AU2018204484B2 - Water circulation system - Google Patents

Abstract

A fluid circulation system 10 includes at least one primary line 14. The at least one primary line 14 has a first mains end 30 connected to a main supply pipe 24 and a second utilisation end 32 where the fluid is utilisable. The system 10 includes an auxiliary line 50 connected at a first end 52 to the at least one primary line 14 and connected at a second end 56 to the at least one primary line 14. The system 10 includes a heater 72 which heats the fluid in the auxiliary line 50. A flow control mechanism 78 is provided on the auxiliary line 50. The flow control mechanism 78 stops a flow of the fluid in the auxiliary line 50 when the flow of fluid in the auxiliary line 50 or at least one primary line increases above a predetermined level. 1/2 C~CN co c Go 0 m CD cn0a E E0 ~0 4... ~Io c. CL% (4 4

Description

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"Water circulation system"

Technical Field

[0001] The present disclosure relates to a water circulation system for maintaining the temperature of a fluid in at least one primary line.

Background

[0002] In buildings, plumbing systems are used to transport hot and cold water from one place to another. With hot water systems, the water is typically heated in one place and delivered by pipes to another place where it is used. As the hot water travels along hot water supply pipes, it may lose some heat to its surroundings and begin to cool. When hot water is not being drawn from a hot water supply pipe, the water in the pipe may become stationary and lose more heat to its surroundings. As a result, when water is next drawn from the hot water pipe through a tap or fixture, the water is cold and it may take some time for hot water to travel from the hot water source through the pipe to the tap or fixture. This may result in wasted water and may also inconvenience users while they wait for hot water to be delivered through the pipe.

[0003] In some buildings (for example, multistorey office or apartment buildings), to reduce the lag time in the delivery of hot water through a hot water pipe, hot water may be circulated vertically through the building in risers. On each floor of the building, branch pipes may be run horizontally from the riser to circulate hot water on each floor. Hot water which is not drawn off through the branch pipes is circulated back to the risers and through them back to a heater where it is reheated.

[0004] In this way, it may be possible to circulate hot water close to individual apartments (offices, tenancies, etc.) and thereby reduce the time taken for hot water to be delivered to a tap or fixture within the apartment. A hot water meter within the apartment can accurately measure hot water consumption and that consumption can be billed appropriately.

[0005] However, in some cases, water authorities require water meters to be installed centrally for example in a common central riser cupboard, which may be located some distance from the apartment. In that case, circulating water in the manner described above is problematic as any water that passes through the water meter will be counted as consumption and billed accordingly.

[0006] If the water meter is installed in a common central riser cupboard, there may be a long length of pipe (a dead leg) between the riser cupboard and the apartment resulting in a long lag time for hot water delivery and also water wastage.

[0007] In such situations, heat tracing can be used to heat the length of pipe between the riser cupboard and the apartment. A heat trace is an electrical heating element which is run along the pipe and which is used to heat the pipe and the water within the pipe. Heat tracing in this way requires both electrical wiring and electricity consumption and it increases cost and adds to the complexity of the plumbing. When the water in the pipe is cold, heat tracing may take some time to heat the water in the pipe. In addition, heat tracing typically requires the use of metal piping, for example, copper piping.

[0008] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0009] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary

[0010] Disclosed herein is a system which maintains a temperature of a fluid in a plurality of primary lines (or pipes), each primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to each primary line by a plurality of branch supply pipes and connected at a second end to each primary line by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary line; a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when a flow of fluid in the branch supply pipe or its associated primary line increases above a predetermined threshold.

[0011] Also disclosed herein is a system, comprising: a plurality of primary lines, each primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable; an auxiliary line connected at a first end to each primary line by a plurality of branch supply pipes and connected at a second end to each primary line by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary line; and a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when the flow of fluid in the branch supply pipe or its associated primary line increases above a predetermined level.

[0012] Each flow control mechanism may stop the flow of the fluid in its associated branch supply line in response to an increase in the flow rate of the fluid in the branch supply pipe or its associated primary line above a predetermined flow rate.

[0013] Each flow control mechanism may stop the flow of the fluid in its associated branch supply pipe in response to an increase in a pressure differential between a pressure of the fluid upstream of the flow control mechanism and a pressure of the fluid downstream of the flow control mechanism above a predetermined pressure differential.

[0014] The heater maybe a heat exchanger. A heat source of the heat exchanger maybe fluid drawn from the main supply pipe.

[0015] The branch supply pipes maybe connected to the primary lines at a first position toward the first mains end. The branch return pipes may be connected to the primary lines at a second position at the utilisation end or in the vicinity of the second end.

[0016] The system may further comprise a pump connected to the auxiliary line for circulating fluid drawn from the primary lines via the branch return pipes through the auxiliary line and back to the primary lines via the plurality of branch supply pipes.

[0017] The system may comprise a housing within which each of the pump, the heat exchanger and the stop valves are housed.

[0018] A meter which measures an amount of fluid which flows from the main supply pipe into the primary line may be provided in each primary line.

[0019] The system may further comprise an isolation valve for each branch supply pipe which is operable to stop the flow of the fluid within its respective branch supply pipe independently of the flow control mechanism.

[0020] The isolation valve may be manually operable to stop the flow of the fluid within its respective branch supply pipe.

[0021] The system may further comprise amain shut off mechanism which is operable to stop the flow of the fluid through the system from the branch return pipes through the auxiliary line to the branch supply pipes.

[0022] The main shut off mechanism may be provided on the auxiliary line.

