GB2482916A

GB2482916A - Water heater that determines if power is being supplied to an electric heating element

Info

Publication number: GB2482916A
Application number: GB1013983.0A
Authority: GB
Inventors: William Gardiner; Richard Horne
Original assignee: Triton PLC
Current assignee: Triton PLC
Priority date: 2010-08-20
Filing date: 2010-08-20
Publication date: 2012-02-22
Anticipated expiration: 2030-08-20
Also published as: GB2482916B; GB201013983D0; IE86776B1; IE20110368A1

Abstract

A water heater has an electrically operated valve 14 for controlling water flow through the heater; a heating chamber 16 with an electrical heating element; a user operable switch (20, fig 1) for turning the heater on/off; and a controller 23,24 controlling electrical power to the element, with means (e.g. a voltmeter or ammeter) for measuring or determining whether power is being supplied to the heating element. If a power relay becomes stuck in the on condition when the user initiates shutdown, the controller can prevent the valve from closing or repeatedly reopen the valve. A visual or audible warning can be given of the fault. The heater may supply a showerhead.

Description

Title: A Water Heater and a Method of Controlling a Water Heater

Description of Invention

This invention relates to a water heater and a method of controlling a water heater. The invention has been devised primarily in relation to water heaters for use in showers, but it will be apparent to those skilled in the art, and it should be understood, that the invention may be utilised in many other types of devices.

In order to provide heated water for private and industrial sanitary purposes, it is known to use an electric instantaneous water heater device which intakes cool water and outputs heated water. Water enters the water heater device, is heated by at least one heating element, and exits the water heating device via an outlet. Electric water heating devices for electrically operated showers comprise a housing containing the water heater. The shower includes an inlet which is connected either to a mains water supply or to a pump which pumps water through the inlet, an outlet to a showerhead and a chamber therebetween containing at least one electric heating element. Water passing though the chamber is heated by the electric heating element. The shower includes a user-operable knob(s) or button(s) for selecting or adjusting the temperature of the water exiting through the outlet.

Electric showers incorporating such a water heater have at least one controller for controlling the electrical power supply to the heating element. The controller can take many forms, e.g. an electrical relay switch or a semi-conductor. When activated, the relay permits electricity to flow to the heating element, and when deactivated, the relay prevents electricity flowing to the heating element. When a user decides to turn the shower off, using a suitable button or switch on a housing of the shower, an electrically controlled shut down process firstly deactivates the relay, so as to turn off the heating element and then, after a predetermined time period (or when the water outlet temperature has reduced to a predetermined value), closes a solenoid valve which is positioned at or near the water inlet. The order of this controlled shutdown is provided so as to ensure that a majority of the heated water inside the heating chamber is purged from the shower, before the water inlet is closed. This is aimed at preventing excessively heated water exiting the shower the next time the shower is operated (which may occur if the solenoid is closed at the same time as the heating element is turned off, as the water in the chamber would continue to be heated even as the heating element cooled).

The applicant has found that in the case of a relay switch, which controls the supply of electricity to the heating element, the relay can, rarely, become stuck in an on' or closed' condition (i.e. a position which permits the flow of electric current therethrough) due to the contacts in the relay welding' to each other as a result of current flowing therethrough. Thus, after the user has turned off the shower, electricity may still flow to the heating element, through the relay switch, thus causing the water heater to continue to heat the water in its chamber even after the inlet to the shower has been closed. Other component failures within the shower can also result in the heater being maintained on', which can lead to the same or similar issues. There are some known secondary protection mechanisms, e.g. thermal cut out devices, but these often do not act quickly enough.

According to a first aspect of the invention, we provide a water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user operable switch for turning the water heater on/off; and an electrically operated controller for controlling electrical power supply to the heating element, wherein the water heater includes means for determining whether power is being supplied to the heating element.

According to a second aspect of the invention, we provide a method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes determining whether power is being supplied to the heating element and if any power is being supplied to the heating element, preventing the electrically operated valve from closing so as to permit water to continue to flow into the water heater.

According to a third aspect of the invention, we provide a method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes, in response to a user operating the switch so as to turn the water heater off, the steps of:-operating the electrically operated controller so as to attempt to disconnect the electrical power supply to the heating element; determining whether power is being supplied to the heating element; and if any power is being supplied to the heating element, preventing the electrically operated valve from closing so as to permit water to continue to flow into the water heater.

According to a fourth aspect of the invention, we provide a method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes, in response to a user operating the switch so as to turn the water heater off, the steps of:-operating the electrically operated controller so as to attempt to disconnect the electrical power supply to the heating element; closing the electrically operated valve after a predetermined period of time; determining whether power is being supplied to the heating element; and if any power is being supplied to the heating element, opening the electrically operated valve so as to permit water to flow into the water heater.

