Methods and systems for heat exchangers

Abstract

A first fluid port (116) of a heat exchanger (100) is connected to a fluid source (302). The first fluid port is in fluid communication with a first fluid path (108) formed in an enclosed space between a first tube (102) and a second tube (104) of the heat exchanger (100) positioned in the first tube (102). The first fluid path (108) is accessible only by the first fluid port (116) and a second fluid port (118) of the heat exchanger also in fluid communication with the first fluid path (108). Fluid is restricted from exiting the first fluid path (108) via the second fluid port (118). The fluid source (302) is operated to deliver fluid via the first fluid port (116) while fluid is restricted from exiting the first fluid path (108) via the second fluid port (118). This causes the second tube (104) to deform towards a third tube (106) positioned in the second tube (104), thereby decreasing the separation between the first fluid path (108) and a second fluid path (114) defined by the third tube (106). The second tube (104) is more easily deformable than the first tube (102) and the third tube (106).

Description

[0001] METHODS AND SYSTEMS FOR HEAT EXCHANGERS

[0002] The present invention is directed towards methods and systems for heat exchangers, and in particular towards methods and systems for improving the efficiency of heat exchangers used to recover heat from waste water.

[0003] BACKGROUND

[0004] It is known to use heat exchangers to recover heat from waste water and in particular shower water.

[0005] The existing heat exchanger comprises a first tube, a second tube positioned within the first tube, and a third tube positioned within the second tube. A first fluid path is formed in an enclosed spaced between the first tube and the second tube. A second fluid path is formed through the third tube. The second fluid path is connected to a drain of a shower such that shower waste water flows along the second fluid path to a sewer. The first fluid path is connected between a cold water supply and the mixing valve and water heater for the shower. This arrangement enables waste heat to be transferred from the second fluid path to the first fluid path to warm the cold water flowing through the first fluid path. In this way, the water is pre-heated for delivery via the shower either directly via the mixing valve or subject to further heating by the water heater.

[0006] It is an object of the present disclosure to provide a method and system for heat exchangers that improves on the prior art whether expressly identified herein or otherwise.

[0007] SUMMARY

[0008] According to aspects of the present disclosure, there is provided a method and system as set forth in the accompanying independent claims. Other aspects of the disclosure are apparent from the dependent claims and the description which follows.

[0009] According to a first aspect of the disclosure, there is provided a method.

[0010] The method comprises connecting a first fluid port of a heat exchanger to a fluid source. The first fluid port is in fluid communication with a first fluid path formed in an enclosed space between a first tube of the heat exchanger and a second tube of the heat exchanger positioned in the first tube. The first fluid path is accessible only by the first fluid port and a second fluid port of the heat exchanger also in fluid communication with the first fluid path.

[0011] The method comprises restricting fluid from exiting the first fluid path via the second fluid port.

[0012] The method comprises operating the fluid source to deliver fluid via the first fluid port, while fluid is restricted from exiting the first fluid path via the second fluid port, so as to cause the second tube to deform towards a third tube positioned in the second tube, thereby decreasing the separation between the first fluid path and a second fluid path defined by the third tube.

[0013] The second tube is more easily deformable than the first tube and the third tube.

[0014] Advantageously, the fluid source is operated to deliver fluid via the first fluid port while fluid is restricted from exiting the first fluid path via the second fluid port. Here, restricted may mean that fluid is prevented from exiting the first fluid path entirely or that the fluid flow is limited but some fluid can still leave the first fluid path via the second fluid port. This means that fluid is able to enter the first fluid path but is restricted from exiting the first fluid path. Consequently, the pressure within the first fluid path is increased. The increase in pressure causes the second tube to deform into closer contact with the third tube. This decreases the separation between the first fluid path and the second fluid path. A reduction in the separation between the first fluid path and the second fluid path improves the efficiency of heat transfer between the first and second fluid paths.

[0015] The second tube may be brought into direct contact with the third tube. The second tube may conform to the outer surface of the third tube.