[0023] The system may further comprise a timer which controls the main shut off mechanism.

[0024] The system may further comprise a non-return valve in each branch supply pipe to prevent a flow of the fluid from the primary line associated with each branch supply pipe along the branch supply pipe.

[0025] The fluid may be water.

[0026] Also disclosed herein is an assembly for maintaining the temperature of a fluid in a plurality of primary lines, the primary lines being connected to a main supply pipe, the assembly comprising: a housing which houses components of the assembly; an inlet pipe which passes through the housing and through which fluid from the primary lines flows into the assembly; a heater provided within the housing and which heats the fluid from the inlet pipe; a plurality of outlet pipes which pass through the housing and through which fluid from the heater flows out of the assembly to the primary lines; and a flow control mechanism provided for each outlet pipe which stops the flow of fluid in the outlet pipe when the flow of the fluid in the outlet pipe or its associated primary line increases above a predetermined level.

[0027] Also disclosed herein is a system which maintains a temperature of a fluid in at least one primary line, the at least one primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to the at least one primary line and connected at a second end to the at least one primary line; a heater which heats the fluid in the auxiliary line; a flow control mechanism to stop a flow of the fluid in the auxiliary line when a flow of fluid from the auxiliary line into primary line or in the primary line increases above a predetermined threshold.

Brief Description of Drawings

[0028] Figure 1 is a schematic diagram of a system for maintaining the temperature of a fluid in at least one primary pipe or line according to an embodiment disclosed herein.

[0029] Figure 2 is a schematic diagram of an assembly for maintaining the temperature of a fluid being at least one primary pipe or line according to an embodiment disclosed herein.

Description of Embodiments

[0030] In the figures, reference numeral 10 generally designates an exemplary embodiment of a system for maintaining the temperature of a fluid 12 in at least one primary line 14. In the embodiment shown in Figure 1, the system 10 is shown installed on one floor of a multi-floor building 18 (not shown in the figures). The building 18 has a central hot water plant (not shown in the figures) provided, in this embodiment, at a position above the floor. Hot water is circulated from the central hot water plant throughout the building 18 via central riser pipes 22 which include a hot water supply riser 24 (the main supply pipe) which carries hot water from the central hot water plant and a hot water return riser 26 which returns unused water to the hot water plant.

[0031] As shown in Figure 1, there are four primary lines 14 (14a - 14d). Each primary line 14 is a hot water supply pipe for supplying hot water (the fluid 12 in this embodiment) from the hot water supply riser 24 to an apartment 28 (28a - 28d) where the hot water 12 can be used. For simplicity, only two apartments 28a and 28b are shown in detail. Apartments 28c and 28d are identical to apartments 28a and 28b. Each hot water supply pipe 14 has a first mains end 30 connected to the hot water supply riser 24 and a second utilisation end 32 in the apartment 28 where the hot water 12 can be used at one or more fixtures 34. The fixtures 34 may be, for example, a laundry fitting 36, kitchen tap 38, a shower 40, and a bathroom tap 42. The fixtures 34 are not limited to these examples. In this embodiment, the fixtures 34 are connected to the hot water supply pipe 14 by fixture branch pipes 44. As can be seen in Figure 1, in the embodiment shown in Figure 1, the fixtures 34 are connected to the hot water supply pipe 14 in the vicinity of the second end. The word "utilisation" in the expression "second utilisation end" has been used here to help distinguish the second end of the hot water supply pipe 14 from the first end of the hot water supply pipe 14 which is connected to the hot water supply riser 24 and it is not intended to restrict the meaning of the second end.

[0032] Cold water is also supplied to the apartment through a cold water supply pipe 46.

[0033] A hot water meter 48 (48a - 48d) is provided on each hot water supply pipe 14 for measuring the amount of water which flows from the hot water supply riser 24 into the hot water supply pipe 14.

[0034] Water pressure in the hot water supply pipes 14 results from the water pressure in the central riser pipes 22. This water pressure may be from the mains pressure supply from the water utility's network. It may also be produced as a result of gravity or it may be produced by pumps (not shown) and valves (not shown) within the central hot water plant or elsewhere in the hot water supply system, or by a combination of these . When a fixture 34 is opened (or turned on) to draw water from the hot water supply pipe 14, water in the hot water supply pipe 14 flows out of the hot water supply pipe 14 under that pressure.

[0035] As shown in Figure 1, the system 10 includes an auxiliary line 50 which is connected at a first end 52 to each of the hot water supply pipes 14 by a plurality of branch supply pipes 54. In addition, the auxiliary line 50 is connected at a second end 56 to each of the hot water supply pipes 14 by a plurality of branch return pipes 58. As explained above, in this embodiment, there are four hot water supply pipes 14 (one for each apartment 28). There are also four branch supply pipes 54 (54a - 54d), one for each hot water supply pipe 14. There are also four branch return pipes 58 (58a - 58d), one for each hot water supply pipe 14.

[0036] In the embodiment shown in Figure 1, the branch supply pipes 54 are connected to the hot water supply pipes 14 at a first position 60 toward the first mains end 30 where the hot water supply pipes 14 are connected to the hot water supply riser 24. In addition, the branch return pipes 58 are connected to the hot water supply pipes 14 at a second position 62 which is in the vicinity of the utilisation end 32. In other words, the point (the first position 60) at which the branch supply pipes 54 are connected to the hot water supply pipes 14 is closer to the hot water supply riser 24 than the point (the second position 62) at which the branch return pipes 58 are connected to the hot water supply pipes 14. It will be appreciated that the actual location of the second position may vary and may be for example after the point at which the last fixture 34 is connected to the hot water supply pipe 14. In addition, additional fixtures 34 may be connected to the hot water supply pipe 14 after the second position 62 at which the branch return pipes are connected to the hot water supply pipes 14. However, as explained above, in this embodiment, the first position 60 is closer to the hot water supply riser 24 relative to the second position 62.

