GB2234294A

GB2234294A - Temperature control and valve means in a water supply arrangement

Info

Publication number: GB2234294A
Application number: GB8915655A
Authority: GB
Inventors: Robert Leitch Rivers
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-07-07
Filing date: 1989-07-07
Publication date: 1991-01-30
Also published as: GB8915655D0

Abstract

A temperature sensing device 14 is positioned in an outlet from the mixing device 10 and in the event that the temperature in the outlet rises above a predetermined temperature a water supply pump is switched off. A one-way mechanical valve 15 is located in the hot water supply and when the pump is switched off, the valve moves to block the supply of hot water. Preferably the valve has a bias spring (23, Fig. 2) which acts, in the absence of a net external pressure on the valve, to close the valve. <IMAGE>

Description

Improvements in and Relating to a Pumped Hot Water Supply The present invention relates to the supply of hot water and more particularly to an arrangement for preventing water above a predetermined temperature being supplied to a user of a pumped hot water supply system.

The invention will be described in relation to its use in a shower for domestic purposes but it will be appreciated that the apparatus has many other uses.

It is known to provide pumped hot water supplies with temperature control arrangements whereby any desired temperature can be assured. This usually requires a complex arrangement utilising either bimetallic valve members or electrically controlled valves for controlling the relative proportions of hot and cold water supplied to a mixing device.

It is also known to provide a so-called "antiscald " device which operates as a limit switch and actually substantially terminates supply of hot water usually by activating an electro-mechanical valve in the hot water supply and switching off the pump. While this is effective, it is expensive.

It is an object of the present invention to provide an arrangement which will inhibit or substantially inhibit flow of hot water in response to detection of water of a predetermined temperature in a simple and inexpensive manner.

The present invention provides a water supply arrangement comprising a pump, a mixing device arranged to be connected to hot and cold water supplies, a temperature detection device for detecting the temperature of water supplied from the mixing device, and mechanical one-way valve in the hot water supply, the detection device being operable to switch off the pump.

Preferably, the one-way valve is biased to a normally closed position in any convenient manner eg a spring. More importantly, the down stream side of the valve is preferably subjected to water from the cold water supply which is consequently at the pressure of the cold water supply.

It will be appreciated that in this arrangement a mechanical shut off valve need only be located in the hot water supply. There is no need for a shut off valve in the cold water supply and in fact the system operates at its best when there is no shut off valve in the cold water supply.

Features and advantages of the present invention will become apparent from a description of an embodiment thereof given by way of example with reference to the accompanying drawings, in which: Fig. 1 shows an arrangement according to the present invention; Fig. 2 shows a cross sectional side view of a one-way valve of a type useful in the present invention.

The preferred embodiment of the present invention is an arrangement for a domestic shower which is fitted with an anti-scald device which prevents hot water at its maximum temperature from being discharged on a user. The device must act quickly and be reliable in operation even after an extended period of non-use.

Referring now to Fig. 1, this shows diagrammatically a mixer valve (10) provided with an inlet (11) for connection to a hot water supply, an inlet (12) for connection to a cold water supply and an outlet (13). A temperature sensor (14) is located at a position to detect outlet water temperature, in this case by being located in the outlet (13).

A one-way valve (15) is located in the hot water supply line to the mixer valve (10). Preferably, the valve (15) is located in the inlet (11) of the mixer valve. The location of the valve (15) is not critical as long as the down stream side of the valve can be subjected to pressure from the cold water supply.

A pump (not shown) is connected either to the outlet (13) from the mixer valve (10) or to the inlets (11, 12).

In operation, when the temperature sensor detects hot water at is maximum temperature, it causes the pump to switch off. This, however, is not sufficient in itself to completely terminate supply of water to the outlet as the hot and cold water supplies are usually fed to the mixer valve under the effect of gravity as well as being pumped. The one-way valve (15) is therefore provided to positively shut off the hot water supply. We have found that a simple mechanical one-way valve (15) is sufficient for this purpose as long as the down stream side of the valve (15) can be subjected to the pressure of the cold water supply. The operation of the valve (15) will be described in more detail with reference to Fig. 2 which shows a third form of the valve.

The valve (15) is located at an appropriate position in the hot water supply with the direction of water flow indicated by the arrow A. The valve (15) comprises a generally tubular body (12) provided with a valve seat portion (21) arranged to receive a valve member (22) eg a bowl of a suitable material such as glass. The valve (15) is a normally closed valve with the valve member (22) held against the valve seat (21) by a biasing force provided in this case by a spring (23).

Under normal operating conditions, the pump causes a pressure differential to exist across the valve of a magnitude sufficient to overcome the spring force and thus cause the bowl (22) to lift off the valve seat (21) thereby permitting flow of hot water through the tubular body (20). When the temperature sensor (14) operates, the pump is switched off. This may be sufficient, alone, to cause the valve to close under the action of the spring (23). However, for domestic showers, it is considered that a spring force sufficient to close the valve (15) under all normal domestic water supply pressures would introduce too high a constriction. It is therefore preferred to use a very small spring force eg of the order of half p.s.i. or even less and utilise the pressure of the cold water supply acting on the valve (15) in the same direction and the spring (23). It will be appreciated that to a first approximation, in the absence of the spring force the pressures across the valve (15) due to the hot and cold water supplies will be balanced and hence only a very small spring force will be required to close the valve.

The use of the cold water pressure to assist in closing the valve also has the advantageous effect that cold water is continuously fed to the mixer valve under the action of gravity and this in turn means that cold water is supplied to the temperature sensor (14) at the outlet of the mixer valve which resets much more quickly than would be the case if the water supply from both the hot and cold inlet were positively terminated.

Claims

CLAIMS:

1. A water supply arrangement comprising a mixing device arranged to be connected to hot and cold water supplies, a pump arranged to assist the flow of water, a temperature detection device arranged to detect the temperature of water supplied from the mixing device and a mechanical one-way value in the hot water supply, wherein the temperature detection device is operative to switch off the pump in the event that the temperature of water supplied from the mixing device rises above a predetermined temperature.

2. A water supply arrangement as claimed in claim 1 wherein the pump is situated in the outlet from the mixing device.

3. A water supply arrangement as claimed in claim 1 wherein the pump is arranged to assist the flow of both the hot and cold inlets.

4. A water supply arrangement as claimed in any preceding claim wherein the mechanical valve comprises a spring, said spring being operative to shut the valve in the absence of a net external pressure on the valve.

5. A water supply arrangement as claimed in claim 4 wherein said spring applies a pressure of 0.5 p.s.i.

6. A water supply arrangement as claimed in any preceding claim wherein the mechanical valve is located in the hot water supply adjacent to the mixing device.

7. A water supply arrangement substantially as hereinbefore described with reference to the accompanying drawings.