[0016] The fluid source may be operated to deliver fluid at a high pressure. The pressure may be at least 20 bar. The pressure may be at least 25 bar. The pressure may be at least 30 bar. The pressure may be at least 40 bar. The pressure may be less than 50 bar. The pressure may be less than 40 bar. The pressure may be less than 35 bar. The pressure may between 30 bar and 35 bar. It will be appreciated that the pressure used depends at least one the type of material used for the second tube and the thickness of the second tube. A thicker / harder material will require a higher pressure to cause the desired deformation as composed to a thinner / softer material.

[0017] Restricting fluid from exiting the first fluid path via the second fluid port may comprise manipulating a valve in fluid communication with the second fluid port. The valve may be positioned downstream of the second fluid port. The valve may be incorporated in an adapter connected to the second fluid port.

[0018] Prior to restricting fluid from exiting the first fluid path via the second fluid port, the method may comprise: enabling fluid to exit the first fluid path via the second fluid port; and operating the fluid source to deliver fluid via the first fluid port while fluid is enabled to exit the first fluid path via the second fluid port.

[0019] Advantageously, the fluid source is initially operated while the fluid flow from the second fluid port is not restricted so as to displace air in the first fluid path and fill the first fluid path with fluid. This improves the subsequent process of delivering fluid while fluid is restricted from exiting the first fluid path via the second fluid port.

[0020] The fluid may be delivered at a lower pressure prior to restricting fluid from exiting the first fluid path via the second fluid port and at a higher pressure after restricting fluid from exiting the first fluid path via the second fluid port. The lower pressure may be in the region of 0.5 bar to 10 bar.

[0021] Enabling fluid to exit the first fluid path via the second fluid port may comprise manipulating a valve in fluid communication with the second fluid port. The valve may be positioned downstream of the second fluid port. The valve may be incorporated in an adapter connected to the second fluid port.

[0022] Connecting the fluid source to the heat exchanger may comprise connecting a conduit to the first fluid port to bring the first fluid port into fluid communication with the fluid source.

[0023] The method may comprise connecting an adapter to the first fluid port, wherein the conduit is connected to the first fluid port via the adapter. The adapter may have a narrower outlet diameter than the diameter of the first fluid port.

[0024] The method may comprise connecting the second fluid port to a conduit. The method may comprise connecting an adapter to the second fluid port. The adapter may have a narrower outlet diameter than the diameter of the second fluid port. The adapter may comprise a valve that can be switched between an open position to enable fluid flow and a closed position to restrict fluid flow. The valve is not required to be part of the adapter and can be located in the second fluid port or at a suitable location downstream of the second fluid port.

[0025] The conduit may be connected to the second fluid port via the adapter.

[0026] The method may comprise disconnecting the first fluid port from the first fluid source after the second tube has deformed towards the third tube.

[0027] The method may comprise removing an adapter from the first fluid port after the second tube has deformed towards the third tube.

[0028] The method may comprise inserting a stopper into the first fluid port after the second tube has deformed towards the third tube.

[0029] The method may comprise removing an adapter from the second fluid port after the second tube has deformed towards the third tube.

[0030] The method may comprise inserting a stopper into the second fluid port after the second tube has deformed towards the third tube.

[0031] The method may comprise forming the heat exchanger.

[0032] The forming may comprise positioning the second tube in the first tube. The forming may comprise positioning the third tube in the second tube. The forming may comprise joining the ends of the second tube to the ends of the first tube to form the enclosed space between the first tube and the second tube that defines the first fluid path.

[0033] The method may comprise attaching the first fluid port and second fluid port to the first tube.

[0034] The method may comprise installing the heat exchanger in a building. Installing the heat exchanger may comprise connecting the first and second fluid ports to pipework in the building such that fluid flows into the first fluid path from a source of cold water and flows out of the first fluid path towards a water heater and / or a water outlet. Installing the heat exchanger may comprise connecting the second fluid path to a source of warm water. Installing the heat exchanger may comprise connecting the second fluid path to a shower drain.

[0035] The first tube may be made of a metal or metal alloy. The first tube may be made of a copper or copper alloy. The first tube may be made of stainless steel. Other materials may be used.

[0036] The second tube may be made of a metal or metal alloy. The second tube may be made of a copper or copper alloy. The second tube may be made of stainless steel. Other materials may be used.