[0037] In this embodiment, all the fixtures 34 are within the apartment 28. It will be appreciated that, while not envisaged for the application illustrated in Figure 1, fixtures 34 could also be attached to the hot water supply pipe 14 outside the apartment, for example, at a position between the first position 60 and the apartment 28.

[0038] The auxiliary line 50 includes a common return pipe 64. As explained above, the branch return pipes 58 are connected at one end to the hot water supply pipes 14. As shown in Figure 1, at their other ends, the branch return pipes 58 are connected directly or indirectly to the common return pipe 64. As a result, water which flows through each of the branch return lines 58 from each of the hot water supply pipes 14 will be mixed or pooled in the common return pipe 64.

[0039] As shown in Figure 1, each water meter 48 is provided at a position on the hot water supply pipe 14 between the hot water supply riser 24 and the first position 60 at which the branch supply pipes 54 are connected to the hot water supply pipes 14. This arrangement prevents the water meters 48 measuring water which flows from the branch supply pipes 54 into the hot water supply pipes 14.

[0040] As can be seen in Figure 1, there are check valves 66 provided on the branch return lines 58 to prevent water from flowing back toward the fixtures 34 along the branch return lines 58. Check valves 67 are also provided between the hot water meters 48 and the first position 60 to prevent water flowing along the hot water supply pipe 14 toward the hot water meters 48. Balancing valves 68 are also provided in the branch return lines 58 in order to regulate flow within the system and to assist in maintaining a suitable flow rate as water circulates through the system.

[0041] The system 10 includes a heater 72 to heat the water in the auxiliary line 50. In the embodiment shown in the figures, the heater 72 is a heat exchanger in the form of a plate-type heat exchanger. The heat exchanger 72 is connected to the hot water supply riser 24 and the hot water return riser 26 by a heat source pipe 74. Hot water flows from the hot water supply riser 24 through the heat source pipe 74 to the heat exchanger 72 and from the heat exchanger 72 to the hot water return riser 26. Within the heat exchanger 72, there is a counter flow of water in the heat source pipe 74 and the water in the auxiliary line 50 such that heat can be transferred from the hot water in the heat source pipe 74 to the water in the auxiliary line 50.

[0042] The system 10 includes a plurality of flow control mechanisms 78 in the form of stop valves (78a - 78d) (see Figures 1 and 2). There is one stop valve 78 provided in each branch supply pipe 54. As described in more detail below, each stop valve 78 is configured to stop the flow of water in its respective branch supply pipe 54 when the flow of water in the branch supply pipe 54 or its associated hot water supply pipe 14 (that is, the hot water supply pipe 14 connected to the branch supply pipe 54) increases above a predetermined threshold.

[0043] The system 10 includes a pump 80 which is connected to the common return pipe 64 to circulate water through the auxiliary line 50 such that water flows from the hot water supply pipes 14 through the branch return pipes 58 into the common return pipe 64, then through the heat exchanger 72, and the branch supply pipes 54 toward the hot water supply pipes 14.

[0044] As can be seen from Figure 1, the system 10 includes a housing 82 within which the pump 80, the heat exchanger 72 and the stop valves 78 are housed.

[0045] Figure 2 shows another more detailed example of a housing 82 and the components within the housing 82. In the following, the same reference numbers are used for components already described above. In Figure 2, reference number 84 generally designates an assembly for maintaining the temperature of a fluid (water) in at least one primary line being a hot water pipe 14. The assembly 84 includes the housing 82. The common return pipe 64 of the auxiliary line 50 enters the housing 82 at the lower right of the figure. In addition, there are six branch supply pipes 54 (54a - 54f) which exit the housing 82 and are connected to the hot water pipes 14 (not shown in Figure 2). From the perspective of the assembly 84, the common return pipe 64 is an inlet pipe through which water drawn from the hot water pipes 14 flows into the assembly 84 and the branch supply pipes 54 are outlet pipes through which water flows out of the assembly 84. As described above, each branch supply pipe 54 can be connected to a hot water supply pipe 14. Therefore, the arrangement shown in Figure 2 is suitable for use with six hot water supply pipes 14.

[0046] As shown in Figure 2, a main shut off mechanism in the form of a main shut off valve 86 is provided in the auxiliary line 50. The main shut off valve 86 is operable to stop the flow of water in auxiliary line 50 and thereby to stop the flow of water through the assembly 84. In this way, the main shut off valve 86 is able to isolate the assembly 84. The assembly 84 includes a timer 88 which is able to control the operation of the shut off valve 86 and to isolate the assembly 84 at predetermined times (for example, during peak hot water demand periods). The timer 88 may also activate the main shut off valve 86 for short or momentary periods at regular time intervals during normal operations as a way to adjust or reset the pressure differential between the components of the assembly 84 and components outside the assembly 84 and to which the assembly 84 is connected. The main shut off valve 86 may also be operated manually in order to isolate the assembly 84 for maintenance, repairs or other reasons.

[0047] As described above, a pump 80 is connected to the auxiliary line 50 to circulate water through the auxiliary line 50.

