GB2334568A

GB2334568A - Promoting circulation in hot/chilled water supply systems

Info

Publication number: GB2334568A
Application number: GB9902384A
Authority: GB
Inventors: Neville George Ray
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-07
Filing date: 1999-02-04
Publication date: 1999-08-25
Anticipated expiration: 2019-02-04
Also published as: GB9814585D0; GB9902384D0; GB2334568B

Abstract

Circulation in the hot water pipework 24 leading from a heat exchanger 12 to a draw-off point 14a is promoted between periods of use by a small diameter pipe 32 which extends within the pipework 24 down as far as the draw-off point (Fig 4) and is connected at its other end to a pump 36. This ensures that water in the pipework stays hot. The draw-off point may be a sink, wash basin, bath, shower or appliance. As shown, hot liquid is pumped from the heat exchanger 12 via another small diameter tube housed within pipework 22, through the pump 36, into the small diameter pipe 32, and out through the open end of the pipe 32 near the draw-off point. Alternatively, flow may be in the opposite direction. Either way, the cooled standing water in the pipework 24 is returned to the heat exchanger 12. A number of pipes 32 serving different draw-off points may be connected to the same pump 36 (Figs 5, 6). The draw-off points may instead be supplied by a ring main (46, Fig 8) and circulation in the pipework (24) surrounding each small diameter pipe (32) induced by a single pump (36) in the ring main circuit. The small diameter pipes 32 may be provided with adjustable restrictor valves 34. The system may be applied to chilled water supply systems.

Description

TITLE Water Supply Systems DESCRIPTION The present invention relates to water supply systems, for example for supplying hot or chilled water to sinks, wash basins, baths, showers and appliances in domestic, commercial or industrial premises.

In particular, the invention is concerned with a water supply system comprising a heat exchanger (such as a hot water cylinder) and pipework for feeding water from a supply and through the heat exchanger to a draw-off point (such as a tap or a coupling for an appliance), the pipework including a deadleg leading to the draw-off point.

It is well known that a problem with a deadleg in the pipework of a hot-water system is that, unless water is frequently taken from the draw-off point, the water in the deadleg cools, and it is then necessary to "run the tap" for some time before the water runs hot. This wastes water and can be annoying. Several ways of dealing with this problem have been proposed in the past. For example, it is known to modify the basic system so that the deadleg forms part of a circuit in which hot water circulates under the action of gravity with a thermo-siphon effect. For a very simple system, this can be effective, but in more complex systems with several deadlegs and/or complicated pipe runs, it can be very hit or miss as to whether any effective circulation occurs. To overcome this latter problem, it is also known (see for example patent document GB-A-2226388) to include a pump to try to ensure that circulation is set up in the deadleg.

A problem caused by gravity or pumped circulation systems is that additional pipes are required in the system, and these can be unsightly and laborious to install. To deal with this problem, it is known to use special dual channel pipes, which appear on the outside to be a single pipe (see patent document US-A-4759382 for a gravity circulation example, and US-A-4628902 for a pumped circulation example). It is also known to thread a small diameter flexible pipe through a deadleg pipe to provide circulation (see patent documents US-A-4682581 and US-A-5586720 for pumped circulation examples, the latter employing a separate auxiliary heater to heat the circulating water).

The system of US-A4682581 uses a pump whose housing is fitted to the outlet at the top of a hot-water cylinder. The pump housing permits the free flow of water from the hot-water cylinder to the deadleg pipe. A flexible pipe is inserted into the deadleg pipe and is connected to the suction side of the pump inside the housing. The pressure side of the pump is open to the interior of the hot-water cylinder.

Problems associated with the system of US-A-4682581 are that: a special pump housing is required; the location of the pump is limited to being on top of the hot-water cylinder; the traditional venting of the system using a pipe run which extends vertically upwardly from the outlet of the hot-water cylinder is not possible; and adaptation of the system to deal with more than one deadleg would be complicated.

The present invention deals with the above problems by providing a small diameter pipe which extends from a first end thereof which is outside the pipework, then through the wall of the pipework at or adjacent the upstream end of the deadleg or between the heat exchanger and the deadleg, and then along the inside of the deadleg pipework, to a second open end of the small diameter pipe which is at or adjacent the draw-off point; and a pump which is connected between the first end of the small diameter pipe and the heat exchanger or the pipework adjacent the heat exchanger.

