GB2227296A

GB2227296A - Hot water cut-off valve

Info

Publication number: GB2227296A
Application number: GB8927033A
Authority: GB
Inventors: James David Coleman; Anthony Gregory Smith
Original assignee: S & C Thermofluids Ltd
Current assignee: S & C Thermofluids Ltd
Priority date: 1988-12-02
Filing date: 1989-11-29
Publication date: 1990-07-25
Also published as: GB8828113D0; GB8927033D0

Abstract

In situations where it is desirable to mix an independent supply of substantially low pressure hot water with an independent supply of substantially high pressure cold water, failure of the cold supply could cause a scalding temperature blended flow to result. The present invention provides a valve having a closure member 13 which controls the flow of hot water and which closes to cutoff such flow in response to the reduction below a predetermined level of the flow of cold water. One embodiment of the invention also incorporates an integral non-return valve on the hot supply. <IMAGE>

Description

HOT WATER CUT-OFF VALVE This invention relates to a hot water cut-off valvt- operated by cold water.

Until recently, the Model Water Bye-laws have prevented the blending of stored, tank fed hot water with main fed cold water.

The regulations have changed now and it is permissible to allow blending so long as precautions are taken to prevent the back-flow of either supply into the other. Means by which this can be achieved include non-return valves commonly known in the water industry as double-check valves.

So long as these precautions are taken, there are instances when it may be wished to blend a high pressure mains cold supply with a stored hot supply. One particular instance would be in a domestic shower.

If a device were being operated under these conditiluls, it is quite possible that the stored hot water would be at scalding temperatures before being blended. If a failure were to occur on the cold mains flow it would be possible for the user to become scalded by the uninterrupted hot flow. The n(ed arises for a device which is sensitive to cold mains pressure that is able to prevent the flow of hot water when the (old mains pressure falls below a certain level.

The need to prevent the passage of hot flow is not imited to the above instance, there may be other situati > )ns in a plumbing context where the device is required to prevent the flow of any hot supply, whether it be high or low pressure.

The newly accepted high-pressure hot water systems fall into this category.

The device which is primarily envisaged to work from a cold water main could also work from any other water supply such as that created by a mechanical booster pump. An instance where this application becomes appropriate is in the pumped shower context.

In essence, the path of the hot water can be interrupted hy mechanical means. The control offered on this mechanical method is via the cold water pressure. At acceptalie. levels of cold water pressure, the path of the hot water is open.

When the cold supply is no longer sufficient to maintain an opening force, the hot path is obstructed.

According to the present invention, there is provided a hot water cut-off valve comprising a generally hollow body with a piston seal arrangement.

A prototype construction according to the invention is more particularly described with reference to the accompanying drawings wherein: Figure 1 is a schematic sectional elevation of a basic cutoff unit and Figure 2 is another presently preferred construction.

Referring now to the drawing, Figure 1, a section is shown of an axisymmetric version of the unit which comprises 8 main parts; these being the outer body 1, the hot inlet port 2, the cold inlet port 3, the hot sealing plug 4, the cold piston 5, the interconnecting rod 6, a return spring 7, and an "o ring 8.

Cold water is connected to the cold inlet port 3. When pressure is applied, the piston 5, slides to the left, compressing the spring 7. The piston 3, and plug 4, are connected by the rod 6. When motion of the piston occurs, the hot supply is enabled to flow by the displacement of the sealing plug 4. The piston 5, seals against the "o" ring 8, to prevent seepage of cold to hot when it has travelled fully. The spring 6, may be of various rates and pretensioned as required to allow for operating conditions.

In Figure 2.

Hot water flows into the unit via duct 9. Cold water is admitted to the unit via a peripheral passageway 10. Cold pressure causes the scald piston 11, to move against the spring 12, which maintains a closure force when the cold pressure is removed. Once the scald piston 11, has moved to the right, the non-return valve 13, is able to move off the seat 14, and to allow the passage of hot water. Live seals 15, are installed to prevent cross flow of supplies. Hot water exits through the peripheral passageway 16.

In the embodiment of Figure 2, it can be seen that the unit is able to offer two functions. First, when the scald piston 11 is actuated, Ie. moved to the right, the non-return valve 13, will act as a normal non-return valve. However, when the cold pressure falls below that required to keep the scald piston actuated, then the device will act as an anti-scald valve with the hot flow being cut off.

In Figure 1, it will be noted that the hot water pressure acts to close the hot valve 4. In Figure 2, it will be seen that the hot water pressure acts against closure of the valve 13.

Claims

Claims:

What we claim is: 1) A unit in which the flow of one supply of water through said unit is controlled by the action of a second independent supply of water.
2) A unit according to claim 1 in which the supply to be controlled is substantially hot and the controlling supply is substantially cold.
3) A unit, according to claim 2, in which an increasing pressure of hot water will act in addition to the closure force of the anti-scald spring.
4) A unit according to claim 2 in which an increasing pressure of hot water will act against the closure force of the anti-scald spring.
5) A unit substantially as described herein and as shown in Figure 1.
6) A unit substantially as described herein and as shown in Figure 2.
7) A shower assembly comprising: hot water supply means; cold water supply means; an anti-scald unit coupled to the hot and cold water supply means; a mixer unit; coupled downstream of the anti-scald unit; and a shower head coupled to the mixer unit to receive and discharge mixed water from it; wherein the anti-scald unit is arranged so that the cold water from the cold water supply means controls the hot water from the hot water supply means to the mixer unit.