[0048] The assembly 84 includes the heater 72 in the form of the heat exchanger. The heat exchanger 72 has an inlet 90 and an outlet 92. The assembly 84 includes a manifold 94 to which each of the branch supply pipes 54 is connected. The heat exchanger 72 is connected to the manifold 94 via a mixing valve 96. The mixing valve 96 has a first inlet 98 and a second inlet 100 and an outlet 102. The first inlet 98 is connected via a bypass pipe 104 to the common return pipe 64 on the inlet 90 side of the heat exchanger 72. The second inlet 100 is connected to the outlet 92 of the heat exchanger 72. The outlet 102 of the mixing valve 96 is connected to the manifold 94. The mixing valve 96 allows for tempering of the heated water flowing from the heat exchanger 72, if necessary. As can be seen in Figure 2, an expansion vessel 106 is connected to the manifold 94. . The expansion vessel 106 is provided to accommodate any thermal expansion of water which results due to heating of the water in the heat exchanger 72.

[0049] As explained above, each branch supply pipe 54 includes a flow control mechanism 78 in the form of a stop valve. In this embodiment, the stop valve 78 is configured to stop the flow of water in its branch supply pipe 54 in response to a pressure differential between the water pressure on the manifold 94 side of the stop valve 78 and the water pressure on the hot water supply pipe 14 side of the stop valve 78. With respect to the normal direction of flow of water through the assembly 84, that is the pressure differential between the water pressure upstream (the manifold 94 side) of the stop valve 78 and water pressure downstream (the hot water supply pipe 14 side) of the stop valve 78. When the water pressure downstream of the stop valve 78 drops below a predetermined threshold, the stop valve 78 shuts off water flow in the branch supply pipe 54. A change in the water pressure differential across the stop valve 78, in this way, such that the water pressure downstream of the stop valve falls relative to the water pressure upstream of the stop valve 78 is indicative of an increase in water flow downstream of the stop valve 78, for example, in the hot water supply pipe 14. In addition, the operation of the pump 80 which is located upstream (according to the direction of flow described above) of the stop valve 78 acts to increase the water pressure in the leg of the auxiliary line between the pump 80 and the stop valve 78.

[0050] The stop valve 78 may be for example a spring operated stop valve in which a spring biases the valve open when the pressure differential across the valve is low. When the pressure downstream of the stop valve 78 falls relative to the water pressure upstream of the stop valve 78, the biasing force of the spring is not sufficient to keep the valve open and the valve closes. In terms of flow rate, the spring may bias the stop valve 78 open against the flow of water through the stop valve 78. However, when the flow of water through the stop valve 78 increases, the biasing force of the spring is insufficient to keep the stop valve 78 open and the stop valve 78 closes.

[0051] A non-return valve 108 is also provided in each branch supply pipe 54 at a position between the stop valve 78 and the hot water supply pipe 14. The non-return valve 108 allows flow of water in a direction from the stop valve 78 toward the hot water supply pipe 14, but blocks flow of water in the reverse direction from the hot water supply pipe 14 toward the stop valve 78.

[0052] In addition, as shown in Figure 2, a branch line shut off valve 110 is provided in each branch supply pipe 54. The branch line shut off valve 110 is operable to stop the flow of water in an individual branch supply pipe 54 and thereby to isolate that branch supply pipe 54. While the branch line shut off valve 110 stops flow of water in the branch supply pipe 54, it will not prevent the flow of water in the other branch supply pipes 54. The timer 88 may also control each branch line shut off valve 110 in unison with the main shut off valve 86 or independently of the main shut off valve 86. Each branch line shut off valve 110 may have its own timer (not shown). In addition, the branch line shut off valve 110 may be operated manually to isolate its associated branch supply pipe 54 for maintenance, repairs or other reasons. In addition, the position of the non-return valve 108 and the branch line shut off valve 110 are not limited to those shown in the figures. For example, the position of the branch line shut off valve 110 and the non-return valve 108 may be reversed. In addition, the non-return valve 108 may also be positioned on the branch supply pipe 54 closer to the hot water supply pipes 14 and outside the housing 82.

Operation

[0053] In the following, the operation of the system 10 and the assembly 84 described above will be described.

[0054] As described above, each branch supply pipe 54 has a stop valve 78 which is configured to stop the flow of water in the branch supply pipe 54 when the flow of water in the branch supply pipe 54 or its associated hot water supply pipe 14 increases above a predetermined level. The predetermined level is selected, for example, such that when water is drawn from a hot water supply pipe 14 from a fixture 34 in the apartment 28, the stop valve 78 will be activated and will prevent the flow of water in the branch supply pipe 54 associated with that hot water supply 14 and apartment 28. For example, with respect to hot water supply pipe 14a and components associated with hot water supply pipe 14a, the predetermined level is selected such that when water is drawn from hot water supply pipe 14a from a fixture 34 in apartment 28a, the stop valve 78a will be actived and will prevent the flow of water in the branch supply pipe 54a. As a result, water will not flow from the branch supply pipe 54a into the hot water supply pipe 14a. Water from the hot water supply riser 24 will flow into the hot water supply pipe 14a through the hot water meter 48a to the fixture 34 of the apartment 28a. Consequently, the flow of water through the hot water meter 48a corresponds to the flow of water from the fixture 34 of the apartment 28a.

[0055] However, when all the fixtures 34 are closed (or turned off) and water is not drawn from the fixtures 34, the flow of water in the hot water supply pipe 14 will be below the predetermined level and the stop valve 78 will open to allow water to flow in the branch supply pipe 54.

