GB2314914A - Valves in hot water and space heating systems - Google Patents

Abstract

In a system providing domestic hot water and space heating, a motorised valve 1 is provided in the flow line from a boiler 6 to the radiators, and a spring-loaded bypass valve 2 is provided in series with a heat exchanger 3 which heats the domestic hot water. If there is no demand for domestic hot water, the motorised valve 1 is open to the heating circuit, and hot water is pumped by pump 4 to the radiators. A demand for hot water is sensed by flow switch 11 on the secondary side of the heat exchanger 3, which closes the valve 1. The spring-loaded bypass valve 2 then opens to allow flow through the primary side of the heat exchanger 3 back to the boiler 6. On cessation of demand for hot water, the flow switch 11 returns control to the motorised valve 1 causing it to open, and allowing the bypass valve to close. If thermostatic radiator valves are used in the heating circuit, the spring-loaded bypass valve also maintains a set differential pressure across the system, and prevents pump overload by providing a flow path via the heat exchanger. The boiler 6 may be provided with a thermal store 7.

Description

"Improvements to Combination Boiler System Controls" I, NICHOLAS JULIAN JAN FRANCIS MacPHAIL, a British Subject of La Girouette, Grandes Rocques, Guernsey of the Channel Islands, do hereby declare the invention for which we pray that a patent may be granted to me and the method by-which it is to be performed to be particularly described in and by the following statement: THIS INVENTION RELATES IMPROVEMENTS TO COMBINATION BOILER SYSTEM CONTROLS It has been common practise in combination boilers utilising thermal store and heat exchanger to utilise either two motorised valves, a three port motorised valve, two pumps or a three port reversible pump to provide the necessary control means for the heating system and hot water supplied by such a unit. The present art involving these types of controls generally requires multiple relays, complex electronics, multiple thermostats and very complex wiring and switching procedures and are difficult for owner, installer and service engineers to comprehend.

Component number and cost is high and component space requirement is large. If a heating system with such a boiler incorporates thermostatic radiator valves it is now-a-days common practise to incorporate a spring loaded bypass valve to avoid system differential pressure variation and system noise. This type of bypass valve has to be added to the above systems at extra cost to the installer and end user.

It is the aim of the present invention to improve or obviate the above mentioned problems.

According to the present invention there is provided a motorised valve to provide control of the heating circuit with a spring loaded bypass valve which in conjunction with the motorised valve provides control of the flow of heated water either through the heating system or the hot water heat exchanger of a combination thermal store boiler.

Preferably said motorised valve and spring loaded bypass in conjunction with the combination boiler's inbuilt controls together with any room temperature control comprises the complete system control allowing priority to hot water as is required by this type of combination boiler.

Advantageously said motorised valve and spring loaded bypass valve carry out the control functions both for the heating circuit and the hot water circuit while at the same time providing the system bypass required by most modern thermostatically valved heating systems.

Conveniently the invention may be sited inside or outside a boiler casing.

In a preferred form of control with both channels of the programmer calling for heat and the room thermostat calling but with no demand for hot water, the heating circuit motorised valve opens to provide heat to the heating circuit. The spring loaded bypass valve, fitted in series with the domestic hot water heat exchanger on the bypass, is set to a slighter higher resistance than the heating circuit and retrains closed, thus providing full output to the heating circuit. If the flow switch sensor provided on the cold mains water supply side of the domestic hot water heat exchanger is activated by the operation of a tap then the power to the motorised valve is removed, closing the motorised valve and increasing the resistance across the spring loaded bypass valve beyond its set point causing it to open and pass the full heat output from the boiler through the primary side of the heat exchanger to enable it to provide hot water to tap. When the flow of water to tap ceases the power is reinstated to the heating motorised valve providing heat to the radiator circuits again before a noticeable drop in output at the radiators is observed.

Advantageously the motorised valve may be any suitable commercially available motorised valve having two or more ports.

Conveniently said motorised valve may have switchgear incorporated in its actuater.

Advantageously the spring loaded bypass valve may be any suitable commercially available spring loaded bypass valve.

Although this invention is described in its application for a combination boiler having thermal store and heat exchanger it should be understood that it may be used in any heating system where priority to hot water is desired. It should be further understood that although the control configuration described in the following drawings uses easily commercially available components with switchgear, these control components are only given by way of example and can be replaced by, for example, solid state circuitry. Other boiler control considerations may make it desirable to add in low limit thermostat control to prevent excessively low temperature water returning to the boiler causing condensation damage. Expansion, safety and venting means would normally also be incorporated in the boiler.