The system of the present invention therefore has the advantages that: pumped circulation is provided; the additional small diameter pipe is hidden along the run of the deadleg by being inside the deadleg pipework; a completely standard pump can be employed; the pump can be sited where desired so as to avoid cavitation and so as not to interfere with venting of the system, in the case of a hot-water system; a separate auxiliary heat exchanger is not required; and the system can be simply adapted to deal with more than one deadleg, for example by providing a respective such small diameter pipe for each deadleg and by tee-ing together the first ends of the small diameter pipes and connecting them to a common pump.

Preferably, the (or each) small diameter pipe has an (or a respective) adjustable restrictor valve therein for adjusting the circulation flow rate and, in the case of more than one deadleg, to balance the circulation flow rates.

In one embodiment of the invention, the pipework includes a ring-main extending from the heat exchanger and back to the heat exchanger; the (or each) deadleg extends from the ring-main to the (or the respective) draw-off point; the pump is provided in the ring-main between the deadleg(s) and its/their return to the heat exchanger; and the first end of the (or each) small diameter pipe is connected to the ring-main upstream of the pump. As is known, the ring-main and pump provide circulation other than in the deadleg(s), but additionally the small diameter pipes provide(s) circulation in the deadleg(s) and utilise the same pump.

The outlet of the pump may be connected to the pipework on the inlet side or the outlet side of the heat exchanger, or by a separate connection. m the case where a hotwater cylinder or a chilled-water cylinder is used as the heat exchanger, the pipe from the pump preferably enter a short distance into the interior of the cylinder.

To facilitate installation, the (or each) small diameter pipe is preferably flexible.

The (or each) small diameter pipe preferably extends through the wall of the pipework at a (or a respective) coupling, the (or each) coupling comprising: a hollow body having first and second bores (for example of equal diarneter) to receive first and second pipes of the pipework and a third bore to receive the small diameter pipe; and means for sealing the first and second pipes and the small diameter pipe to the hollow body. Preferably, the first and second bores are shouldered to limit the extent to which the first and second pipes can be inserted thereinto, while the third bore is unshouldered so that the small diameter pipe can be inserted therethrough and into the first pipe.

The means for sealing the small diameter pipe to the hollow body may comprise a compression or push-fit joint, or alternatively a sleeve of heat-shrink material, the sleeve having a first portion which is heat-shrunk around a portion of the hollow body surrounding the third bore, and a second portion which is heat-shrunk around the small diameter pipe.

In one embodiment, the first and second bores are mutually aligned so as to provide a straight coupling of the first and second pipes, and the third bore is inclined at an obtuse angle to the first bore so as to facilitate insertion of the small diameter pipe into the first pipe. In another embodiment, the first and third bores are mutually aligned so as to facilitate insertion of the small diameter pipe into the first pipe, and the second bore is at right angles to the first bore so as to provide an elbow coupling of the first and second pipes.

Specific embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a first embodiment of a hot-water supply system; Figure 2 is a longitudinally-sectioned view of a pipe coupling used in the system of Figure 1; Figure 3 is a longitudinally-sectioned view of another part of the system of Figure 1; Figure 4 is a side view, partly sectioned, of the end of one of the deadlegs and one of the draw-off points in the system of Figure 1; Figure 5 shows a first modification to part of the system of Figure 1; Figure 6 shows a second modification to part of the system of Figure 1; Figure 7 is a longitudinally-sectioned view of a pipe coupling used in the system of Figure 6; and Figure 8 is a schematic diagram of a second embodiment of the system.

Referring to Figure 1 a hot-water supply system comprises a cold-water cistern 10, an indirect hot-water cylinder 12, a number of draw-off points 14a,b (taps), and pipework connecting them together. The pipework includes: a cold-water supply pipe 16 feeding water from the water main to a float valve 18 in the cold-water cistern 10; a cold-water supply pipe 20 extending from the cold-water cistern 10 to the hotwater cylinder 12; and a shared hot-water pipe 22 extending from the hot-water cylinder 12 to (a) a deadleg pipe run 24 feeding the draw-off points 14a,b, and (b) an expansion pipe 26 which rises to a level above the normal water level in the cold-water cistern 10.