[0037] The third tube may be made of a metal or metal alloy. The third tube may be made of a copper or copper alloy. The third tube may be made of stainless steel. Other materials may be used.

[0038] The second tube may be made of a different metal or metal alloy to the first tube and third tube.

[0039] The first tube, second tube, and third tube may be made of a copper or copper alloy, with the third tube having a different copper or copper alloy composition to the first tube and second tube. The second tube may be made from a softer copper or copper alloy material to the first tube and third tube.

[0040] The first tube may comprise at least one rib that extends at least partially along the length of the first tube. The at least one rib may extend along the full length of the first tube. The at least one rib may extend along the inner surface of the first tube facing the second tube. In an example, the at least one rib comprises three ribs.

[0041] The second tube may comprise at least one rib that extends at least partially along the length of the second tube. The at least one rib may extend along the full length of the second tube. The at least one rib may extend along the outer surface of the second tube that faces the first tube. In an example, the at least one rib comprises three ribs.

[0042] The enclosed space between the first tube and the second tube may comprise one or more turbulence promoting features. The one or more turbulence promoting features may comprise a profiled outer surface of the second tube. The one or more turbulence promoting features may comprise a profiled inner surface of the first tube. The third tube may comprise one or more turbulence promoting features. The one or more turbulence promoting feature may comprise a profiled inner surface of the third tube.

[0043] The first fluid port may comprise a plurality of fluid ports.

[0044] The second fluid port may comprise a plurality of fluid ports.

[0045] According to a second aspect of the disclosure, there is provided a system.

[0046] The system comprises a fluid source connectable to a first fluid port of a heat exchanger, wherein the first fluid port is in fluid communication with a first fluid path formed in an enclosed space between a first tube of the heat exchanger and a second tube of the heat exchanger positioned in the first tube, wherein the first fluid path is accessible only by the first fluid port and a second fluid port of the heat exchanger also in fluid communication with the first fluid path.

[0047] The system comprises a valve for controlling the flow of fluid exiting the first fluid path via the second fluid port, wherein the fluid source is configured to deliver fluid via the first fluid port, while the valve is restricting fluid for exiting the first fluid path via the second fluid port, so as to cause the second tube to deform towards a third tube positioned in the second tube, thereby decreasing the separation between the first fluid path and a second fluid path defined by the third tube.

[0048] The second tube is more easily deformable than the first tube and the third tube.

[0049] The system may further comprise the heat exchanger.

[0050] A heat exchanger comprising a first tube, a second tube positioned within the first tube, and a third tube positioned within the second tube, a first fluid path formed in an enclosed spaced between the first tube and the second tube, a second fluid path formed through the third tube, the second fluid path being connectable to a drain of a shower such that shower waste water flows along the second fluid path to a waste water outlet, the first fluid path being connectable between a cold water supply and a mixing valve and / or a water heater for the shower, so that waste heat is transferrable from the second fluid path to the first fluid path to warm the cold water flowing through the first fluid path in use, the second tube being hydroformed together with the third tube prior to installation.

[0051] Ideally, the heat exchanger has a first fluid port and second fluid port connected to the first fluid path, the first fluid port and / or the second fluid port having sealing means for sealing the ports. Preferably, the heat exchanger has a first fluid port and second fluid port connected to the first fluid path, the first fluid port and / or the second fluid port having sealing means for sealing the ports during transport and / or storage preventing contamination of the heat exchanger.

[0052] Ideally, the heat exchanger is leak proof following leak testing in the factory prior to installation.

[0053] BRIEF DESCRIPTION OF FIGURES

[0054] Figure 1 shows a sectional view of an example heat exchanger according to aspects of the present disclosure;

[0055] Figure 1a shows a cutaway portion of the heat exchanger o Figure 1 ;

[0056] Figure 2 shows a schematic diagram of an example heat exchanger according to aspects of the present disclosure;

[0057] Figure 3 shows a schematic diagram of an example system according to aspects of the present disclosure; and

[0058] Figure 4 shows a flow diagram of an example method according to aspects of the present disclosure; and

[0059] Figure 5 shows a flow diagram of another example method according to aspects of the present disclosure.

