IE20030074A1 - Time delay water heater device - Google Patents

Abstract

A method of controlling a flow of water in a water heater device, the method comprising the steps of, supplying power to a water valve being configured to control the input of water to the device the valve being operable in a first mode of operation to allow the flow of water through the device, heating the flow of water in the device using a heating element, and in response to a termination of power to the flow controller, the flow controller switching from the first mode of operation to a second mode of operation to terminate the flow of water through the device, wherein the flow controller is configured to switch from the first mode to the second mode following a finite time delay. <Figure 3>

Description

Field of the Invention The present invention relate particularly, although not exclusivel time delay water shut off valve wl power. lb lb Background to the Invention In order to provide heated water for private and industrial sanitary purposes, it is known to use an electric instantaneous electric water heater device which intakes cool water and outputs heated water. Water enters the water heater device, is heated by a heating, element inside the water heating device, and exits the water heating device via an outlet. It is known in the art to incorporate an electric water heater device within an electric shower unit as illustrated in Fig. 1. Electric water heating devices for electric showers comprise a housing vessel having an inlet, an outlet and a chamber containing an electric heating element. Water passing though the chamber is heated by the electric heating element. Typically, a shower unit 100 is mounted onto a suitable wall 101 within a shower cubical. The water heater device is located within the main body of the shower unit 100 whereby a user selects the temperature of water output by the device using a suitable temperature controller 102.

When a user turns off the shower unit using a suitable button or switch 103 on a casing of the shower unit, the water heater device continues, for a finite time period, to allow a flow of water. This continued flow of water through the heating chamber is controlled electrically and requires the supply of electricity to a solenoid which keeps open a shut-off valve on the inlet side of the housing vessel. Effectively, when a user selects to shut down the shower unit 100 an electrically controlled shut down process is initiated to allow the energy stored as heat, within the heating chamber to dissipate through the controlled and P0963.spec -2continued flow of water. Normally, when the shower is turned off, the electrical power is turned off, and a solenoid connected to the input to the housing vessel shuts down the flow of water into the chamber. However, the electric power to the solenoid is maintained for a predetermined time delay, which allows a predetermined amount of water to flow through the chamber, before water flow ceases. This allows water to flush through the chamber, dissipating any stored heat energy in the element, before the water flow through the chamber is terminated. There is a separate control circuit within the shower unit, which deactivates a predetermined delay period after activation of the ‘off’ switch on the shower casing, before activating the solenoid to cause the water valve to shut down the water flow.

However, there are conditions under which the shower unit can be turned off without the user pressing the ‘off’ switch on a casing of the shower unit. For example, if a master switch to the main supply is provided, for example fitted in the ceiling of a bathroom and operated by a draw cord, the whole power supply to the shower unit can be cut off at once. Also, under conditions of unexpected power cut to the main electric supply, the whole power supply to the shower can be terminated instantaneously. Under these conditions, the electrical control circuit which operates the predetermined delay time before shutting off the solenoid cannot operate, because it has no electric power. Therefore, under these conditions water flow through the chamber terminates at the same time as power is cut to the heater element, and there is no period of water flow after termination of the electricity to the water heater element, to allow that heat energy to dissipate outside of the water heating device by flow of water. The stored water in the heating chamber can over heat, causing the heater device to trip out, and requires a service call from an engineer to reset the device.

Fig. 2 illustrates various problems associated with prior art electrical shower units having an electrically controlled water shut-off process. At stage 200, the shower is operational providing heated water, with a heating element within a heating chamber being controlled electrically. The water in the shower unit is P0963.spec -3heated at stage 201, as it continues to pass through the housing and over the heating element. At stage 202 the electricity supply to the shower unit is lost or cut off, for example, as a result of a power cut to part of a building containing the shower unit. Without the supply of electricity to the shower unit, and consequently to the control circuit for the shut off valve the shower unit cannot shut down properly at stage 203. Instead of the electrically controlled shut down, whereby water is allowed to flow through the device to dissipate the stored energy, the supply of coo) water to the chamber is terminated at stage 204. A consequence of the loss of power to the device, and consequently the failure of io the shower unit to shut down properly, allows stored energy in the heating element to continue to heat the water within the chamber at stage 205. The continued heating of water in a closed environment within the shower unit may provide that the water heater device will trip and cut out at stage 206. An engineer would then be required to service the device to allow future use.