In order that the invention may be more readily understood and so the further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagramatic representation of a form of the present invention showing a typical pipework layout.

Figure 2 is a diagramatic representation of a line only electrical circuit showing a control system as may be used to control the present invention.

Referring firstly to Figure 1 of the accompanying drawings: within a boiler casing shown dotted, the motorised valve 1. is shown on the flow to a heating circuit. On the boiler side of the motorised valve 1., bridging between the flow and return of the heating circuit is a spring loaded bypass valve 2. in series with a heat exchanger 3. for providing hot water to tap. A circulating pump 4. fitted with isolating valves 5. is provided to draw water from the boiler 6. shown in series with a thermal store 7. (It should be understood that the thermal store 7. may be incorporated within the boiler jacket 6. It should be further understood that the heat exchanger 3. may be incorporated within the thermal store 7. or if the thermal store 7. is incorporated within the boiler that the heat exchanger 3. may be incorporated within the boiler). Upon the motorised valve 1. being actuated by the control system to provide heat to the radiator circuit while there is no demand for domestic hot water, the motorised valve 1. opens to the heating circuit. The spring loaded bypass valve 2. is set to remain closed at a differential pressure slightly greater than that created by the fully open resistance of the heating circuit so that under conditions of full heating circuit demand with no hot water demand the bypass valve 2.

remains closed.

On demand for hot water to tap a flow switch 11. on the secondary side of the heat exchanger senses this flow and closes off the motorised valve 1. The differential pressure increases across the spring loaded bypass valve pushing it open and causing the flow that has been lost around the heating circuit to now pass through the heat exchanger 3. via bypass valve 2. and to complete the circuit via the thermal store 7. and boiler 6. On completion of demand for hot water to tap the flow switch 11. returns the power to the motorised valve causing it to open allowing the spring loaded bypass valve 2. to close until such time as heat demand for domestic hot water to tap occurs again.

If thermostatic radiator valves are used as the heating system control the above mentioned spring loaded bypass valve also fulfills its normal function of maintaining the set differential pressure across the system to reduce system velocity noise at part load and to prevent pump overload by providing a constant flow path via the heat exchanger.

Referring now to Figure 2 there is shown an electrical circuit diagram in line only form for clarity as might be used to control the present invention in which fuse and isolation 8. provides switching and protection. Programmer 9. provides time control to both heating and hot water. The heating circuit is provided with temperature control either in the form of a room thermostat 10, or the thermostatic valves (not shown).

Flow switch 11. is provided to pass full thermal output from the boiler to the heat exchanger to provide hot water to tap when a flow to tap is actuating it. Pump 5. and boiler 6. run to provide circulation of the heated primary medium on demand from the heating and/or hot water demand side of the controls. It will be seen by following the functions of these controls that the motorised valve 1. on the heating system circuit opens on demand for heat from the room thermostat 10. or directly via the programmer 9. if the thermostatic radiator valves (not shown) are used as a system control. The motorised valve 1. is deactuated by the flow switch 11. when hot water flow to tap is detected.

Pump 5. and boiler 6. are run on demand from the motorised valve 1., the flow switch 11. and/or the hot water channel of the programmer 9. If the programmer 9. is off on both heating and hot water channels, for instance at night time, the pump 5. and boiler 6. will still run on demand from the flow switch 11. to provide hot water to tap conditional on heat remaining in the boiler and heat store.

It should be understood that although the above described control system uses a volt free contact programmer and a change over contact flow switch this would not preclude the use of volt on contact programmer and s.p.s.t. flow switch which would be possible with the use of relays.

It should be understood that the relevant positions of the heat exchanger pump, motorised valve and spring loaded bypass valve could be repositioned on the return or the flow to suit system circumstances.

Claims (6)

1. Means consisting of a motorisec valve ana a spring ioaoeo bypass valve to provide control of a space neating system ana not water system.

2. Means according to Claim I whereby the motorised valve and spring ioadea bypass valve carry out the control functions for a space heating system and hot water system while at the same time providing the automatic bypass tor space heating systems incorporating thermostatically valved radiators.

o. Means according to any of the proceeding claims whereby the saia motorisea valve and spring loaded bypass valve is sited insiae a boiler casing.

4. Means according to any of Claims 1 to 3 wnereDy the motorisea vaive ana spring loaded bypass are sitea outside a boiler casing.

5. Means according to amu pt Claim I to 3 whereby saia means is incorporated with a combination bo@ler.

6. Means according to the preceding claims whereby the said means is incorporated in a heating control system with priority to hot water.

T. eans according to the preceding claims whereby the saia means is incorporatea in a heating control system with priority to space heating.