[0060] DETAILED DESCRIPTION

[0061] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0062] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

[0063] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0064] The present disclosure is directed towards a system and method for delivering fluid to a heat exchanger to improve the thermal efficiency of the heat exchanger prior to installation of the heat exchanger in an end location such as a building.

[0065] Figure 1 shows an example heat exchanger 100 in accordance with aspects of the present disclosure. Figure 2 shows the heat exchanger 100 installed within a building. The heat exchanger 100 of this example is used to recover heat from waste water.

[0066] The heat exchanger 100 comprises a first tube 102, a second tube 104 positioned within the first tube 102, and a third tube 106 positioned within the second tube 104. The first tube 102 may be referred to as the outer tube, the second tube 104 may be referred to as the middle tube, and the third tube 106 may be referred to as the inner tube.

[0067] A first fluid flow path 108 is provided in the space between the first tube 102 and the second tube 104. The space is bounded by the inner wall of the first tube 102 and the outer wall of the second tube 104. The space is an enclosed space typically formed by joining the ends 110, 112 (Figure 2) of the first tube 102 to the ends 110, 112 (Figure 2) of the second tube 104 such as by soldering. Other suitable joining methods such as welding and adhesive bonding may be used.

[0068] A second fluid flow path 114 is provided through the third tube 106. The second fluid flow path 114 is thus provided in the space bounded by the inner wall of the third tube 106.

[0069] The heat exchanger 100 comprises a first fluid port 116 (Figure 2) and a second fluid port 118 (Figure 2) that are in fluid communication with the first fluid path 108. The first fluid port 116 and second fluid port 118 are accessible from the outer surface of the first tube 102 and may be connected to or formed as part of the first tube 102. In some examples, the first fluid port 116 and second fluid port 118 are soldered to the first tube 102. Other suitable joining methods such as welding and adhesive bonding may be used.

[0070] The first fluid port 116 and second fluid port 118 are spaced apart from one another such that the first fluid port 116 is close to one end 110 and the second fluid port 118 is close to other end 112. Access to the first fluid path 108 is only provided by the first fluid port 116 and the second fluid port 118. The first fluid path 108 is otherwise sealed off by the walls of the first tube 102 and second tube 104.

[0071] As shown in Figure 1 a, the space between the first tube 102 and second tube 104 may comprise one or more turbulence promoting features 130. The one or more turbulence promoting features may comprise a profiled inner surface of the first tube 102. The profile may comprise grooves, fins, studs 130, wire, or the like. The one or more turbulence promoting features may comprise a profiled outer surface of the second tube 104. The profile may comprise grooves, fins, studs or the like.

[0072] While not shown in the figures, the third tube 106 may comprise one or more turbulence promoting features. The one or more turbulence promoting features may comprise a profiled inner surface of the third tube 106. The profile may comprise grooves, fins, wire, or the like.

[0073] While not shown in the figures, the first tube 102 may comprise one or more ribs extending at least partially along the length of the first tube 102. The second tube 104 may comprise one or more ribs extending at least partially along the length of the second tube 104. In some examples, the first tube 102 and second tube 104 each comprise three ribs. The third tube 106 generally does not comprise any ribs extending in the length direction of the third tube 106 but may comprise ribs or other structures extending circumferentially around the inner surface of the third tube 106 to promote turbulence as described above as well as to aid in leakage detection.

[0074] The second tube 104 is more easily deformable than the first tube 102 and the third tube 106. The second tube 104 may be more easily deformable by virtue of one or a combination of the material used for the second tube 104, the material thickness used for the second tube 104, or structural features 132 incorporated into the second tube 104 that enhance deformation such as a pleat 132. When the fluid between the outer tube 102 and middle tube 104 is pressurised, the folds 132 are pressed together, and the middle tube 104 is pressed against the inner tube 106. One or more additional pleats 132 can be angularly orientated around the diameter of the middle tube 104 where required.

[0075] The first tube 102, second tube 104, and third tube 106 may be made of a metal or metal alloy such as copper or a copper alloy. The second tube 104 may be made of a softer copper or copper alloy material than the first tube 102 or third tube 106.