Summary of the Invention The inventor has realised a need for a shower unit, incorporating a water heater device, which allows the continued supply of water to flow through the 0 device in the event of loss of electricity or power to the whole shower unit. The inventor has realised that what is required is a water heater device capable of automatically allowing the continued flow of water for a period after the showerunit is turned off however that occurs, without the need for the supply of electricity or power to the device to control the shut down process.

The inventor has devised a method of controlling the flow of water in a water heater device for a shower unit after termination of electrical power to the shower unit. The method allows a continued flow of water through the water heater device in the event of loss of electrical power to the shower unit and/or the 0 water heater device forming part of the shower unit.

P0963.spec -4Controlling the flow of water to a water heater device permits the continuous flow of water through the water heater device for a finite time period following a loss of electric power to the device. The amount of water flowing through the device is designed to be sufficient to allow stored heat energy within a heating element of the device to dissipate and is controlled by the duration of a time delay to a valve, which occurs before closure of the valve. The stored heat energy in the heating element, following the loss of power to the device, is transferred to the flowing water, this water being transported out of the device.

In various implementations according to the present invention, a shut-off valve regulates the flow of water through an electric water heater device, when a power supply to the electric water heater device is terminated. The valve continues to maintain a flow of water through the electric water heater device for a predetermined period, and after the predetermined period, terminates flow of water to the water heater device. The predetermined period is not dependent upon the valve continuing to receive an electric power supply Following the loss of electrical power to the water heater device the valve remains open, allowing the passage of water. Following a finite time period, the valve closes So as to terminate the flow of water through the device. In the best mode, cut off of the flow of water after the predetermined period is actuated, both mechanically and by water pressure. The duration of the predetermined period is controlled mechanically and/or by water pressure.

One example of a shut-off valve according to a specific implementation of the present invention, comprises a solenoid having a diaphragm, such that the diaphragm is sensitive to pressure on a first side and a second side and is configurable to switch between an open and closed mode of operation in response to a difference in a water pressure value on the first side of the diaphragm relative to a water pressure value on the second side of the diaphragm.

P0963.spec -5The water heater device according to a specific implementation of the present invention has a shut down mode whereby water continues to flow through the device in the event of power loss, and is also configured to provide water flow when a supply of electrical power to the whole shower unit is present.

According to a first aspect of the present invention there is provided an electric water heater device, said device comprising: a water heater unit; a water shut-off valve for controlling a flow of water to said water heater unit; said..water. shut-off valve having a first mode of operation in which it allows a flow of water through said water heater unit, and a second mode of operation, in which it prevents flow of water to said water heater unit, said valve being configured to switch between said first mode of operation and said second mode of operation in response to a termination of electrical power; said water shut-off valve operable in use to provide a time delay between said first mode of operation and said second mode of operation, said time delay operating without the need for electrical power.

According to a second aspect of the present invention there is provided a method of controlling a flow of water through a water heater device, said method comprising the steps of: supplying power to a shut-off valve configured to control said flow of water through said device; P0963.spec -6channelling said flow of water through said shut-off valve, said shut-off valve being operable in a first mode of operation to allow said flow of water through said device; heating said flow of water in said device using a heating element; and in response to a termination of power to said shut-off valve, said shut-off valve switching from said first mode of operation to a second mode of operation to terminate said flow of water through said device; wherein said shut-off valve is configured to switch from said first mode to said second mode following a finite time delay.

According to a third aspect of the present invention there is provided a method of operating an electric shower unit capable of heating water, said shower unit comprising: a water heater device for heating a flow of water; and a water shut-off valve positioned to control input of water into said heating device; said method comprising: applying an electric signal to said water shut off valve, said electrical signal maintaining said water shut off valve in a first mode of operation, in which said shut off valve permits flow of water there through, and into said heater device; 0 on termination of said electrical signal to said water shut-off valve, said water shut-off valve operating in a third mode of operation, in which said valve waits a predetermined period of time, and during said predetermined period of P0963.spec -7time maintains an open position; and after said predetermined time period, said water valve operates in a second mode of operation, in which said water valve closes to shut off said supply of water to said heater device.

Further features and aspects of the present invention are as recited in the claims herein.

