GB2331578A

GB2331578A - Water Heaters

Info

Publication number: GB2331578A
Application number: GB9824914A
Authority: GB
Inventors: Robin Edward Brash
Original assignee: Triton PLC
Current assignee: Triton PLC
Priority date: 1997-11-21
Filing date: 1998-11-16
Publication date: 1999-05-26
Anticipated expiration: 2018-11-16
Also published as: GB2356445B; GB0103223D0; GB9824914D0; GB2331578B; GB2356445A

Abstract

An electric instantaneous water heater comprises an electrically energised heater can 11, and an adjustable splitter valve 10 for feeding a proportion of a relatively cold water supply 5 fed to it to the heater can 11 to be heated therein. A mixing chamber 13 is provided for mixing the relatively hot water supplied by the heater can 11 with the remaining proportion of the cold water from the splitter valve 10 for affording a hot water output 19 at a required temperature. A reservoir chamber 18 fed from the mixing chamber 13 is preferably provided, and also a mains supply sensing arrangement whereby mains supply fluctuations may be equalised. Preferably, an on/off solenoid valve 6, a flow valve 7 and flow meter 9 are provided upstream from the splitter valve 10. These together with inlet temp, sensor 8 and mixed temp. sensor 17 are used in a control block 1 to control flow 3 and temperature 4. Preferably a reservoir 18 is provided downstream from the mixer to even out temp. variations as is a stabilised mains supply.

Description

2331578 1 Water Heaters This invention relates to water heaters and more

specifically to so- called instantaneous electric water heaters, especially for electric showers.

Existing instantaneous water heaters for electric showers comprise a heater can which includes one or more electric heater elements, the heater can being supplied with a flow of cold water which is heated in the heater can, the hot water being supplied to a shower head. The temperature of the water at the outlet of the heater can is dependent upon the rate of flow of water through it and the electrical power input to it. Such water hegers for showers are continually being developed and improved to cater for changing operating conditions and to provide improved performance and facilities.

It is an object of the present invention to provide an improved form of instantaneous water heater, especially suitable for an electric shower.

According to one aspect of the present invention there is provided an electric instantaneous water heater comprising an electrically energised heater can, an adjustable splitter valve for feeding a proportion of a relatively cold water supply fed to it to said heater can to be heated therein, means being provided for mixing the relatively hot water supplied by said heater can with the remaining proportion of the cold water from said splitter valve for affording a hot water output at a required temperature.

In a preferred water heater according to the first aspect of the invention, a flow control valve will be provided for controlling the relatively cold water supply fed to said splitter valve.

In carrying out the invention it may be arranged that said water heater comprises flow meter means for sensing the flow of said relatively cold water supply, temperature sensing means for sensing the temperature of said relatively cold water supply, further temperature sensing means for sensing the temperature of the hot water output from said mixing means, and control means operable in response to said temperature sensing means, said further temperature sensing 1 2 means and said flow meter means for controlling the energisation of said heater can and for controlling said splitter valve and said flow control valve.

Preferably, said control means comprises temperature setting means for selecting the temperature of said hot water output, and flow selection means for selecting the flow of said hot water output.

Advantageously, said water heater may comprise a solenoid valve for controlling said relatively cold water supply, said control means comprising switch means for effecting operation of said solenoid valve.

In one embodiment it may be arranged that said means for mixing comprises a mixing chamber, reservoir means being provided to which the output from said mixing chamber is fed.

Additionally it may be arranged that said control means comprises mains supply sensing means operable for controlling the energisation of said heater can and said flow control valve to minimise the effects of mains supply fluctuations.

According to a second aspect of the present invention there is provided an electric instantaneous water heater comprising an electrically energised heater can, means for feeding a relatively cold water supply to said heater can to be heated therein, means for mixing the relatively hot water supplied by said heater with a further supply of relatively cold water, and reservoir means to which the mixed output is fed for affording a hot water output.

In carrying out the invention according to said second aspect it may be arranged that said means for mixing comprises a mixing chamber the output from which is fed to said reservoir chamber.