[0076] As shown in Figure 2, the heat exchanger 100 can installed within a building as part of a heating and plumbing system 200. The second tube 104 is shown in Figure 2 being present in the heat exchanger 100.

[0077] The first fluid port 116 is connected to a cold water supply pipe 202. The second fluid port 118 is connected to a pipe 204 that flows to a water heater 206 and a mixer valve 208 of a shower 210. The water heater 206 is able to heat water for delivery to the shower 210. A drain 214 of the shower 212 is connected via a pipe 216 to an inlet 120 of the third tube 106. A waste water pipe 218 that flows to a sewer is connected to an outlet 122 of the third tube 106.

[0078] In operation, cold tap water flows from cold water supply pipe 202 into the first fluid path 108 via the first fluid port 116. The water flows towards the water heater 206 and mixer valve 208 via the second fluid port 118. The waste water from the shower 210 flows via the drain 214 into the second fluid path 114 via the inlet 120. The waste water flows towards the sewer via the outlet 122. The flow of water through the heat exchanger 100 towards the water heater 206 and mixer valve 208 is in counterflow to the flow of waste shower water through the heat exchanger 100. The cold water flowing through the first fluid path 108 is preheated by heat transfer from the hotter waste shower water flowing through the second fluid path 114. The preheated water flows to the mixer valve 208 where it can be used directly or to the water heater 206. In the water heater 206, the already preheated water is further heated and directed to the mixing valve 208 via hot water outlet pipe 218. The heat exchanger 100 is arranged essentially vertically so that the hot shower water flows downward under the influence of gravity as a film over the inner surface of the third tube 106.

[0079] In the above examples, the first fluid port 116 serves as an inlet via which fluid enters the first fluid path 108 of the heat exchanger 100 when installed in a building. It will be appreciated that the second fluid port 118 can be connected to the cold water supply pipe and thus serve as the inlet for the first fluid path 108. Any of each of the first fluid port 116 and second fluid port 118 may comprise a plurality of fluid ports.

[0080] Figure 1 shows the heat exchanger 100 prior to the application of the system and method according to aspects of the present disclosure. There is a gap G between the second tube 104 and third tube 106. Figure 3 shows an example system 300 according to aspects of the present disclosure. The system 300 is used to deform the second tube 104 of the heat exchanger 100 into closer contact with the third tube 106 thus reducing or removing the gap between the second tube 104 and third tube 106, to thereby improve the thermal transfer efficiency of the heat exchanger 100.

[0081] The system 300 is used prior to the heat exchanger 100 being installed in a building and may be used in a factory after the heat exchanger 100 is formed. Beneficially, the system can be used in the same factory location that forms the heat exchanger 100.

[0082] The system 300 comprises a fluid source 302, adapters 304, 306, a first conduit 308, and a second conduit 310. The adapter 304 is connectable to the first fluid port 116 and the adapter 306 is connectable to the second fluid port 118. The first conduit 308 is connectable to the first fluid port 116 via adapter 304. The second conduit 310 is connectable to the second fluid port 118 via adapter 306. The first conduit 304 is connected to fluid source 302.

[0083] The adapters 304, 306 facilitate connection between the conduits 308, 310 and the first fluid ports 116, 118. The adapters 304, 306 may have outlets of reduced diameter as compared to the first and second fluid ports 116, 118.

[0084] The system further comprises a valve 312 that can be manipulated to either enable or restrict fluid flow out of the first fluid path via the second fluid port 118. The valve 312 may be incorporated into the second fluid port 118 or arranged downstream of the second fluid port 118. The valve 312 may be incorporated into the adapter 306 or second conduit 306.

[0085] The fluid source 302 is operable to deliver fluid to the first fluid path 108 via the first fluid port 116. The fluid source 302 is operable to deliver fluid at high pressure. The fluid source 302 is operable to deliver fluid at different pressure levels. The fluid source 302 may be a fluid pump. The fluid delivered by the fluid source 302 is typically water. In general, the fluid may be any non-compressible fluid as appropriately selected by the skilled person. For example, the fluid may be oil.