As described so far with reference to Figure 1, the system is conventional. The water in the hot-water cylinder is heated by a coiled heater pipe 29 connected to a boiler, or by an immersion heater. When one of the draw-off points (say draw-off point 14b) is opened, hot water flows from the hot-water cylinder 12 and through the shared pipe 22 and deadleg pipe run 24 to that draw-off point 14b. However, if the water in the deadleg pipe run is not initially hot, there will be a delay before the hot water reaches the drawoff point 14b.

In order to deal with this, the conventional system is modified in the following way. A pair of couplings 28 as shown in Figure 2 are fitted into the deadleg pipe run 24 adjacent the shared pipe 22 (i.e. adjacent its upstream end). Each coupling 28 is an unequal compression tee having a straight-through connection for the deadleg pipe run 24, and a branch 30 which is inclined at an obtuse angle (say 135 ) to the straightthrough connection. The compression fittings for the portions of the deadleg 24 are shouldered in a conventional way and are sized to receive standard size pipe, e.g. 15rnm, 22mm or 28mm outside diameter. The compression fitting of the branch 30 is, however, not shouldered and is sized to receive a smaller diameter pipe, e.g. 6mm, 8mm or 10mm outside diameter. A flexible pipe 32 is inserted into the branch 30 of the downstream coupling 28 and is threaded along the downstream portion of the deadleg 24 so that its far end is adjacent the draw-off point 14b at the downstream end of the deadleg pipe run 24, as shown for example in Figure 4. To assist in such threading (especially if the flexible pipe 32 is fitted after installation of the deadleg pipe run 24 has been completed), any elbows in the downstream portion of the deadleg 24 are preferably of the "slow" type, and any tees preferably provide a straight-through connection towards the most downstream of the draw-off points 14b. The other end of the flexible pipe 32 is connected, via an adjustable restrictor valve 34, to the pressure side of a pump 36. The suction side of the pump 36 is connected via an isolation valve to a further small diameter flexible pipe 38 which enters the the deadleg via the upstream coupling 28 and is threaded through the shared pipe 22 and into the hot-water cylinder 12 so that its end 40 is inside the hot-water cylinder 12, as shown in Figure 3.

In use, and with both of the draw-off points 14a,b closed, the pump causes a circulation of hot water which passes: from the hot-water cylinder 12, through the flexible pipe 38 which passes to the outside of the deadleg 24 through the upstream coupling 28, through the pump 36, through the restrictor valve 34, through the flexible pipe 32, which enters into the deadleg 24 at the downstream coupling 28, to the far end of the flexible pipe 32 adjacent the draw-off point 14b, through the deadleg 24 on the outside of the flexible pipes 38,32, through the shared hot-water pipe 22 on the outside of the flexible pipe 38, and back into the hot-water cylinder 12.

It will therefore be appreciated that the water in the deadleg pipe run 24 is kept hot, and when either of the draw-off points 14a,b is opened, hot water is instantly (or almost instantly) available.

It will be appreciated that the system described above (a) results in the flexible pipe 28 being hidden along most of its length by being threaded through the downstream portion of the deadleg 24, (b) does not interfere with the run of the shared pipe 22 and expansion pipe 26, (c) provides flexibility as to the siting and orientation of the pump 36 whereby cavitation in the pump can be avoided, (d) enables a completely standard pump 36 to be used, and (e) is readily adaptable to cope with additional deadlegs, merely by adding a further coupling 28 and flexible pipe 32 into each additional deadleg, and teeing the additional flexible pipe 32 via a respective restrictor valve 34 in with the existing one 32 immediately downstream of the pump 36, as shown by the modification of Figure 5.

It will also be appreciated that many other modifications and developments may be made to the system described above. For example, the direction of the pump and the direction of circulation could be reversed. Also, the flexible pipe 38 on the suction side of the pump 36 could lead into the hot-water cylinder 12 via a coupling 28 in the coldwater supply pipe 20, rather than the shared hot-water supply pipe 22 (especially if the circulartion direction is reversed), or indeed via a completely separate fitting on the hot water cylinder 12. Furthermore, the techniques described above may be applied to chilled-water systems, rather than hot-water systems.

Also, as shown in Figure 2, the coupling 28 provides a straight-through connection for the deadleg, with the branch 30 for the flexible pipe 32 being obtusely inclined to the downstream portion of the deadleg 24. Instead of this, the coupling 28 could provide an elbow (for example a right-angled elbow) for the deadleg, with the branch 30 for the flexible pipe 32 being aligned with the downstream portion of the deadleg 24. In this case, the downstream coupling 28, for example, could be employed at the location 42 shown in Figure 1. Alternatively, as shown in Figure 7, the coupling 28 could be configured as an 'x', rather than a tee, providing three connections for the larger diameter pipes, and the fourth connection being for the small diameter pipe 32.