Brief Description of the Drawings For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Fig. 1 -illustrates -a typical wall mounted electric shower unit known in the prior art; Fig. 2 illustrates a flow diagram detailing the problems associated with typical electrically operated shower units known in the prior art during cut off of electrical power supply to the shower unit; Fig. 3 illustrates schematically a water heater device incorporated in a shower unit according to a specific implementation of the present invention; Fig. 4 illustrates schematically a solenoid shut-off valve controlling flow of water to a water heater device, according to a specific implementation of the present invention; Figs. 5 and 6 illustrate schematically an overview of operational modes of a shower unit according to a specific implementation of the present invention; and P0963.spec -8Fig. 7 illustrates selected components of the shower unit according to a specific implementation of the present invention having a water shut-off valve and a water heater device comprising a housing vessel containing a heating element.

Detailed Description of the Best Mode for Carrying Out the Invention There will now be described by way of example the best mode contemplated by the inventors for carrying out the invention. In the following description numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.

Fig. 3 illustrates an instantaneous electric water heater device incorporated within an electric shower unit 300 according to a specific implementation of. the present invention. The water heater device comprises a heating can comprising a housing vessel 301 having a heating chamber configured to house a heating element 302; a flow controller 303 for controlling a rate of volume of water flowing through the heater can; a solenoid actuated water shut-off valve 304 opening to allow flow of water into the heater can or closing to shut off the flow of water into the heater can as appropriate; a water inlet 305; and a water outlet 306. Power is supplied to the shower unit and the water-heater device using an external power supply wiring 307. The flow of water to the water heating device is controlled by a user of the shower unit using suitable control means 308 being connected to the flow controller 303.

The water supply to the water heater is also controlled by the water shut off valve 304. Water flowing into the heating chamber is channeled through flow controller 303 and is subsequently heated by heating element 302 within the heating can. The degree to which the heating element 302 heats the water is controlled by the user control means 308 and is ultimately determined by a user of the shower unit selecting a required water output temperature. The heated P0963.spec -9water flows out of the device via a water outlet 306 and is dispensed, as required by a user, at a showerhead 309.

The water shut-off valve 304 may be positioned in the inlet 305, either before the flow controller 303, or immediately after the flow controller 303. The order in which the flow controller 303 and water valve 304 are positioned in the inlet to the heater can, can be varied as between different embodiments without departing from the invention.

Controller 308 comprises a water temperature selection control,'and a flow selection knob. The water temperature control varies the water temperature between hot and cold. The flow control knob turns the shower unit on and off, and increases a rate of water through the shower, thereby increasing or decreasing the rate of flow of water through the water valve and housing vessel. In the embodiments shown, by turning the controls either to full power, or to cold, the electrical power to the solenoid of water valve, 304 is turned on.

In other embodiments, power to the solenoid of water valve 304 can either be controlled by a rotary control switch or by an on/off switch. Therefore operation of the on/off power to the water control valve is either by rotary switch or by an on/off push button switch.

The shut-off valve when utilized in one mode of operation is configured to allow a flow of water through the water heater device, and when utilized in another mode of operation is operable to terminate the flow of water through the water heater device. The shut-off valve is supplied with electrical power via wiring 310 from controller 308. In the event of the loss of power to the shut-off valve 304 the valve is configured to switch between the first and second modes of operation following a finite time delay. The loss of power to the shut-off valve may be as a consequence of a user choosing to shut off the unit via control means 308 or the loss of power may result from a power cut such that mains electric power is lost to the shower unit and water heater device.

P0963.spec -10The shut-off valve terminates the flow of water through the device by blocking the passage of water through water inlet means 305.

When in a first mode of operation in which electric power is supplied to the water-shut off valve, the valve is open and allows a flow of water into the heating can. When in a third mode of operation in which electrical power is terminated to the water valve, after having immediately previously being supplied to the water valve, the water shut-off valve allows a flow of water through the heating chamber for a finite time period after the termination of power to the water shut off valve.

In a second mode of operation in which an electric power is supplied to the shut-off valve and a predetermined time period since electric power was last supplied, the shut-off valve is closed and terminates, the flow of water into the heater can.

The continued flow of water through the heater can containing the heating element immediately, following the loss of power to the water heater device, allows any remaining stored heat energy within the heating element to be transferred to the water flowing through the heater can such that this stored energy is dissipated.

