GB2187828A - Water heater control valve - Google Patents

Abstract

A water heater control valve particularly for an instantaneous shower heater, having a monoblock valve body (10) which, in addition to a water inlet (14) and water outlet (16), incorporates a solenoid valve (18) serving as an on/off tap, a flow control and stabilisation valve (20) and a pressure switch (24) controlling heat exchange elements 30. A mounting flange (32) allows direct mounting of a heat exchanger 12 to the valve body. <IMAGE>

Description

SPECIFICATION Water heater control valve Field of the Invention This invention concerns water heater control valves, particularly control valves suitable for use in instantaneous water heaters, for example with showers.

Background of the invention In an instantaneous water heater, water is heated as it flows over a set of heated elements in a heat exchanger. The temperature rise of the water is proportional to the flow rate. Thus the outlet temperature, for a given energy input, is the sum of the ambient inlet water temperature and the temperature rise.

Controls for such a water heater must enable control of the following three functions: 1. Stopping of water flow when the heater is not in use.

2. Adjustment of water flow rate and hence of outlet temperature.

3. Energising of heater elements only when water is flowing.

Hitherto these three functions have been carried out by three discrete components connected together by conventional means, such as by interlinking pipework. Thus a typical conventional instantaneous electric water heater comprises the following components: a) A solenoid valve which acts as an electrical on/off inlet water tap.

b) A flow control and stabilising valve which controls the flow of water through the heater and detects and compensates for variations in inlet water pressure thus ensuring a constant rate of flow at a given setting.

c) A pressure switch which acts to ensure that power is applied to the heater elements only when water is flowing through the heater at greater than a pre-set minimum rate.

d) A heat exchanger.

The above components (together with others) are individually assembled into and secured within the back plate of the heater outer casing, linked by connecting pipes.

The invention.

According to the present invention there is provided a water heater control valve comprising a monoblock valve body with a water inlet and a water outlet and incorporating the following components: 1. an on/off water flow control valve; 2. a flow control valve for controlling the rate of water flow; and 3. a switch for controlling an associate water heater.

Most preferably, the monoblock valve body also incorporates a mounting flange for the heat exchanger.

By incorporating several components into a monoblock valve body benefits may be achieved in terms of reduced overall size, improved reliability and reduced cost as compared with conventional arrangements.

The water flow control valve conveniently comprises a solenoid or manually operable valve which acts as an electrical on/off inlet water tap.

The flow control valve preferably also acts as a stabilising valve, which detects and compensates for variations in inlet water pressure thus ensuring a constant rate of flow and hence constant outlet temperature at a given setting. A volume governor is generally preferred to a pressure regulator, i.e. with the control flow stabilised rather than pressure stabilised, although for cost reasons it may be preferred to use a pressure stabilised valve.

Indicator means are conveniently associated with the valve, e.g. with a valve spindle, to indicate the valve position.

The switch preferably acts to energise the heater only when water flow exceeds a predetermined minimum level. The switch is conveniently a switch assembly which senses pressure resulting from the flow of water through a restrictor situated between the low pressure side of the valve assembly and the heat exchanger. The switch conveniently acts to operate two microswitches for controlling operation of, e.g., electric heater elements of a heat exchanger.

The valve body preferably also includes a connector with water inlet and outlet for connection to a heat exchanger, conveniently electrically operated.

In a preferred arrangement cold water entering via the inlet flows through the on/off valve and the flow control valve and passes via the connector to a heat exchanger. Water heated in the heat exchanger is returned to the valve body via the connector and passes to the outlet.

Brief description of drawings.

An embodiment of water heater control valve in accordance with the invention for use with shower instantaneous electric water heaters will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic view diagrammatically illustrating the general arrangement of an embodiment of monoblock valve in accordance with the present invention with associated heater exchanger; Figure 2 is a front view of a practical embodiment of the monoblock valve in accordance with the present invention; Figure 3 is a bottom view of the monoblock valve of Fig. 2; and Figure 4 is a side view of the monoblock valve of Figs. 2 and 3 with associated heat exchange tank.

Detailed description of embodiment Fig. 1 illustrates an instantaneous electric water heater for a shower comprising a one piece or monoblock valve body 10 and heat exchanger 12. Monoblock valve body 10 has a cold water inlet 14, typically in the form of a 15mm diameter tube or a 15mm female compression fitting, and a hot water outlet 16 in the form of a threaded 1/2" BSP fitting.

Valve body 10 further incorporates a solenoid valve section 18, a flow control and stabilising valve 20, with flow control spindle 22, a pressure switch assembly section 24 with mountings for two V3 series microswitches 25, and a flange 32 for the direct mounting of the heat exchanger 12 to the monoblock valve body.