In this case, such couplings 28 could be employed as shown by the modification of Figure 6.

Furtherrnore, although the couplings 28 shown in Figures 2 and 7 use compression fittings for all of the pipes, other ways of sealing the pipes to the body of the coupling 28 may be employed, such as push-fit for any of the pipes and Yorkshire or end-feed solder connections for the deadleg pipework 24 if it is of copper. Moreover, in order to seal the flexible pipe 32 to the body of the coupling 28, a sleeve of heatshrinkable material may be used with part of the sleeve located over the branch 30 of the coupling and part of the sleeve placed over the flexible pipe 32 where it exits the branch.

When heat is applied to the sleeve, it shrinks down onto the branch 30 and shrinks down even more onto the flexible pipe 32 so as to form the seal between the two.

A second embodiment of the system will now be described with reference to Figure 8, in which the same reference numerals are used for those parts of the system which have already been described with reference to Figures 1 to 7. The following description relates to the differences of the system of Figure 8.

Unlike Figures 1 to 7 in which the deadleg(s) 24 is/are tee-ed into the shared pipe 22, in Figure 8, a hot-water ring-main pipe 46 is tee-ed into the pipe 22, and various deadlegs 24 (three of which are shown) are tee-ed into the ring-main pipe 46. As is already known, circulation is provided for in the ring-main pipe 46 by returning it to a separate coupling 48 on the hot-water cylinder 12 via a restrictor valve 50, pump 36 and isolation valve 52. However, such a known system does not provide for circulation in the deadlegs 24. In order to achieve this, arrangements of couplings 28 as shown in Figure 7, flexible pipes 32 and restrictor valves 34 similar to those described with reference to Figures 1 to 7 are employed, but with the restrictor valves 34 being connected to a common small-diameter pipe 54 which is in turn connected via a restrictor valve 56 to the suction side of the pump 36.

The system of Figure 8 may be modified in similar ways to those described above with reference to Figures 1 to 7.

It should be noted that the embodiments of the invention have been described above purely by way of example and that many other modifications and developments may be made within the scope of the invention.

Claims

CLAIMS 1. A water supply system, comprising: a heat exchanger; pipework for feeding water from a supply and through the heat exchanger to a draw-off point, the pipework including a deadleg leading to the draw-off point; a small diameter pipe extending from a first end thereof which is outside the pipework, then through the wall of the pipework at or adjacent the upstream end of the deadleg or between the heat exchanger and the deadleg, and then along the inside of the deadleg pipework, to a second open end of the small diameter pipe which is at or adjacent the draw-off point; and a pump connected between the first end of the small diameter pipe and the heat exchanger or the pipework adjacent the heat exchanger.
2. A system as claimed in claim 1, wherein the pipework includes a plurality of such deadlegs, each having a respective such small diameter pipe.
3. A system as claimed in claim 2, wherein the pump is common to each of the small diameter pipes.
4. A system as claimed in any preceding claim, wherein the (or each) small diameter pipe has an (or a respective) adjustable restrictor valve therein.
5. A system as claimed in any preceding claim, wherein: the pipework includes a ring-main extending from the heat exchanger and back to the heat exchanger; the (or each) deadleg extends from the ring-main to the (or the respective) drawoff point; the pump is provided in the ring-main between the deadleg(s) and its/their return to the heat exchanger; and the first end of the (or each) small diameter pipe is connected to the ring-main upstream of the pump.
6. A system as claimed in any preceding claim, wherein the outlet of the pump is connected to the pipework on the inlet side of the heat exchanger.
7. A system as claimed in any of claims 1 to 5, wherein the outlet of the pump is connected to the pipework on the outlet side of the heat exchanger.
8. A system as claimed in any of claims 1 to 5, wherein the outlet of the pump is connected by a separate coupling to the heat exchanger.
9. A system as claimed in any preceding claim, wherein the heat exchanger is a hotwater cylinder or a chilled-water cylinder.
10. A system as claimed in any preceding claim, wherein the (or each) small diameter pipe is flexible.
11. A system as claimed in any preceding claim, wherein the (or each) small diameter pipe extends through the wall of the pipework at a (or a respective) coupling, the (or each) coupling comprising: a hollow body having first and second bores to receive first and second pipes of the pipework and a third bore to receive the small diameter pipe; and means for sealing the first and second pipes and the small diameter pipe to the hollow body.
12. A system as claimed in claim 11, wherein the first and second bores are shouldered to limit the extent to which the first and second pipes can be inserted thereinto, the third bore being unshouldered so that the small diameter pipe can be inserted therethrough and into the first pipe.
13. A system as claimed in claim 11 or 12, wherein the means for sealing the small diameter pipe to the hollow body comprises a compression or push-fit Joint.
14. A system as claimed in claim 11 or 12, wherein the means for sealing the small diameter pipe to the hollow body comprises a sleeve of heat-shrink material, the sleeve having a first portion which is heat-shrunk around a portion of the hollow body surrounding the third bore, and a second portion which is heat-shrunk around the small diameter pipe.
15. A water supply system, substantially as described with reference to the drawings.