Referring to Fig.4 herein there is illustrated schematically one example of a solenoid operated water shut-off valve according to a specific implementation of the present invention. The shut-off valve 400 comprises a solenoid actuator 401, and a valve body 402. Valve body 402 comprises a plastic or PTFE casing 403, having an inlet passage 404 for inlet of water; an outlet passage 405 for outlet of water; and a valve chamber 406 which is openable to allow the flow of water, when in an open position, and closable to block the flow of water when in a closed position. Valve chamber 406 comprises a tube portion 407 connected to the outlet, providing a seating 408. A closure member 409 moves towards and away from the seating. The closure member is mounted on a movable rubber P0963.spec -11diaphragm 410, which is molded into the casing 403. In an open position as shown in Fig. 4, the closure member is positioned away from the seating allowing flow of water from the inlet, through to the valve chamber and through the seating and through the outlet. In a closed position, the closure member blocks off the seating, preventing flow of water through the device. The closure member is controlled by the solenoid 401 and by the pressure of water in the chamber.

The solenoid comprises a plastics casing 411; a plurality of electric windings 412; a metallic plunger 413; a compression spring member 414; and a pair of electrical connectors 415. When electrical current is applied to the solenoid, the coils activate, causing the plunger to withdraw into the solenoid in a retracted position as shown. The force on the plunger provided by the magnetic field generated by the coil opposes the force provided by the spring, with a result that the force on the plunger exceeds the force on the spring and the plunger is able to retract into the solenoid.

When power is shut-off from the solenoid, there is no magnetic force to withdraw the plunger into the solenoid case, and the resilient compression spring urges the plunger member against the closure member, causing the closure member to close against the seating, thereby shutting off the flow of water through the device.

The closure member 409 whilst being triggered between the closed and opened positions by the solenoid, once triggered acts bi-stably between the open and closed positions due to water pressure on either side of the diaphragm 410.

Diaphragm 410 comprises a plurality of small apertures, through which water can flow. Water passing through the inlet 402 into an outer portion 416 of the chamber 406 passes through the small apertures into an inner antechamber 417 part of the chamber 406. Under conditions of no electric current to the solenoid, water passing through the inlet flows through the apertures and into the ante chamber 417, causing the ante chamber to pressurise and to urge the diaphragm towards the seating. Combined with the force provided by the spring member, on P0963.spec -12the plunger, this causes the closure member to close across the seating, thereby blocking the flow of water.

However, when the spring pressure on the closure member is removed, by electrical actuation of the solenoid, drawing the plunger back into the solenoid, water pressure in the outer chamber 416 acts on the diaphragm to urge the diaphragm and the closure member away from the seating, allowing passage of water to flow through the device.

Transition from the open to closed modes is initiated as soon as electrical power to the solenoid is terminated and is effected by virtue of water flowing from the inlet into the ante chamber, and combined with the force provided by the spring, urging the closure member across the seating, once the electric current is turned off. This process takes a finite amount of time, since it takes time for the water to flow through the apertures into the antechamber.

In the best mode, the time taken for the closure member to operate between the open and closed modes can be varied, such that after termination of electric current to the solenoid, a time delay in the period of 2 to 6 seconds can be designed, for the closure member to switch from the open to closed positions. In the best mode, a time delay period in the range 2 to 6 seconds is found optimal, however other time delays from removal of electric current from the solenoid to closure member and shut-off of the water flow can be designed.

A duration of the time delay can be modified by altering the relative rate of build up of pressure in the antechamber compared to the force provided by the spring member upon the plunger. The result is a water shut-off valve, which is solenoid activated, and which, on termination of power to the solenoid, has a mechanical time delay between moving from an open position, in which water is allowed to flow through the valve, to a closed position, in which the flow of water through the valve is closed off. The time delay in shutting down the water flow is not dependent upon continued electrical control to the solenoid, and once P0963.spec -13triggered, will operate mechanically under pressure of water, without the need for any electrical power.

Referring to Fig. 5 herein there is illustrated an overview of the operational modes of the water heater device according the specific implementation incorporating a shut-off valve. At stage 500 the shower unit and the water heater device, as described above, are operable such that the water valve is in the first mode of operation thereby allowing the flow of water through the device. Electrical power is terminated to the device at stage 501. This may be a result of a power cut to part of a building within which the device is installed or the termination of power to the water heater device via the use of a cord operated safety cut-off switch of the kind located in bath or shower rooms and the like, such safety switches being operable to terminate the power to any electrical items within the bath or shower room in-order to prevent risk of electrocution to a person.