[0056] The actual flow rate or pressure differential which triggers the stop valves 78 to close will depend on a number of factors, such as the size and diameter of the hot water supply pipes 14 and the level of water consumption (for example, domestic, commercial or industrial) the hot water supply pipes are intended to supply. However, for an apartment building, the system may be configured to allow a flow rate of water through the branch supply pipes 54 and the stop valves 78 of 0.021 litres/second or lower. The pump 80 can be set to circulate water at or below this rate. The flow rate of water through the common return line 64 would vary depending on the number of hot water supply pipes 14 supplying water to the common return pipe 64. For example, for the case shown in Figure 2 with six hot water supply pipes 14 and six branch supply pipes 54, when water is being circulated through the six hot water supply pipes 14 and the auxiliary line 50, the flow rate of water in the common return line 64 would be in the order of 0.126 1/sec, when the flow rate of water through each stop valve 78 is 0.021 1/sec. In this example, the flow rate at which the stop valve 78 is triggered to stop the flow of water may be 0.031/sec.

[0057] In contrast, in domestic applications, the flow rate of water from a fixture 34 such as a kitchen tap or a basin tap is typically in the order of 0.1 /sec and the flow rate of water from a shower is typically 0.15 1/sec.

[0058] With regard to temperatures, in domestic applications, such as in apartment buildings, the temperature of water in the central risers 22 will depend on the central hot water plant but, for example, may be in the range of about 60 to 65 °C. In that case, for example, the water flowing into the heat exchanger 72 would also be in the range of about 60 to 65 °C. Depending on the efficiency of the heat exchanger 72, heated water flowing in the auxiliary line 50 from the heat exchanger 72 to the manifold may be approximately 2 °C lower. In this example, water of this temperature circulating through the hot water pipes 14 and the auxiliary line 50 at the flow rates indicated above (0.021 1/sec through the stop valve 78) will be sufficient to maintain the temperature of the water within the hot water supply pipes 14 at a suitable temperature. If a mixing valve 96 is included in the system 10 as shown in Figure 2, the mixing valve 96 may be set to temper the water flowing out of the heat exchanger 72 to a temperature of about 50 °C, for example.

[0059] As described above, there is a pump 80 provided in the auxiliary line 50 to move water in the auxiliary line 50. The pump 80 moves the water such that the direction of flow of water in the auxiliary line 50 is from the branch return pipes 58 through the common return pipe 64 and the heat exchanger 72 to the manifold 94 and into the branch supply pipes 54 and finally into the hot water supply pipe 14. Therefore, the branch supply pipes 54 supply water into the hot water supply pipes 14.

[0060] In this way, the water from the individual hot water supply pipes 14 which has been pooled in the common return pipe 64 passes through the pump 80 to the heat exchanger 72. As explained above, the heat exchanger 72 is connected to the hot water supply riser 24 and the hot water return riser 26 by the heat source pipe 74. The water which is flowing through the heat source pipe 74 comes directly from the hot water supply riser 22 and is therefore close to the temperature (if not at the same temperature) as the water in the hot water supply riser 22. As the water in the auxiliary line 50 flows through the heat exchanger 72, it will be heated by the hot water in the heat source pipe 74. This heated water will then flow from the heat exchanger 72 into the manifold 94 from which it is distributed into the branch supply pipes 54 with open stop valves 78. If a stop valve 78 in a branch supply pipe 54 is closed, water will not flow from the manifold into that branch supply pipe 54. In this way, heated water from the heat exchanger 72 will flow through the branch supply pipes 54, through the open stop valves 78 and into the hot water supply pipes 14. It will flow along the hot water supply pipe 14 until it reaches the second position 62 where the branch return pipe 58 is connected to the hot water supply pipe 14. The water will be drawn into the branch return pipe 58 due to the action of the pump 80 and will flow back toward the common return pipe 64 and the heat exchanger 72 where it will be heated.

[0061] This circulation of water through the hot water supply pipes 14 (the primary lines) and the auxiliary line 50 and through the heat exchanger 72 at times when water is not being drawn from a fixture 34 in an apartment 28 (and, therefore, when the stop valve 78 is open) maintains the temperature of the water in the hot water supply pipes 14. As a result, when water is drawn from a fixture 34, the lag time between when the fixture 34 is turned on to the time when heated water flows from the fixture 34 is reduced.

[0062] In addition, as described above, when water is drawn from a hot water supply pipe 14 through a fixture 34, the shut off valve 78 on the branch supply pipe 54 which is connected to that hot water supply pipe 14 closes. This prevents pooled heated water from the heat exchanger 72 being drawn through the manifold 94 into the branch supply pipe 54 which feeds that hot water supply pipe 14. Therefore, it is possible to prevent water being drawn through the system 10 (via the branch return pipes 58, the common return pipe 64, the heat exchanger 72, the manifold 94, and branch supply pipes 54) from other hot water supply pipes 14 (and through their associated hot water meters 48) into a hot water supply pipe 14 which is supplying water to an open fixture 34.

[0063] When water is drawn from a fixture 34, the water pressure in the hot water supply pipe 14 falls. In addition, the flow of water in the hot water supply pipe 14 increases. The stop valve 78 operates in response to this pressure change or flow rate change to prevent water from flowing from the branch supply pipe 54 into its associated the hot water supply pipe 14. Therefore, when water is drawn from the fixture 34, water will flow from the hot water supply riser 24 through the hot water supply pipe to the apartment 28 and pooled water will not flow from the manifold 94 into the branch supply pipe 54 and into the hot water supply pipe 14.