15. A system as claimed i2 any of claims 11 to 14, wherein the first and second bores are of equal diameter.
16. A system as claimed in any of claims 11 to 15, wherein the first and second bores are mutually aligned, and the third bore is inclined at an obtuse angle to the first bore.

17. A system as claimed in any of claims 11 to 15, wherein the first and third bores are mutually aligned, and the second bore is at right angles thereto.

18. A water supply system, substantially as described with reference to the drawings.

Amendments to the claims have been filed as follows 1. A water supply system, comprising: a heat exchanger; pipework comprising a first pipe run for feeding of water from a supply to the heat exchanger and a second pipe run, including a deadleg leading to a draw-off point, for feeding of the water from the heat exchanger to the draw-off point; a first small diameter pipe extending from a first end thereof at the heat exchanger, then along the inside of the second pipe run to a point part-way therealong, and then through the wall of the second pipe run to a second end thereof outside the second pipe run; a second small diameter pipe extending from a first end thereof inside the second pipe run at or adjacent the draw-off point, then along the inside of the second pipe run to point part-way therealong, and then through the wall of the second pipe run to a second end thereof outside the second pipe run; and a pump connected between the second ends of the first and second small diameter pipes.

2. A system as claimed in claim 1, wherein the pipework includes a plurality of such deadlegs, each having a respective such second small diameter pipe.

3. A system as claimed in claim 2 wherein the pump is common to each of the second small diameter pipes. 4. A system as claimed in any preceding claim, wherein at least one of the small diameter pipes has an adjustable restrictor valve therein 5. A system as claimed in any preceding claim, wherein the heat exchanger is a hotwater cylinder or a chilled-water cylinder.

6. A system as claimed in any preceding claim, wherein each of the small diameter pipes is flexible.

7. A system as claimed in any preceding claim, wherein each of the small diameter pipes extends through the wall of the second pipe run at a respective coupling, each coupling comprising: a hollow body having first and second bores to receive respective pipes of the second pipe run and a third bore to receive the small diameter pipe; and means for sealing the pipes of the second pipe run and the small diameter pipe to the hollow body.

8. A system as claimed in claim 7, wherein the first and second bores are shouldered to limit the extent to which the respective pipes of the second pipe run can be inserted thereinto, the third bore being unshouldered so that the small diameter pipe can be inserted therethrough and into one of those pipes of the second pipe run.

9. A system as claimed in claim 7 or 8, wherein the means for sealing the small diameter pipe to the hollow body comprises a compression or push-fit joint.

10. A system as claimed in claim 7 or 8, wherein the means for sealing the small diameter pipe to the hollow body comprises a sleeve of heat-shrink material, the sleeve having a first portion which is heat-shrunk around a portion of the hollow body surrounding the third bore, and a second portion which is heat-shrunk around the small diameter pipe.

11. A system as claimed in any of claims 7 to 10, wherein the first and second bores are of equal diameter.

12. A system as claimed in any of claims 7 to 11, wherein the first and second bores are mutually aligned, and the third bore is inclined at an obtuse angle to the first bore.

13. A system as claimed in any of claims 7 to 11, wherein the first and third bores are mutually aligned, and the second bore is at right angles thereto.

14. A system as claimed in claim 13, wherein the hollow body has a fourth bore aligned with the second bore to receive a further pipe of the second pipe run.