There are three instances where electricity supply may be cut off to the solenoid. Firstly, by normal operation of the shower unit, for example by a user activating a rotary switch or a push button on/off switch. Secondly, by an external safety cut off switch being activated, external to the shower, and thirdly via a power cut to the electricity supply of a house or other building containing the shower, or by a miniature circuit breaker tripping, or a fuse blowing, cutting off the electric power to the shower unit as a whole.

The water valve enters its second mode of operation, and begins to close.

Water continues to flow through the shower unit in the event of the termination of power at stage 502 for a delay time period. As water continues to flow through the housing vessel and come into contact with the heating element heat energy stored in the heating element is dissipated at stage 503. The dissipation of this 0 stored heat energy at stage 503 substantially eliminates the problems identified with prior art water heaters as detailed in Fig.2.

P0963.spec -14Following this suitable time delay of, in the best mode according to the specific implementation approximately five seconds, water ceases to flow through the shower unit due to the blockage of the water inlet means at stage 504 by the closure of the water valve me the water valve enters its third mode of operation.

Referring to Fig. 6 there is illustrated a flow diagram detailing operational modes of the water heater device on Fig.3 At stage 600 the shower unit incorporating the water heater device is operational having a supply of electricity. According to a specific method of the present invention, the valve in the first mode of operation, is open at stage 501 thereby allowing the flow of water through the shower unit. The supply of electricity to the shower unit is then terminated at stage 502, the termination of electricity being a result of a power cut or the activation of a suitable safety cut off switch within a bath or shower room. Following the termination of electrical power to the shower unit in its second mode of operation, the water valve remains open or at least partially open, allowing the flow of water through the device and hence the dissipation of stored heat energy within the heating element at stage 603. At 604, a pressure imbalance exits on either side of the diaphragm and maintains the valve in an open or partially open position. Water continues to fiow through the water heater 0 device 605 and shower unit for a finite time period following the termination of power. The pressure on either side of the diaphragm is equalized at stage 606. The valve switches to the third mode of operation at stage 607 such that it terminates the flow of water flowing through the device. The result of the valve switching from its first mode to its third of operation, following a finite time delay, is the termination of the flow of water through the shower unit at 610, after a mechanically activated time delay.

Referring to Fig. 7 there is illustrated selected components of the water heater device according to the specific implementation of the present invention.

Fig. 7 illustrates the solenoid water valve 700 connected to a heater can 701. Connected to a first side of the solenoid diaphragm is water inlet means 702.

Water inlet 702 utilized in the specific implementation of the present invention is P0963.spec -15connected to a thermostatic mixer valve 703. The mixer valve 703 is operable to mix hot and cold water.

Water shut-off valve 700, when in a first mode of operation, allows the flow 5 of w'ater through water inlet means 702 and into the heater can 701.

The water heater device utilized within the specific implementation of the present invention is configurable for incorporation within a variety of electric shower units, including power showers, or in other hot water devices for use in washrooms or kitchens.

Claims (23)

Claims:

1. An electric water heater device, said device comprising: a water heater unit; a water shut-off valve for controlling a flow of water to said water heater unit; said water shut-off valve having a first mode of operation in which it allows a flow of water through said water heater unit, and a second mode of operation, in which it prevents flow of water to said water heater unit, said valve being configured to switch between said first mode of operation and said second mode of operation in response to a termination of electrical power; said water shut-off valve operable in use to provide a time delay between said first mode of operation and said second mode of operation, said time delay operating without the need for electrical power.

2. The water heater device as claimed in claim 1, which switches between said first and second modes of operation in response to a termination of power to said electric water heater device.

3. The water heater device as claimed in claim 1 or 2, wherein said predetermined time period is determined by a mechanical time delay inherent in the design of said water shut off valve.

4. The water heater device as claimed in any one of the preceding claims, wherein said predetermined time delay is activated by a pressure of water input into said water shut-off valve. P0963.spec -175. The water heater device as claimed in any one of the preceding claims, wherein said water heater unit comprises a water inlet for inlet of water to said water heater unit, wherein said water shut off valve controls a flow of water through said water inlet.