According to a third aspect of the present invention there is provided an electric instantaneous water heater comprising an electrically energised heater can, means for feeding a relatively cold water supply to said heater can to be heated therein, and mains supply sensing means operable for controlling the energisation of said heater can andlor the flow of said relatively cold water supply for minimising the effects of mains supply fluctuations.

The electric instantaneous water heater in accordance with the first, 3 second and third aspects of the invention is especially applicable to an electric shower.

An exemplary embodiment of the invention will now be described, reference being made to the accompanying single figure drawing which is a diagrammatic block diagram of an electric instantaneous water heater in accordance with the present invention for use in a shower.

The electric instantaneous water heater shown in the drawing operates under the control of a control system 1 which comprises a start/stop push button 2, three flow rate push buttons 3 corresponding to high (H), medium (M) and low (L) flow rates and a temperature setting control 4.

The water heater comprises a cold water inlet 5 which feeds cold water to an onloff solenoid 6 which is controlled by the start/stop push button 2 under the control of the control system 1.

The output from the solenoid 6 is fed to a flow control valve 7 (which is typically motor driven) which is operated by the control system 1, and the temperature of the ambient water fed to the flow control valve 7 is sensed by a temperature sensor 8 the output from which is fed to the control system 1.

The output from the flow control valve 7 is fed to a flow meter 9 which measures the flow of water and affords an indication thereof to the control system 1, the output from flow meter 9 being fed to a splitter valve 10 (which is typically motor driven) which is adjustable under the control of the control system 1.

The splitter valve 10 acts as a proportioning valve and directs part of the flow of water input to it to a heater can 11 via a cold water feed 12, and directs the remaining part of the flow input to it to a mixing chamber 13 via a bypass feed 14. Thus, as the splitter valve 10 is adjusted, the flow of water to the heater can 11 increases and the flow of water to the mixer chamber 13 decreases or vice-versa.

The heater can 11 is of conventional form and contains a number, typically three, of heater elements the energisation of which is controlled by the 4 control system 1.

The heater can 11, when operating, heats the water fed to it, and hot water is output from it to the mixing chamber 13 via a hot water feed 15.

The hot water from the heater can 11 and the cold water from the bypass feed 14 are mixed in the mixing chamber 13.

The output 16 from the mixing chamber 13 is sensed by a temperature sensor 17 which affords an indication thereof to the control system 1, and is fed to a reservoir chamber 18 which feeds a hot water outlet 19 to which a shower head would normally be connected.

A typical operating sequence for the water heater thus far described is as follows:

A user selects the required temperature by means of the temperature setting control 4 and also sets the required water flow rate by means of the flow rate push buttons 3. The stop/start push button 2 is then operated and the control system 1 causes the solenoid 6 to be operated to feed cold water to the flow control valve 7.

The control system 1 then controls the operation of the flow control valve 7 and the energisation of the heater can 11, possibly in conjunction with the adjustable splitter valve 10, in order to deliver hot water at the required temperature and at the required flow rate to the hot water outlet 19.

Should a pressure change occur which causes a reduction in the flow of water to the cold water inlet 5, the following happens:

The reduction in flow is detected by the flow meter 9 and passed to the control system 1. An increase in temperature is detected by the temperature sensor 17. The control system 1 operates the splitter valve 10 to reduce the flow of cold water to the can 11 causing a reduction of the hot water from the can 11 and increases the flow of the cold water feed 14 to the mixing chamber 13 in order to maintain the required outlet temperature. The control system 1 then simultaneously adjusts the flow control valve 7 and the power to the heater can 1 11 to restore the flow whilst maintaining the temperature.

On restoration of water pressure which causes an increase in flow, the following happens:

The increase in flow is detected by the flow meter 9 and passed to the control system 1. A decrease in temperature is detected by the temperature sensor 17. The control system 1 operates the splitter valve 10 to increase the flow of cold water to the can 11 causing an increase of the hot water from the can 11 and decreases the flow of the cold water feed 12 to the mixing chamber 13 in order to maintain the required temperature. The control system 1 then simultaneously adjusts the flow control valve 7 and the power to the heater can 11 to restore the flow whilst maintaining the temperature.

