GB2356445A

GB2356445A - Instantaneous water heater

Info

Publication number: GB2356445A
Application number: GB0103223A
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: 2001-05-23
Anticipated expiration: 2018-11-16
Also published as: GB2356445B; GB0103223D0; GB2331578B; GB9824914D0; GB2331578A

Abstract

An electric instantaneous water heater comprises: an electrically energised heater can 11; means 12 for feeding a proportion of a relatively cold water supply to said heater to be heated therein; means 13 for mixing a relatively hot water supply by said heater can with the remaining proportion of said cold water supply; and a reservoir chamber 18 to which the mixed water output is fed for affording a hot water output. Advantageously, the means for mixing may comprise a mixing chamber the output of which is fed to the reservoir chamber. Preferably, the heater has a splitter valve 10, flow control valve 7 and a control 1 operating the flow control, splitter and heater can as a function of inlet, outlet and flow values. Preferably, the heater operates as a shower.

Description

2356445 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 lo the heater can is dependent upon the rate of flow of water through it and the electrical power input to it. Such water heaters 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.

In accordance with the present invention there is provided an electric instantaneous water heater compdsing: an electrically energised heater can; means for feeding a proportion of a relatively cold water supply to said heater to be heated therein; means for mixing the relatively hot water supplied by said heater can with the remaining proportion of said cold water supply; and a reservoir chamber to which the mixed water output is fed for affording a hot water output.

In accordance with preferred embodiments of the present invention there may be 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 P0689.spec can with the remaining proportion of the cold water from said splitter valve for affording a hot water output at a room temperature.

In a preferred water heater according to the invention, a flow control valve is 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 compHses 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 the mixing means and control means operable in response to said temperature means, said further temperature sensing means and said flow meter means being configured 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. In accordance with the invention, reservoir means are 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 fluctuation.

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

Yet further embodiments of the present invention may provide 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, a mains supply sensing means operable for controlling the energisation of said heater can and/or the flow of said relatively cold water supply for minimizing the effects of mains supply fluctuations.

is The electric instantaneous water heater in accordance with 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 on/off 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 5 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 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 lo 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 viceversa.

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 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 heaters thus far described is as 5 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 is adjustable splitter valve space 10, in order to deliver hot water at the required temperature and tat 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 tot he 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 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 splifter valve 10 to increase the 5 flow of cold water to the can 11 causing an increase of the hot water from the can 11 and decreases the flow of 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 400C and a peak of 420C of water is fed to the reservoir chamber 18 from the mixing chamber 13, the water temperature at outlet 19 would be less than 420C due to the cooling effect of the reservoir chamber 18. If the reservoir chamber 18 contains water at say 400C and a peak of 380C water is fed to the reservoir chamber 18 from the mixing chamber 13, the water temperature at outlet 19 would be more than 380C but less than 400C 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 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 splifter 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 lo features is individually believed to be novel and may be used independently of each other.

Claims

1. An electric instantaneous water heater comprising:

an electrically energised heater can; means for feeding a proportion of a relatively cold water supply to said heater to be heated therein; means for mixing the relatively hot water supplied by said heater can with the remaining proportion of said cold water supply; and a reservoir chamber to which the mixed water output is fed for affording a hot water output.

2. A water heater as claimed in claim 1, in which said means for mixing comprises a mixing chamber the output from which is fed to said reservoir chamber.

3. A water heater as claimed in claim 1 or claim 2, wherein said reservoir chamber is configured to effect cooling of said input mixed water if said input mixed water is at a higher temperature than the water in the said chamber.

4. A water heater as claimed in claim 1 or claim 2, wherein said 2s reservoir chamber in configured to effect a heating effect upon said input mixed water if said input mixed water is at a lower temperature than the water in said chamber.

5. A water heater as claimed in any of the above claims, wherein said reservoir chamber feeds a hot water outlet to which a domestic shower head is connected.

6. A water heater as claimed in any of the above claims, wherein said means for proportioning said cold water supply comprises a splifter valve capable of reducing or increasing the flow of water from said heater can.

7. A water heater as claimed in claim 6, wherein said splifter valve is controlled by an electronic control system configured to simultaneously adjust a flow control valve and the power to said heater can.

8. A water heater as claimed in claim 7, wherein said flow control valve is located upstream of said splitter valve.

9. A water heater as claimed in claim 7 or claim 8, wherein said flow control valve is monitored by a flow meter which measures the flow of water and affords an indication thereof to said control system.

10. A water heater as claimed in any of claims 7, 8 or 9, wherein said flow control valve is sensed by a temperature sensor.

11. A water heater as claimed in any of claims 7 - 10, wherein said control means comprises mains supply sensing means operable for controlling energisation of said heater can to minimise the effects of mains supply fluctuation.

12. A water heater as claimed in claim 11, wherein said mains supply sensing means additionally controls the energisation of a flow control valve to minimise the effects of mains supply fluctuations.

13. A water heater as claimed in any of claims 7 - 12, wherein said control means is operable in response to a first and a second temperature sensing means, said first temperature sensing means being located upstream of said splifter valve and said second sensing means being located to detect the temperature of said mixed water.

14. An electric instantaneous water heater substantially as herein 5 before described with reference to the accompanying drawing.

15. An electric instantaneous water heater as claimed in any proceeding claim in the form of an electric shower.