5. 6. The electric water heater device as claimed in any one of the preceding claims, and configured such that said time delay is in the range 2 or more seconds.

6. 7. The water heater device as claimed in any one of the preceding claims, wherein said time delay is configured to be in the range 2 to 6 seconds.

7. 8. The water heater device as claimed in any one of the preceding claims, wherein said shut-off valve comprises a solenoid controlled water valve.

8. 9. The water heater device as claimed in any one of the preceding claims, comprising an instantaneous electric water heater device for an instantaneous electric shower unit.

9. 10. A method of controlling a flow of water through an electric water heater device, said method comprising the steps of: supplying power to a shut-off valve being configured to control said flow of water through said device; channelling said flow of water through said shut-off valve, said shut-off valve being operable in a first mode of operation to allow said flow of water through said electric water heater device; in response to a termination of said power to said shut-off valve, said shutoff valve switching from said first mode of operation to a second mode of operation to terminate said flow of water through said device; P0963.spec -18wherein said shut-off valve is configured to switch from said first mode to said second mode following a finite time delay.

10. 11. .The method as claimed in claim 10, wherein said predetermined time period is determined by a mechanical time delay inherent in the design of said water shut off valve.

11. 12. The method as claimed in any one of claims 10 to 11, wherein said predetermined time delay is activated by a pressure of water input into said water shut-off valve.

12. 13. The method as claimed in any one of claims 10 to 12, further comprising: allowing said flow of water through said device for a finite time period following said termination of power to said flow controller.

13. 14. The method as claimed in any one of claims 10 to 13, wherein said termination of power to said shut-off valve is a result of a termination of power to said electric water heater device.

14. 15. The method as claimed in any one of claims 10 to 14, wherein said termination of power to said shut-off valve is a result of a user of said device selecting to terminate said power to said shut-off valve.

15. 16. The method as claimed in any one of claims 10 to 15, wherein said finite time delay is 2 seconds or more.

16. 17. The method as claimed in any one of claims 10 to 16, wherein said finite time delay is in the range 2 to 6 seconds. P0963.spec -1918. The method as claimed in any one of claims 10 to 17, wherein said shut-off valve comprises a diaphragm, said shut-off valve being configured to sense a first pressure on a first side of said diaphragm and on a second pressure on a second side of said diaphragm, and to close in response to a difference in said first and second pressures.

17. 19. The method as claimed in any one of claims 10 to 18, wherein said water valve comprises a solenoid.

18. 20. The method as claimed in any one of claims 10 to 19, wherein: said water shut-off valve is electronically activated, and operates to move from an open position, in which it allows flow of water, to a closed position, in which it prohibits flow of water, a predetermined time period after said electrical activation of the water shut off valve.

19. 21. The method as claimed in any one of claims 10 to 20, wherein: said shut-off valve is activated by an electric solenoid, wherein said shutoff valve operates in a first open mode of operation in which water is allowed to pass through said shut-off valve; and transfers to a second closed, mode of operation in which flow of water is prohibited through said shut-off valve, said transition from said first mode of operation to said second mode of operation occurring a predetermined time period after activation of said electric solenoid.

20. 22. A method of operating an electric shower unit capable of heating water, said shower unit comprising: a water heater device for heating a flow of water; and P0963.spec -20a water shut-off valve positioned to control input of water into said heating device; said method comprising: applying an electric signal to said water shut off valve, said electrical signal maintaining said water shut off valve in a first mode of operation, in which said shut off valve permits flow of water there through, and into said heater device; 10 on termination of said electrical signal to said water shut-off valve, said water shut-off valve operating in a third mode of operation, in which said valve waits a predetermined period of time, and during said predetermined period of time maintains an open position; and after said predetermined time period, said water vaive operates in a second mode of operation, in which said water valve 15 closes to shut off said supply of water to said heater device.

21. 23. The method as claimed in claim 22, wherein said predetermined time period is in the range 2 to 6 seconds. 2 0

22. 24. The method as claimed in claim 22 or 23, wherein said predetermined time period is determined by a mechanical time delay inherent in the design of said water shut off valve.

23. 25. The method as claimed in any one of claims 22 to 24, wherein said 25 predetermined time delay is activated by a pressure of water input into said water shut-off valve.