The heat exchanger 12 comprises a copper or plastics tube 26 with a copper standpipe 28 extending therethrough and with electrically powered heater elements 30. Said heat exchanger 12 is sealingly secured to the valve body 10 via the mounting flange 32, with provision being made for cold water to flow from valve body 10 to heater exchanger 12 for heating and for heated water to be returned to valve body 10.

The illustrated arrangement forms part of a shower unit, being mounted in a housing (not shown); with inlet 14 connected to a supply of cold water and outlet 16 connected to a hose (not shown) leading to a shower head or handset.

In use when water heating is required solenoid valve section 18 is activated, typically being electrically operated from a 240V a.c.

mains supply although various other voltages normally up to 240V may be used, to open the valve. When the valve is closed it acts to stop water flow against water pressures of 0.3 bar to 10 bar. Opening of the valve permits flow of cold water into valve body 10 via inlet 14 and firstly through the solenoid valve section 18. Cold water then passes through the flow control and stabilising valve 20, which is a pressure stabilised valve which acts to control the flow of water through the arrangement and detects and compensates for variations in inlet water pressure, thus ensuring a constant rate of flow at a given setting.

With water inlet pressure between 1 bar and 10 bar and e.g. a 1.25 meter hose and handset fitted to the outlet, it is possible to adjust the flow rate between 1.75 1/min. and 7.00 1/min. The outlet pressure at 7.00 1/min is at least 0.5 bar. When the inlet pressure is between 1 bar and 10 bar the flow rate does not change by more than 5% after a change of 2 bar, providing the final pressure remains within the above limits.

Indicator means (not shown) are associated with the valve spindle 22 for indicating the position of the valve.

Cold water then flows from the valve body 10 to heat exchanger 12 to be heated, with heated water then being returned to valve body 10 to be passed to outlet 16.

The pressure switch assembly section 24 controls the heat exchanger heater elements and acts to switch the heater elements on when water flows through the switch at greater than a preset minimum rate. The switch is designed to switch on at a flow of 2.2 1/min and to switch off at a flow of 2.0 1/min. Thus if water flow is too low the heater elements are not activated.

The water heater is designed to operate in air temperature of between 1"C and 70"C and for water temperatures of between 2"C and 25"C.

Figs. 2, 3 and 4 illustrate a practical embodiment of the valve hitherto described with reference to Fig. 1, and the same reference numerals are used with addition of a'.

In Fig. 2, dashed line 34' represents internal porting extending from the low pressure inlet side of the monoblock valve to the pressure switch assembly section 24'.

The practical embodiment of Figs. 2, 3 and 4 is used and functions in the manner hitherto described, and the flow of water through the monoblock valve body 10 is indicated by arrows A and B, arrow A indicating the flow of cold water through the valve body to the heat exchanger 26' and arrow B indicating the flow of hot water from the heat exchanger through the valve body. Only Fig. 4 shows the heat exchanger 26', which is directly mounted to the monoblock valve body.

Claims (10)

CLAIMS 1. A water heating control valve comprising a monoblock valve body with a water inlet and a water outlet and incorporating the following components:

1. an on/off water flow control valve;

2. a flow control valve for controlling the rate of water flow; and

3. a switch for controlling an associate water heater.

2. A control valve according to claim 1, wherein the monoblock valve body incorporates a mounting flange for a heat exchanger.

3. A control valve according to claim 1 or claim 2, wherein the water flow control valve comprises a solenoid or manually operable valve which acts as an electrical on/off inlet water tap.

4. A control valve according to claim 3, wherein the water flow control valve also acts as a stabilising valve, which detects and compensates for variations in inlet water pressure thus ensuring a constant rate of flow and hence constant outlet temperature at a given setting.

5. A control valve according to claim 4, wherein the water flow control valve has a volume go ernor.

6. A control valve according to any of claims 1 to 5, wherein the water heater switch is a switch assembly which senses pressure resuiting from the flow of water through a restrictor situated between the low pressure side of the valve assembly and the heat exchanger.

7. A control valve according to claim 6, wherein the water heater switch is adapted for connection of microswitches thereto for controlling heating elements of a heat exchanger.

8. A control valve according to claim 2 or any claim appendant thereto, wherein the heat exchanger mounting flange is associated with inlet and outlet flow fittings for the heat exchanger.

9. A control valve according to any of claims 1 to 8, wherein cold water entering via the inlet flows through the on/off valve the flow control valve and passes via the connector to a heat exchanger whilst water heated in the heat exchanger is returned to the valve body via the connector and passes to the outlet.

10. A monoblock valve body substantially as hereinbefore described with reference to the accompanying drawings.