Any peaks of temperature which may occur at the output 16 of the mixing chamber 13 are reduced due to the affect of the reservoir chamber 18 which contains water at a steady state temperature. For example, if the reservoir chamber 18 contains water at say 40 'C and a peak of 42 C of water is fed to the reservoir chamber 18 from the mixing chamber 13, the water temperature at outlet 19 would be less than 42C due to the cooling effect of the reservoir chamber 18. If the reservoir chamber 18 contains water at say 4VC and a peak of WC water is fed to the reservoir chamber 18 from the mixing chamber 13, the water temperature at outlet 19 would be more than 3WC but less than 4WC due to the heating effect of the reservoir chamber 18.

It has been found that in some areas of the country the operation of instantaneous water heaters in the form of electric showers can be affected by changes in mains supply voltage, and in the control system 1 which has been described the mains supply voltage is monitored and the flow control valve 7, the energisation of the heater can 11 and, if necessary the adjustable splitter valve 10, are operated in order to compensate for any mains supply fluctuations. For monitoring purposes, the mains supply may be half-wave rectified, filtered and then subjected to analogue-to-digital conversion to afford a d.c. signal indicative of the amplitude of the mains supply signal.

The electric instantaneous water heater which has been described is ideally 6 suited for shower applications, but may have more general application, e. g. in providing hot water to a hand basin, etc.

The electric instantaneous water heater which has been described has been given by way of example only, and although the features of providing the splitter valve 10, the reservoir chamber 18 and the mains supply monitoring and control have all been incorporated, it should be appreciated that each of these features is individually believed to be novel and may be used independently of each other.

7

Claims

1. An electric instantaneous water heater comprising an electrically energised heater can, an adjustable splitter valve for feeding a proportion of a relatively cold water supply fed to it to said heater can to be heated therein, means being provided for mixing the relatively hot water supplied by said heater can with the remaining proportion of the cold water from said splitter valve for affording a hot water output at a required temperature.

2. A water heater as claimed in claim 1, comprising a flow control valve for controlling the relatively cold water supply fed to said splitter valve.

3. A water heater as claimed in claim 2, comprising flow meter means for sensing the flow of said relatively cold water supply, temperature sensing means for sensing the temperature of said relatively cold water supply, further temperature sensing means for sensing the temperature of the hot water output from said mixing means, and control means operable in response to said temperature sensing means, said further temperature sensing means and said flow meter means for controlling the energisation of said heater can and for controlling said splitter valve and said flow control valve.

4. A water heater as claimed in claim 3, in which said control means comprises temperature setting means for selecting the temperature of said hot water output, and flow selection means for selecting the flow of said hot water output.

5. A water heater as claimed in claim 4, comprising a solenoid valve for controlling said relatively cold water supply, said control means comprising switch means for effecting operation of said solenoid valve.

6. A water heater as claimed in any preceding claim, in which said means for mixing comprises a mixing chamber, and in which reservoir means is provided to which the output from said mixing chamber is fed.

7. A water heater as claimed in any of claims 4 to 6, in which said control means comprises mains supply sensing means operable for controlling the 8 energisation of said heater can and said flow control valve to minimise the effects of mains supply fluctuations.

8. An electric instantaneous water heater comprising an electrically energised heater can, means for feeding a relatively cold water supply to said heater to be heated therein, means for mixing the relatively hot water supplied by said heater with a further supply of relatively cold water, and reservoir means to which the mixed output is fed for affording a hot water output.

9. A water heater as claimed in claim 8, in which said means for mixing comprises a mixing chamber the output from which is fed to said reservoir chamber.

10. An electric instantaneous water heater comprising an electrically energised heater can, means for feeding a relatively cold water supply to said heater can to be heated therein, and mains supply sensing means operable for controlling the energisation of said heater can andlor the flow of said relatively cold water supply for minimising the effects of mains supply fluctuations.

11. An electric instantaneous water heater substantially as hereinbefore described with reference to the accompanying drawing.

12. An electric instantaneous water heater as claimed in any preceding claim in the form or an electric shower.