each of the figures show a water supply system with a water heater 20 which is fed by the mains water supply pipe 21. Once water from the mains water 15 supply pipe 21 enters the system it is prevented from returning by a non-return valve 22. A junction is provided after the non-return valve 22 where the mains water supply pipe splits into two, with one pipe carrying cold water (i.e. the cold water pipe 23) and one pipe feeding the water heater 20 (i.e. the heater supply pipe 24). 20 The cold water pipe 23 is directly connected to the various cold water outlets of the system, which include for example cold water taps 25, W.C. cistern 26, washing machine 27, and shower units 28a and b. The cold water taps 25, which are used as a source of drinking water, are isolated from the other cold water outlets mentioned above by a non-return valve 29. This prevents 25 contamination of the drinking water supply.

15 The water heater 20 supplies heated water to the hot water outlets via the hot water pipe 30. Typical hot water outlets supplied by the hot water pipe include hot water taps 31 and shower units 28a and 28b. As already described, in order to prevent the loss of cold water through the 5 hot water outlets 31 a water-saving device 32 is installed between the hot water pipe 30 and each hot water outlet 31. The diverted water out let of each water saving device 32 is connected to a saved water return pipe 33. In figure 2 the saved water return pipe 33 is provided with the control means I and an electric water pump 34. The water pump 34 is connected to the 10 control means I by wiring 35 so that it can be operated by the control means 1. As already described, once a flow of water is diverted from the water-saving apparatus 32 to the control means via the saved water return pipe 33 the control means 1 operates the electric water pump 34, which in turn increases the pressure of the water reaching the junction between the saved water return pipe 33 and the 15 heater supply pipe 24. It will be appreciated that because the pressure of the water in the saved water return pipe 33 is increased after the pump 34 the water will force its way back in to the heater supply pipe 24 thus allowing it to be heated for subsequent delivery to a hot water outlet 31. 20 In order to prevent the mains water in the heater supply pipe 24 from entering the saved water pipe 33 a non-return valve 36 is provided. Figure 3 shows an alternative system arrangement wherein, rather than using an electric water pump 34 to pump the water back in to heater supply pipe 24, the diverted water is pumped to a storage tank 37. The storage tank 37, which 25 is preferably a pressure storage tank, is then connected via a stored water return 16 pipe 38 to the cold water supply pipe 23 at junction after the non-return valve 29 so that back contamination of the drinking water supply is prevented. In retrofit or new build situations, so as to make the pipe work less intrusive, the storage tank 37 and the return pipe 38 could be fitted within the 5 confines of the roof space, alternatively the pipe 38 may be fitted under the floor of the dwelling. In order to prevent the storage tank 37 from being sucked empty, thus allowing air into the system, a very simple low level stop valve (such as a standard W/C cistern stop valve in reverse) may be incorporated. Thus, in anticipation of 10 the very unlikely event of the storage tank 37 becoming over full an overflow pipe with an incorporated pressure/none return valve may be fitted - similar to that used in all standard domestic water systems. The overflow could easily be routed to any outside water barrel, or water holding receptacle, with an attached warning not to be used for human consumption. 15 It is appreciated that, rather than re-introducing the water into the cold water supply pipe 23, the saved water from storage tank 37 could also be diverted directly to a W.C. cistern for flushing only. Although this is not considered the preferred arrangement, in some retrofit situations it could save on pipe routing and plumbing time. 20 Although the present invention is mainly described from the position of preventing cold water leaving a water supply system via a hot water outlet, it is envisaged that the present invention could also be employed in arrangements where hot water leaving a water supply system via a cold water outlet is to be prevented.

17 Although the present invention is described with reference to water and water supply systems, it is envisaged that the present invention may be usefully employed to save fluids in other fluid supply systems.

Claims (20)

1. A method of reducing water wastage in a water supply system by re circulating water that reaches a water outlet until such time that the water reaching said water outlet is at a predetermined temperature, said method 5 comprising: determining the temperature of the water supplying the water outlet and diverting the water to a recirculation conduit until the water reaches the predetermined temperature; directing the diverted water to pressure increasing means and 10 increasing the pressure of the diverted water above the pressure of the water supply system; re-introducing the diverted water back into the water supply system.