[0064] In the embodiments described above, the first end 52 of the auxiliary line 50 is connected to the hot water supply pipe 14 at the first position 60 and the second end 56 is connected to the hot water supply pipe 14 at the second position 62. As a result, the auxiliary line 50 is configured such that water flows from the hot water pipe 14 into the auxiliary line 50 from the second position 62 which is closer to second utilization end 32 relative to the first position 60 and flows through the auxiliary line 50 into the hot water pipes 14 at the first position which is closer to the hot water supply riser 24 relative to the second position 62. Thus circulation of water through the primary line 14 into the auxiliary line 50 and back into the primary line 14 as shown in Figure 1 is generally clockwise.

[0065] However, other configurations are possible. For example, the first end of the auxiliary line may be connected to the hot water supply pipe at the second position closer to the utilization end and the second end of the auxiliary line may be connected to the hot water supply pipe at the first position closer to the hot water supply riser 24. In such a configuration, the auxiliary line would be configured such water flows into the auxiliary line from the hot water supply pipe at the first position 60 and flows from the auxiliary line into the hot water supply pipes at the second position.

[0066] In the embodiment described above, the stop valve 78 was responsive to the pressure differential across the stop valve 78 such that a drop in water pressure downstream of the stop valve 78 resulted in the stop valve 78 stopping the flow of water in its associated branch supply pipe 54.

[0067] However, other types of stop valve are possible. Activated isolation valves triggered by electrically or mechanically controlled flow or pressure switches would also be suitable. Electrically activated valves which are responsive to signals from a sensor which detects changes in the flow of water or water pressure in the branch supply pipe or in the hot water supply pipe are also possible. In such cases, the location of the sensor is not particularly limited. For example, the sensor could be positioned in the hot water supply pipe 14 between the hot water meter 48 and the point at which the branch supply pipe is connected to the hot water supply pipe 14. The sensor could also be positioned at other positions along the hot water supply pipe 14 or on the branch fixture pipe 44.

[0068] In the embodiment shown in Figure 2, a mixing valve 96 is provided to allow for tempering of the heated water flowing from the heat exchanger 72 if necessary. In other embodiments, see for example Figure 1, the mixing valve 72 is omitted.

[0069] In the embodiments described above, the fluid is water 12 and the primary line 14 supplies hot water to apartments. However, other configurations and applications are possible. For example, in colder climates or environments, the system could be used to maintain the temperature of water in cold water pipes to prevent the water in them from becoming too cold or freezing.

[0070] In the embodiment described above, components of the system 10 are provided in a housing 82. This has the convenience that the components of the system 10 can be accessed easily for maintenance and repair. The system is not limited to this arrangement other configurations are possible. For example, the components may be housed in more than one housing or they may be position along the auxiliary line 50 without a housing.

[0071] In the embodiment above, there are four apartments and the fixtures mentioned are for domestic applications. However, the system disclosed herein is not limited to such environments, for example, the building may be an office building with individual offices instead of apartments. The system is particularly suitable to situations in which there are multiple users.

[0072] In the embodiments described above, the system has been described with respect to a plurality of hot water supply pipes 14. However, it will be appreciated that the system is also applicable to a system in which there is only one hot water supply pipe 14 and the auxiliary line 50 is connected only to that hot water supply pipe 14. In such a system, some components would not be necessary. For example, the manifold 94 which distributes the heated water from the heat exchanger 72 into a plurality of branch supply pipes would not be necessary. In addition, the branching of the auxiliary line 50 into the branch supply pipes and the branch return pipes would not be necessary.

[0073] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

[0074]

Additional Clauses

Also disclosed herein is:

Clause 1. A system which maintains a temperature of a fluid in a plurality of primary lines, each primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to each primary line by a plurality of branch supply pipes and connected at a second end to each primary line by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary line; a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when a flow of fluid in the branch supply pipe or its associated primary line increases above a predetermined threshold.

2. A system according to clause 1, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in the flow rate of the fluid in the branch supply pipe or its associated primary line above a predetermined flow rate.

3. A system according to clause 1 or clause 2, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in a pressure differential between a pressure of the fluid upstream of the flow control mechanism and a pressure of the fluid downstream of the flow control mechanism above a predetermined pressure differential.

4. A system according to any one of the preceding clauses, wherein the heater is a heat exchanger and a heat source of the heat exchanger is fluid drawn from the main supply pipe.

5. A system according to any one of the preceding clauses, wherein the branch supply pipes are connected to the primary lines at a first position toward the first mains end and the branch return pipes are connected to the primary lines at a second position at the utilisation end or in the vicinity of the utilisation end.

6. A system according to any one of the preceding clauses, further comprising a pump connected to the auxiliary line for circulating fluid drawn from the primary lines via the branch return pipes through the auxiliary line and back to the primary lines via the plurality of branch supply pipes.

7. A system according to any one of the preceding clauses, comprising a housing within which each of the pump, the heat exchanger and the stop valves are housed.

8. A system according to any one of the preceding clauses, wherein a meter which measures an amount of fluid which flows from the main supply pipe into the primary line is provided in each primary line.

9. A system according to any one of the preceding clauses, further comprising an isolation valve for each branch supply pipe which is operable to stop the flow of the fluid within its respective branch supply pipe independently of the flow control mechanism.

10. A system according to clause 9, wherein the isolation valve is manually operable to stop the flow of the fluid within its respective branch supply pipe.