Further features of the first, second, third and fourth aspects of the invention are set forth in the dependent claims appended hereto.

Embodiments of the invention will be described by way of example only, with reference to the accompanying drawings, of which:-Figure 1 is a front view of a shower including a water heater in accordance with the present invention; and Figure 2 is a front view of the internals working components of the shower of figure 1.

Referring to the figures, there is shown a shower 10 in accordance with the present invention. The shower 10 includes a water heater for elevating the temperature of incoming water so that it can be of use for showering. The shower includes an inlet 12 to receive water, which may be connected directly to a cold water mains supply pipe or to another source of relatively cold water, e.g. a header tank possibly in combination with a pump. Flow of water through the inlet 12 is controlled by an electrically operated valve 14, which is in this example a solenoid valve.

Fluidly connected to the inlet 12, via a conduit 15, is a heating chamber 16 which receives water from the inlet 12. The heating chamber 16 in this example includes a pair of electrically operated heating elements (not shown) which are configured to raise the temperature of the water flowing in the chamber 16 such that the water exits at the desired temperature for a user of the shower 10. The heating elements are configured either to work together or alone, in order to achieve different levels of heating capability. The shower 10 includes means for permitting the user to select the desired temperature of the water, using the rotatable knob 18 (buttons could be used instead). The shower 10 in the current example is a thermostatic shower, which is configured hold the outlet water temperature substantially at a selected level.

In order to achieve this, a thermostatic valve 13 is provided (see figure 2), which is adjustable by manual rotation of the knob 18. The shower includes a display 17 which displays the current temperature of water exiting from the shower 10.

In an alternative embodiment, where the shower does not have a thermostatic valve, the shower may include a control (e.g. a knob(s) or button(s)) to permit the user to select which heating element is being powered. In one example, the control may have three settings; in setting 1) only the first heating element is used to heat the incoming water; in setting 2) only the second heating element is used to heat the incoming water; and in setting 3) both heating elements are used to heat the incoming water.

The shower 10 also includes an outlet 30 from the valve 13 through which heated water exits to a showerhead (not shown) so that it can be used by the user. The shower 10 also includes a user operable switch 20 for turning the water heater on/off. The switch 20 also acts to open the valve 14 to permit water to flow through the inlet 12. It should be appreciated that in an alternative embodiment the electrically operated valve 14 could be provided at or near the outlet from the shower 10, instead of at the inlet 12.

The heating chamber 16 includes a pressure relief valve 22 which acts as a vent from the heating chamber 16 if the pressure inside the chamber 16 exceeds a predetermined value. In other words, the valve 22 acts as a safety feature. Another safety feature of the shower 10 is that is includes a pressure switch 21, which, via the tube 25 connected to the solenoid valve 14, senses whether the pressure of the incoming water is high enough for the shower 10 (particularly the heating elements) to operate safely. If the incoming water pressure is too low, the pressure switch 21 will operate and cut off electrical power supply to the heating chamber 16, and thus the heating elements.

The shower 10 also includes a pair of electrically operated controllers 23, 24 for controlling electrical power supply to the heating elements. In this example, each electrically operated controller 23, 24 is configured to control electrical power supply to a respective heating element within the heating chamber 16, although it should be appreciated that both heating elements could, if desired, be controlled by a single electrically operated controller. In this example each electrically operated controller 23, 24 is a relay switch.

Each relay switch 23, 24 has two states of operation -either on' or off'. In the off' condition, the relay switch is open such that electricity is prevented from flowing to the heating element. In the on' condition, the relay switch is closed which completes a circuit thus permitting electricity to flow to the heating element. The relay switches 23, 24 therefore act as switches between the mains electricity supply, which is connected to the shower at 26, and the heating elements in the chamber 16 In the present invention, the shower 10 includes means for determining whether power is being supplied to each heating element, and this is achieved, in the present example, by a measuring device (not shown) which measures whether there is a voltage across the heating elements. A suitable device is known as a voltmeter, which measures the electrical potential between two points in an electrical circuit. In the present example there are two such measuring devices, one for measuring the voltage across each heating element. However, there could be only one measuring device for measuring the voltage across both heating elements.

In an alternative embodiment, the means for determining whether power is being supplied to the heating elements may include a device for measuring whether current is flowing through each relay switch 23, 24. The measuring device may be an ammeter. The shower may have a single ammeter which measures current across both switches 23, 24 or two ammeters, one for each switch 23, 24. In this alternative embodiment, if it is determined that electricity is flowing through each relay switch 23, 24, then it follows that electricity is also flowing to the respective heating element and thus the respective heating element is heating the water in the chamber 16. If it is determined that electricity is not flowing through the relay switch 23, 24, then it follows that electricity is not flowing to the respective heating element and thus the respective heating element is not heating the water in the chamber 16.