[0086] In an example operation, the heat exchanger 100 is laid horizontally. The adapter 304 is connected to the first fluid port 116 and the adapter 306 is connected to the second fluid port 118. The first fluid conduit 308 is connected to the adapter 304 to bring the first fluid port 116 into fluid communication with the fluid source 302. The second conduit 310 is connected to the adapter 306 such that the second fluid port 118 is in fluid communication with the conduit 310 and valve 312. The second conduit 310 may be in fluid communication with a drain or may be connected back to the fluid source 302 to allow fluid to be recirculated to the fluid source 302.

[0087] The valve 312 is configured to the open position such that fluid is able to exit the first fluid path 108 via the second fluid port 118.

[0088] While the valve 312 is in the open position, the fluid source 302 is operated to deliver fluid to the first fluid path 108 via the first fluid port 116. This flushes the first fluid path 108 with fluid to displace any air within the first fluid path 108 and fill the first fluid path 108 with fluid. The fluid source is operated to deliver fluid at a low pressure such as in the region of 0.5 bar to 10 bar.

[0089] The valve 312 is then configured to the closed position such that fluid is restricted from exiting the first fluid path 108 via the second fluid port 118.

[0090] While the valve 312 is in the closed position, the fluid source 302 is operated to deliver fluid to the first fluid path 108 via the first fluid port 116. As fluid is restricted from exiting the first fluid path 108 via the second fluid port 118, the pressure within the first fluid path 108 increases. The second tube 104 is more deformable than the first tube 102 or third tube 106 and as such the second tube 104 deforms in preference to the first tube 102 and third tube 106 as a consequence of the increased pressure and / or structural feature 132. The second tube 104 deforms towards the third tube 106 to decrease the separation between the first fluid path 108 and second fluid path 114. The fluid source is operated to deliver fluid at a high pressure such as in the region of 20 bar to 50 bar. The particularly pressure or pressure range chosen will depend on, for example, the type of materials used for the second tube and the thickness of the second tube. In some examples, the pressure is in the region of 30 bar to 35 bar. The deformation of the second tube 104 towards the third tube 106 typically means that the second tube 104 conforms to the outer surface of the third tube 106. The system 300 therefore operates to hydroform the second tube 104.

[0091] After the deformation of the second tube 104, the fluid source 302 ceases to deliver fluid to the first fluid path 108. Fluid may be allowed to escape from the first fluid path 108 by opening valve 312 to reduce the pressure within the first fluid path 108. The first fluid path 108 may be drained of water and flushed with air to dry it. The first conduit 308 and second conduit 310 are disconnected from the first fluid port 116 and second fluid port 118. The adapters 304, 306 are removed. Sealing components such as stoppers (not shown) are inserted into the first fluid port 116 and second fluid port 118. The stoppers are inserted to seal off the first fluid path 108 and prevent contamination while the heat exchanger 100 is stored or transported. The stoppers are removed prior to connecting the heat exchanger into a building.

[0092] The heat exchanger 100 may then be transported from the factory to a building for installation.

[0093] The system 300 enables the efficiency of the heat exchanger 100 to be increased by reducing the separation between the second tube 104 and third tube 106 such as by making a direct connection between the second tube 104 and the third tube 106. The deformation of the second tube 104 is permanent in the sense that it remains after the pressure in the first fluid path 108 is reduced. The decrease in separation between the first fluid path 108 and second fluid path 114 is maintained when the heat exchanger 100 is subsequently installed within a building.

[0094] In this example, the same fluid source 302 is used to deliver fluid during the flushing stage and the pressuring stage when the fluid flow out of the first fluid path 108 is restricted. It will be appreciated that different fluid sources could be used for the flushing and pressuring stages. This may involve connecting the first fluid port 116 to a first fluid source to flush the first fluid path 108 and then connecting the first fluid port 116 to a second fluid source to pressurise the first fluid path 108.

[0095] Figure 4 shows an example method of improving the efficiency of the heat exchanger 100 according to aspects of the present disclosure. The method may be performed by the system of Figure 3. Step 401 comprises connecting the first fluid port 116 of the heat exchanger 100 to the fluid source 302.

[0096] Step 402 comprises restricting fluid from exiting the first fluid path 108 via the second fluid port 118.