11. A system according to any one of the preceding clauses, further comprising a main shut off mechanism which is operable to stop the flow of the fluid through the system from the branch return pipes through the auxiliary line to the branch supply pipes.

12. A system according to clause 11, wherein the main shut off mechanism is provided on the auxiliary line.

13. A system according to clause 11 or clause 12, further comprising a timer which controls the main shut off mechanism.

14. A system according to any one of the preceding clauses, further comprising a non return valve in each branch supply pipe to prevent a flow of the fluid from the primary line associated with each branch supply pipe along the branch supply pipe.

15. A system according to any one of the preceding clauses, wherein the fluid is water.

Clause 16. A system, comprising: a plurality of primary pipes, each primary pipe having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable; an auxiliary pipe connected at a first end to each primary pipe by a plurality of branch supply pipes and connected at a second end to each primary pipe by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary pipe; a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when the flow of fluid in the branch supply pipe or its associated primary pipe increases above a predetermined level.

17. A system according to clause 16, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in the flow rate of the fluid in the branch supply pipe or its associated primary pipe above a predetermined flow rate.

18. A system according to clause 16 or clause 17, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in a pressure differential between a pressure of the fluid upstream of the flow control mechanism and a pressure of the fluid downstream of the flow control mechanism above a predetermined pressure differential.

19. A system according to any one of clauses 16 to 18, wherein the heater is a heat exchanger and a heat source of the heat exchanger is fluid drawn from the main supply pipe.

20. A system according to any one of clauses 16 to 19, wherein the branch supply pipes are connected to the primary lines at a first position toward the first mains end and the branch return pipes are connected to the primary pipes at a second position at the utilisation end or in the vicinity of the utilisation end.

21. A system according to any one of clauses 16 to 20, further comprising a pump connected to the auxiliary pipe for circulating fluid drawn from the primary pipes via the branch return pipes through the auxiliary pipe and back to the primary pipes via the plurality of branch supply pipes.

22. A system according to any one of clauses 16 to 21, comprising a housing within which each of the pump, the heat exchanger and the stop valves are housed.

23. A system according to any one of clauses 16 to 22, further comprising, in each primary pipe, a meter which measures a flow of the fluid from the main supply pipe into the primary pipe.

24. A system according to any one of clauses 16 to 23, further comprising an isolation valve for each branch supply pipe which is operable to stop the flow of the fluid within its respective branch supply pipe independently of the flow control mechanism.

25. A system according to clause 24, wherein the isolation valve is manually operable to stop the flow of the fluid within its respective branch supply pipe.

26. A system according to any one of clauses 16 to 25, further comprising a main shut off mechanism which is operable to stop the flow of the fluid through the system from the branch return pipes through the auxiliary line to the branch supply pipes.

27. A system according to clause 26, wherein the main shut off mechanism is provided on the auxiliary line.

28. A system according to clause 26 or clause 27, further comprising a timer which controls the main shut off mechanism.

29. A system according to any one of clauses 16 to 28, further comprising a non-return valve in each branch supply pipe to prevent a flow of the fluid from the primary pipe associated with each branch supply pipe along the branch supply pipe.

30. A system according to any one of clauses 16 to 29, wherein the fluid is water.

Clause 31. An assembly for maintaining the temperature of a fluid in a plurality of primary lines, the primary lines being connected to a main supply pipe, the assembly comprising: a housing which houses components of the assembly; an inlet pipe which passes through the housing and through which fluid from the primary lines flows into the assembly; a heater provided within the housing and which heats the fluid from the inlet pipe; a plurality of outlet pipes which pass through the housing and through which fluid from the heater flows out of the assembly to the primary lines; and a flow control mechanism provided for each outlet pipe which stops the flow of fluid in the outlet pipe when the flow of the fluid in the outlet pipe or its associated primary line increases above a predetermined level.

32. An assembly according to clause 31, wherein each flow control mechanism stops the flow of the fluid in response to an increase in the flow rate of the fluid in the outlet pipe or its associated primary line.

33. An assembly according to clause 31 or clause 32, wherein each flow control mechanism stops the flow of the fluid in response to an increase in a pressure differential between the fluid upstream of the flow control mechanism and a pressure downstream of the flow control mechanism above a predetermined pressure differential.

34. An assembly according to any one of clauses 31 to 33, wherein the heater is a heat exchanger and a heat source of the heat exchanger is fluid drawn from the main supply pipe.

35. A system according to any one of clauses 31 to 34, further comprising a pump for circulating fluid drawn from the primary line into the assembly via the inlet pipe through the heater and back to the primary lines via the plurality of outlet pipes.

36. An assembly according to any one of clauses 31 to 35, further comprising a distribution manifold which distributes fluid from the heater to the plurality of outlet pipes.

37. An assembly according to any one of clauses 31 to 35, further comprising an isolation valve for each outlet pipe which is operable to stop the flow of the fluid within its respective outlet pipe independently of the flow control mechanism.

38. An assembly according to clause 37, wherein the isolation valve is manually operable to stop the flow of the fluid within its respective outlet pipe.

39. An assembly according to any one of clauses 31 to 38, further comprising a main shut off mechanism which is operable to stop the flow of the fluid through the assembly.

40. An assembly according to clause 39, wherein the main shut off mechanism is provided on the inlet pipe and stops the flow of the fluid into the assembly through the inlet pipe.