In accordance with the present invention, the shower 10 is configured to offer improved safety due to its component parts and their method of operation.

When a user decides to turn the shower 10 off, he/she presses the button 20.

This starts an electrically controlled shut down program/sequence which firstly attempts to deactivate the relays 23, 24, 50 as to disconnect the electrical power supply to the heating elements. The shutdown program then, via the voltmeter(s), determines whether power is still being supplied to the heating elements. If it is determined that electricity is still being supplied to the heating elements (i.e. if the voltage measured across both heating elements collectively, or either of the heating elements individually, is greater than zero), this may be because one or both relays 23, 24 have welded in an on' condition. The shutdown program/sequence in accordance with the present invention will advantageously prevent the electrically operated valve 14 from closing the inlet 12 (which would otherwise have been the next shutdown step) so as to permit water to continue to flow through the inlet 12 and into the heating chamber 16. This improved phased shutdown therefore prevents standing' water in the heating chamber 16 being further heated whilst the valve 14 is closed, and therefore prevents the issues associated with this.

The shower 10 may be configured to repeat the shutdown program after a predetermined time, for example after a fraction of a second or a number of seconds. If during this repeated shutdown program one or both relay switches 23, 24 still do not turn off' (e.g. they remain welded'), the system will indicate to the user, e.g. on the display 17, via a light (e.g. an LED) visible at the front face of the shower 10 or via an audible warning that the shower is not correctly shutting down. The shower 10 may be configured to repeat the shutdown program a plurality of times.

If, on the other hand, during the repeated shutdown program the voltage measured across the heating elements is zero, the next stage of the shutdown program will be the closing of the electrically operated valve 14 so as to close the inlet 12. There will, preferably, be a time delay before the valve 14 is closed so as to purge already heated water from the chamber 16.

If the shower continues to permit water to flow therethrough, because the voltage measured across the heating elements is not zero, even after the user has pressed the off button 20 a number of times, the user will likely turn off the shower at the mains isolating' switch. The user should then contact an appropriately qualified person to service, repair and/or replace the shower 10.

In an alternative shutdown program, when a user decides to turn the shower off, by pressing the button 20, the first step of the program is that an attempt is made to deactivate the relays 23, 24, so as to turn off the heating elements. The shutdown program then, after a predetermined time period, closes the valve 14. The time delay is provided so as to purge already heated water from inside the chamber 16. The shutdown program then, via the voltmeter(s), measures whether power is being supplied to the heating elements. If it is determined that power is being supplied to the heating elements this may, again, be because one or both relays 23, 24 have welded in an on' condition. If this occurs, the shutdown process will re-open the valve 14 so as to permit water to again start flowing through the inlet 12 and into the heating chamber 16. This alternative phased shutdown also prevents standing' water in the heating chamber 16 being further heated whilst the inlet 12 is closed, and therefore prevents the issues associated with this.

The shower 10 may be configured to repeat this alternative shutdown program after a predetermined time. If during this repeated shutdown program, after the valve 14 is closed, one or both relay switches 23, 24 still do not turn off' (i.e. they remain welded'), the system will reopen the valve 14 and indicate to the user, e.g. on the display 17, via a light (e.g. an LED) visible at the front face of the shower 10 or via an audible warning that the shower is not correctly shutting down. The shower 10 may be configured to repeat the shutdown program a plurality of times before indicating to the user that shower is not correctly shutting down.

If, on the other hand, during the repeated shutdown program zero voltage is measured across the heating elements, the valve 14 will remain closed and thus the shower will remain off'.

If the shower continues to permit water to flow therethrough, intermittently as a result of the valve 14 being closed and then re-opened, even after the user has pressed the off button 20 a number of times, the user will likely turn off the shower at the mains isolating' switch.