2. The method of claim 1, wherein the pressure increasing means are activated by control means that are actuated by the flow of the diverted 15 water.

3. A fluid actuated control means for a device for introducing redirected fluid, such as water, back into a closed system, said device having a pressure increasing means that increases the fluid pressure of the redirected fluid above the fluid pressure of the closed system so that the redirected fluid 20 can be re-introduced into said closed system; said control means comprising: a housing having a first chamber with an inlet connectable to a source of redirected fluid, a second chamber with an outlet that is open to 19 atmospheric pressure, and a third chamber with an outlet connectable to said pressure increasing means; a piston received within the housing, said piston being moveable from a default closed position to an open position by redirected fluid entering 5 the first chamber via the inlet, and whereby in the closed position fluid communication between the first and third chambers is prevented and in the open position fluid communication between the first and third chambers is permitted; and switch means for activating a pressure increasing means when the piston moves to the open position and 10 deactivating said pressure increasing means when the piston moves to the closed position.

4. The control means of claim 3, wherein the piston is received within the housing so as to define a wall of the first chamber and a wall of the second chamber. 15

5. The control means of claim 3 or 4, wherein the outlet of the second chamber vents to the atmosphere.

6. The control means of claim 3 or 4, wherein the outlet of the second chamber feeds into a storage tank.

7. The control means of any of claims 3 to 6, wherein the switch means 20 comprise a switch that is mechanically activated by the movement of the piston from the closed position to the open position.

8. The control means of claim 7, wherein the switch means comprise a first magnet located on the switch and a second magnet located on the piston 20 and whereby the movement of the piston to the open position forces the first and second magnets into close proximity which in turn operates the switch.

9. The control means of any of claims 3 to 8, further comprising resilient 5 biasing means that default the piston to the closed position.

10. A device for introducing redirected fluid, such as water, back into a closed system, said device having a pressure increasing means that increases the fluid pressure of the redirected fluid above the fluid pressure of the closed system so that the fluid can be re-introduced into said closed system; said 10 device having a control means that is actuated by the redirected fluid.

11. The device of claim 10, wherein the control means comprises: a housing having a first chamber with an inlet connectable to a source of redirected fluid, a second chamber with an outlet that is open to atmospheric pressure, and a third chamber with an outlet connectable to 15 said pressure increasing means; a piston received within the housing, said piston being moveable from a default closed position to an open position by redirected fluid entering the first chamber via the inlet, and whereby in the closed position fluid communication between the first and third chambers is prevented and 20 in the open position fluid communication between the first and third chambers is permitted; and switch means for activating a pressure increasing means when the piston moves to the open position and deactivating said pressure increasing means when the piston moves to the closed position. 21

12. The device of claim 10 or 11, wherein said control means is a control means according to any of claims 3 to 9.

13. The device of claim 10, 11 or 12, wherein the pressure increasing means comprises an electric pump. 5

14. A water supply system adapted to prevent the wastage of water by re circulating water that reaches the an water outlet until such time that the water reaching said water outlet is of a predetermined temperature, said system comprising: a device for introducing redirected fluid back into the water supply 10 system at a higher fluid pressure than the water supply system, said device having a control means that is actuated by the redirected fluid; a thermally actuated diverter valve which is located at a junction between a water supply, a water outlet and said device; and a conduit between the device and point at which the water is re 15 introduced into the system.

15. The system of claim 14, wherein said control means is the control means according to any of claims 3 to 9.

16. The system of claim 15, wherein the water is outlet is a hot water outlet and whereby any water that reaches the outlet that is below a 20 predetermined temperature is redirected.

17. The system of claim 15 or 16, wherein the conduit is arranged to re introduce the water into the system upstream of the hot water supply. 22

18. The system of claim 15 or 16, wherein the conduit is arranged to re introduce the water into the system downstream of all of the drinking water outlets in the system.

19. The system of claim 18, further comprising a non-return valve to prevent 5 re-introduced water exiting the system via a drinking water outlet.

20. The method of claim 1 or 2, wherein a device according to any of claim 10, 11, 12 or 13 is used to increase the pressure of the water.