41. An assembly according to clause 39 or 40, further comprising a timer which controls the main shut off mechanism.

42. An assembly according to any one of clauses 31 to 41, further comprising a non return valve in each outlet pipe which prevents a flow of the fluid from the primary pipe associated with each outlet pipe into the assembly through the outlet pipe.

43. An assembly according to any one of clauses 42 to 42, wherein a meter which measures an amount of the fluid which flows from the main supply pipe into the primary pipe is provided in each primary pipe.

44. An assembly according to any one of clauses 31 to 43, wherein the fluid is water.

Clause 45. A system which maintains a temperature of a fluid in at least one primary line, the at least one primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to the at least one primary line and connected at a second end to the at least one primary line; a heater which heats the fluid in the auxiliary line; a flow control mechanism to stop a flow of the fluid in the auxiliary line when a flow of fluid from the auxiliary line into primary line or in the primary line increases above a predetermined threshold.

Claims (20)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A system which maintains a temperature of a fluid in a plurality of primary lines, each primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to each primary line by a plurality of branch supply pipes and connected at a second end to each primary line by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary line; a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when a flow of fluid in the branch supply pipe or its associated primary line increases above a predetermined threshold.

2. A system according to claim 1, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in the flow rate of the fluid in the branch supply pipe or its associated primary line above a predetermined flow rate.

3. A system according to claim 1 or claim 2, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in a pressure differential between a pressure of the fluid upstream of the flow control mechanism and a pressure of the fluid downstream of the flow control mechanism above a predetermined pressure differential.

4. A system according to any one of the preceding claims, further comprising a pump connected to the auxiliary line for circulating fluid drawn from the primary lines via the branch return pipes through the auxiliary line and back to the primary lines via the plurality of branch supply pipes.

5. A system according to any one of the preceding claims, wherein a meter which measures an amount of fluid which flows from the main supply pipe into the primary line is provided in each primary line.

6. A system according to any one of the preceding claims, further comprising a main shut off mechanism which is operable to stop the flow of the fluid through the system from the branch return pipes through the auxiliary line to the branch supply pipes.

7. A system according to claim 6, further comprising a timer which controls the main shut off mechanism.

8. A system according to any one of the preceding claims, further comprising a non return valve in each branch supply pipe to prevent a flow of the fluid from the primary line associated with each branch supply pipe along the branch supply pipe.

9. A system, comprising: a plurality of primary pipes, each primary pipe having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable; an auxiliary pipe connected at a first end to each primary pipe by a plurality of branch supply pipes and connected at a second end to each primary pipe by a plurality of branch return pipes; a heater which heats the fluid in the auxiliary pipe; a plurality of flow control mechanisms, one flow control mechanism being provided in each branch supply pipe, the flow control mechanism in each branch supply pipe stopping a flow of the fluid in its respective branch supply pipe when the flow of fluid in the branch supply pipe or its associated primary pipe increases above a predetermined level.

10. Asystem according to claim 9, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in the flow rate of the fluid in the branch supply pipe or its associated primary pipe above a predetermined flow rate.

11. A system according to claim 9 or claim 10, wherein each flow control mechanism stops the flow of the fluid in its associated branch supply pipe in response to an increase in a pressure differential between a pressure of the fluid upstream of the flow control mechanism and a pressure of the fluid downstream of the flow control mechanism above a predetermined pressure differential.

12. A system according to any one of claims 9 to 11, wherein the branch supply pipes are connected to the primary pipes at a first position toward the first mains end and the branch return pipes are connected to the primary pipes at a second position at the utilisation end or in the vicinity of the utilisation end.

13. A system according to any one of claims 9 to 12, further comprising a pump connected to the auxiliary pipe for circulating fluid drawn from the primary pipes via the branch return pipes through the auxiliary pipe and back to the primary pipes via the plurality of branch supply pipes.

14. A system according to any one of claims 9 to 13, further comprising a non-return valve in each branch supply pipe to prevent a flow of the fluid from the primary pipe associated with each branch supply pipe along the branch supply pipe.

15. A system according to any one of claims I to 14, wherein the heater is a heat exchanger and a heat source of the heat exchanger is fluid drawn from the main supply pipe.

16. An assembly for maintaining the temperature of a fluid in a plurality of primary lines,the primary lines being connected to a main supply pipe, the assembly comprising: a housing which houses components of the assembly; an inlet pipe which passes through the housing and through which fluid from the primary lines flows into the assembly; a heater provided within the housing and which heats the fluid from the inlet pipe; a plurality of outlet pipes which pass through the housing and through which fluid from the heater flows out of the assembly to the primary lines; and a flow control mechanism provided for each outlet pipe which stops the flow of fluid in the outlet pipe when the flow of the fluid in the outlet pipe or its associated primary line increases above a predetermined level.

17. An assembly according to claim 16, wherein the heater is a heat exchanger and a heat source of the heat exchanger is fluid drawn from the main supply pipe.

18. An assembly according to claim 16 or 17, further comprising a distribution manifold which distributes fluid from the heater to the plurality of outlet pipes.

19. A system which maintains a temperature of a fluid in at least one primary line, the at least one primary line having a first mains end connected to a main supply pipe and a second utilisation end where the fluid is utilisable, the system comprising: an auxiliary line connected at a first end to the at least one primary line and connected at a second end to the at least one primary line; a heater which heats the fluid in the auxiliary line; a flow control mechanism to stop a flow of the fluid in the auxiliary line when a flow of fluid from the auxiliary line into primary line or in the primary line increases above a predetermined threshold.

20. A system according to any one of claims I to 15 and 19, wherein the fluid is water.