Although the method of operation of the shower can be used during the shutdown program/sequence of the shower, it can advantageously be used throughout operation of the shower by constantly monitoring whether power is being supplied to the heating elements and maintaining the valve 14 open in all conditions until no power is being supplied to the heating elements. Thus, the voltmeter may be configured to constantly, or at least a predetermined intervals during operation of the shower, measure the voltage across the heating elements, and only if the voltmeter value is zero will the valve 14 be permitted to close.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS1. A water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user operable switch for turning the water heater on/off; and an electrically operated controller for controlling electrical power supply to the heating element, wherein the water heater includes means for determining whether power is being supplied to the heating element.
2. A water heater according to claim 1 wherein the water heater includes means for preventing the electrically operated valve from closing if power is being supplied to the heating element.
3. A water heater according to any preceding claim including audio and/or visual indicating means for indicating whether electricity is being supplied to the heating element.
4. A water heater according to any preceding claim including audio and/or visual indicating means for indicating when power is not being supplied to the heating element.
5. A water heater according to claim 4 wherein the audio and/or visual indicating means is configured to indicate whether power is being supplied to the heating element after a user has activated the user operable switch so as to turn the water heater off.
6. A water heater according to any preceding claim wherein the means for determining whether power is being supplied to the heating element measures a voltage across the heating element.
7. A water heater according to any one of claims 1 to 6 wherein the means for determining whether power is being supplied to the heating element measures whether current is flowing through the controller.
8. A water heater according to any preceding claim wherein the water heater includes two heating elements, each heating element being controlled by a respective electrically operated controller, and wherein the water heater includes means for determining whether power is being supplied to both heating elements.
9. A water heater according to any one of claims 1 to 7 wherein the water heater includes two heating elements, each heating element being controlled by a respective electrically operated controller, and wherein the water heater includes respective means for determining whether power is being supplied to each heating element.
10. A water heater according to any one of claims 1 to 7 wherein the water heater includes two heating elements, both heating elements being controlled by a single electrically operated controller.
11. A water heater according to any preceding claim where in the electrically operated controller is a relay switch or a semi-conductor.
12. A water heater according to any preceding claims for incorporation into a shower.
13. A shower including a water heater according to any one of the preceding claims.
14. A method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes determining whether power is being supplied to the heating element and if any power is being supplied to the heating element, preventing the electrically operated valve from closing so as to permit water to continue to flow into the water heater.
15. A method according to claim 14 which is performed at predetermined time periods during operation of the water heater.
16. A method according to claim 14 which is performed continuously during operation of the water heater.
17. A method according to claim 14 which is performed in response to a user operating the switch so as to turn the water heater off.
18. A method according to any one of claims 14 to 17 wherein the step of determining whether power is being supplied to the heating element includes measuring a voltage across the heating element.
19. A method according to any one of claims 14 to 17 wherein the step of determining whether power is being supplied to the heating element includes measuring current flowing through the controller.
20. A method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes, in response to a user operating the switch so as to turn the water heater off, the steps of:-operating the electrically operated controller so as to attempt to disconnect the electrical power supply to the heating element; determining whether power is being supplied to the heating element; and if any power is being supplied to the heating element, preventing the electrically operated valve from closing so as to permit water to continue to flow into the water heater.
21. A method according to claim 20 which includes the further steps of, after a predetermined further period of time, determining whether electricity is being supplied to the heating element, and, if any electricity is being supplied to the heating element, preventing the electrically operated valve from closing so as to permit water to continue to flow into the water heater.
22. A method according to claim 20 or claim 21 which includes the further step of determining whether electricity is being supplied to the heating element, and, if no electricity is being supplied to the heating element operating closing the electrically operated valve.
23. A method of controlling the operation of a water heater, the water heater having:-an inlet to receive water; an electrically operated valve for controlling flow of water through the water heater; a heating chamber fluidly connected to the inlet to receive water, the heating chamber including an electrically operated heating element for heating the received water; an outlet from the chamber for heated water; a user actuatable switch for turning the water heater on/off; an electrically operated controller for controlling electrical power supply to the heating element; and means for determining whether power is being supplied to the heating element, wherein the method includes, in response to a user operating the switch so as to turn the water heater off, the steps of:-operating the electrically operated controller so as to attempt to disconnect the electrical power supply to the heating element; closing the electrically operated valve after a predetermined period of time; determining whether power is being supplied to the heating element; and if any power is being supplied to the heating element, opening the electrically operated valve so as to permit water to flow into the water heater.
24. A method according to claim 23 which includes the further steps of, after a predetermined further period of time, closing the electrically operated valve, determining whether power is being supplied to the heating element, and, if power is being supplied to the heating element, opening the electrically operated valve so as to permit water to flow into the water heater.
25. A method according to claim 23 or claim 23 which includes the further step of determining whether power is being supplied to the heating element, and, if no power is being supplied to the heating element maintaining closed the electrically operated valve.
26. A method according to any one of claims 20 to 25 wherein the step of determining whether power is being supplied to the heating element includes measuring a voltage across the heating element.
27. A method according to any one of claims 20 to 25 wherein the step of determining whether power is being supplied to the heating element includes measuring current flowing through the controller.
28. A water heater substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
29. A method of controlling the operation of a water heater substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
30. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.