[0097] Step 403 comprises operating the fluid source 302 to deliver fluid to the first fluid path 108 via the first fluid port 116, while fluid is restricted from exiting the first fluid path 108 via the second fluid port 118, so as to cause the second tube 104 to deform towards the third tube 106, thereby decreasing the separation between the first fluid path 108 and the second fluid path 114.

[0098] The present method does not rely on the mains water supply to cause a deformation of the second tube 104 towards the third tube 106 and instead uses a process performed prior to the installation of the heat exchanger 100 and which causes a permanent deformation of the second tube 104 into close conformity with the third tube 106. This provides a greater reduction in separation between the first fluid path 108 and the second fluid path 114 and is not affected by variations in the pressure of the cold water supply in use. Moreover, the method enables any leaks in the heat exchanger 100 to be easily identified (e.g., at the factory) prior to installation of the heat exchanger 100 in the building.

[0099] Figure 5 shows another example method according to aspects of the present disclosure.

[0100] Step 501 comprises forming the heat exchanger 100. This may comprise positioning the second tube 104 in the first tube 102. The ends 108, 110 of the second tube 104 are then joined to the ends 108, 110 of the first tube 102 such as by soldering to form the enclosed space between the first tube 102 and second tube 104 that defines the first fluid path 108. The first fluid port 116 and second fluid port 118 are then joined to the first tube 102 such as by soldering. The third tube 106 is then positioned in the second tube 104.

[0101] Step 502 comprises connecting the first fluid port 116 of the heat exchanger 100 to the fluid source 302.

[0102] Step 503 comprises enabling fluid to exit the first fluid path 108 via the second fluid port 118. Step 504 comprises operating the fluid source 302 to deliver fluid via the first fluid port 116 while fluid is enabled to exit the first fluid path 108 via the second fluid port 118.

[0103] Step 505 comprises restricting fluid from exiting the first fluid path 108 via the second fluid port 118.

[0104] Step 506 comprises operating the fluid source 302 to deliver fluid via the first fluid port 116, while fluid is restricted from exiting the first fluid path 108 via the second fluid port 118, so as to cause the second tube 104 to deform towards the third tube 106, thereby decreasing the separation between the first fluid path 108 and the second fluid path 114.

[0105] This method may be performed in a single location such as a factory.

[0106] Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

[0107] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0108] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0109] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A method comprising: connecting a first fluid port of a heat exchanger to a fluid source, the first fluid port is in fluid communication with a first fluid path formed in an enclosed space between a first tube of the heat exchanger and a second tube of the heat exchanger positioned in the first tube, wherein the first fluid path is accessible only by the first fluid port and a second fluid port of the heat exchanger also in fluid communication with the first fluid path; restricting fluid from exiting the first fluid path via the second fluid port; operating the fluid source to deliver fluid via the first fluid port, while fluid is restricted from exiting the first fluid path via the second fluid port, so as to cause the second tube to deform towards a third tube positioned in the second tube, thereby decreasing the separation between the first fluid path and a second fluid path defined by the third tube, wherein the second tube is more easily deformable than the first tube and the third tube.

2. A method as claimed in claim 1 , wherein prior to restricting fluid from exiting the first fluid path via the second fluid port, the method comprises: enabling fluid to exit the first fluid path via the second fluid port; and operating the fluid source to deliver fluid via the first fluid port while fluid is enabled to exit the first fluid path via the second fluid port.

3. A method as claimed in claim 2, wherein the fluid is delivered at a lower pressure prior to restricting fluid from exiting the first fluid path via the second fluid port and at a higher pressure after restricting fluid from exiting the first fluid path via the second fluid port.

4. A method as claimed in any preceding claim, wherein restricting fluid from exiting the first fluid path via the second fluid port comprises manipulating a valve in fluid communication with the second fluid port.

5. A method as claimed in any preceding claim, wherein connecting the fluid source to the heat exchanger comprises connecting a conduit to the first fluid port to bring the first fluid port into fluid communication with the fluid source.

6. A method as claimed in claim 5, further comprising connecting an adapter to the first fluid port, wherein the conduit is connected to the first fluid port via the adapter.

7. A method as claimed in any preceding claim, comprising connecting the second fluid port to a conduit.

8. A method as claimed in claim 7, comprising connecting an adapter to the second fluid port, wherein the conduit is connected to the second fluid port via the adapter.

9. A method as claimed in any preceding claim, comprising disconnecting the first fluid port from the fluid source after the second tube has deformed towards the third tube.

10. A method as claimed in claim 9, comprising inserting a stopper into the first fluid port.

11. A method as claimed in claim 9 or 10, comprising inserting a stopper into the second fluid port.

12. A method as claimed in any preceding claim, wherein the fluid source is operated to deliver fluid at a pressure of at least 20 bar.

13. A method as claimed in claim 12, wherein the fluid source is operated to deliver fluid at a pressure of at least 25 bar.1914. A method as claimed in claim 13, wherein the fluid source is operated to deliver fluid at a pressure of at least 30 bar.

15. A method as claimed in any of claims 12 to 14, wherein the fluid source is operated to deliver fluid at a pressure of less than 50 bar.

16. A method as claimed in claim 15, wherein the fluid source is operated to deliver fluid at a pressure of less than 35 bar.

17. A method as claimed in any preceding claim, further comprising forming the heat exchanger.

18. A method as claimed in claim 17, wherein forming the heat exchanger comprises: positioning the second tube in the first tube; and positioning the third tube in the second tube.

19. A method as claimed in claim 18, wherein the forming further comprises joining the ends of the second tube to the ends of the first tube to form the enclosed space between the first tube and second tube that defines the first fluid path.

20. A method as claimed in claim 18 or 19, further comprising attaching the first fluid port and the second fluid port to the first tube.

21. A method as claimed in any preceding claim, further comprising installing the heat exchanger in a building.

22. A method as claimed in claim 21 , wherein installing the heat exchanger comprises connecting the first and second fluid ports to pipework in the building such that fluid flows into the first fluid path from a source of cold water and flows out of the first fluid path towards a water heater and / or a water outlet.

23. A method as claimed in claim 22, wherein installing the heat exchanger comprises connecting the second fluid path to a source of warm water.2024. A method as claimed in claim 23 wherein the second fluid path is connected to a shower drain.

25. A system comprising: a fluid source connectable to a first fluid port of a heat exchanger, wherein the first fluid port is in fluid communication with a first fluid path formed in an enclosed space between a first tube of the heat exchanger and a second tube of the heat exchanger positioned in the first tube, wherein the first fluid path is accessible only by the first fluid port and a second fluid port of the heat exchanger also in fluid communication with the first fluid path; and a valve for controlling the flow of fluid exiting the first fluid path via the second fluid port, wherein the fluid source is configured to deliver fluid via the first fluid port, while the valve is restricting fluid for exiting the first fluid path via the second fluid port, so as to cause the second tube to deform towards a third tube positioned in the second tube, thereby decreasing the separation between the first fluid path and a second fluid path defined by the third tube, wherein the second tube is more easily deformable than the first tube and the third tube.

26. A heat exchanger comprising a first tube, a second tube positioned within the first tube, and a third tube positioned within the second tube, a first fluid path formed in an enclosed spaced between the first tube and the second tube, a second fluid path formed through the third tube, the second fluid path being connectable to a drain of a shower such that shower waste water flows along the second fluid path to a waste water outlet, the first fluid path being connectable between a cold water supply and a mixing valve and / or a water heater for the shower, so that waste heat is transferrable from the second fluid path to the first fluid path to warm the cold water flowing through the first fluid path in use, the second tube being hydroformed together with the third tube prior to installation.

27. A heat exchanger as claimed in claim 26, wherein the heat exchanger has a first fluid port and second fluid port connected to the first fluid path, the first fluid port and / or the second fluid port having sealing means for sealing the ports.

28. A heat exchanger as claimed in claim 27, wherein the heat exchanger has the first fluid port and the second fluid port connected to the first fluid path, the first fluid port and / or the second fluid port having sealing means for sealing the ports during transport and / or storage to avoid contamination of the heat exchanger.

29. A heat exchanger as claimed in any one of the claims 26 to 28, wherein the heat exchanger is leak proof tested in a range of pressures from 10 to 50 bar prior to installation.

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