GB2320108A

GB2320108A - Pause Controller

Info

Publication number: GB2320108A
Application number: GB9725807A
Authority: GB
Inventors: Robert John Colin Matthews
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-07
Filing date: 1997-12-08
Publication date: 1998-06-10
Also published as: GB9725807D0

Abstract

A pause controller has a switch which can make (or break) an electrical circuit in response to the pressure, temperature, or velocity of water, or other fluid, at one or more positions in a circuit containing the fluid. The device also incorporates a timer 14, which causes the switch 12 to be reversed after a set time interval. The time interval might be adjusted with a programmer 10, or fixed by the manufacturer. The switch may be used to open and close a bypass valve 12 in a central heating fluid circuit.

Description

PAUSE CONTROLLER The invention relates to central heating systems, and the like.

Many central heating systems use hot water circulating through radiators. A clock or programmer is used to give time control of the system. In addition a room thermostat is often used so that if the air temperature is high enough the boiler is switched OFF even though the clock or programmer may be ON. The thermostat is placed in a room (or hallway) which is taken to be representative of the whole house (or of a zone of a large house). This is not wholly satisfactory in that a thermostat in a single position cannot reliably indicate whether or not there is, overall, a demand for heating from several different rooms.

In recent years, thermostatic radiator valves (TRV's) have become widely used.

These give individual control for each radiator according to the air temperature local to that radiator. Because on occasions all the TRV's could be closed it is usually necessary to fit a bypass to allow a circulation to be maintained when all (or most) of the TRV's are closed. In older systems the flow through a bypass was controlled by a simple gate valve, and this allows a flow through the bypass all the time, even though it would be unnecessary most of the time. Recently, automatic bypass valves have become available.

Normally these are shut, and no flow through the bypass occurs. But if most or all the TRV's close down, the bypass valve opens to allow flow through the bypass. The degree to which the valve opens is determined by the increase in pressure in the pipework and this reflects the extent to which the TRV's have collectively shut. So a flow through the bypass is likely to give a better indication of the need to shut down the boiler (because there is insufficient overall demand for heat) than a single room thermostat. When all (or most) of the TRV's are closed the present invention shuts down the boiler.

A room thermostat not only controls when the boiler should be shut down, it also controls when the boiler should be fired up again (ie, when the room temperature has fallen by a certain amount). The present invention refires the boiler after a certain time interval, the 'pause'.

The invention comprises a switch, which breaks (or makes) an electrical circuit in response either to the pressure, temperature or velocity of a fluid, or to the difference in pressure, temperature or velocity of a fluid at different points in a circuit in which the fluid flows, and a timer, which causes the switch to be reversed after a set time interval.

A specific embodiment of the invention will now be described by way of example with reference to Figure 1.

In this embodiment a switch is incorporated in the automatic bypass valve, so that when the valve is opened an electrical switch is activated to interrupt the electrical circuit connected to the device and to start the timer, thus initiating the 'pause'.

Figure 1 illustrates the use of a pause controller in place of a room thermostat in a common central heating system. Solid lines represent pipework, and dotted lines electrical wiring.

In Figure 1, hot water is produced by the boiler (1) and forced round the circuits by the pump (2). One circuit heats the domestic hot water in the cylinder (3). The other circuit heats the radiators (4 and 5). Zone valves (6 and 7) control the flow through these two circuits. The radiators are fitted with TRV's (8 and 9). Time control is by a programmer (10) with a connection to the mains supply. Further control of the hot water circuit is made by the cylinder thermostat (11) via a connection to the zone valve and thence to pump and boiler.

An automatic bypass valve (12) is fitted. Thus far, the system described is conventional.

The present embodiment of the invention has a switch (13) incorporated into the automatic bypass valve. This is connected electrically to a timer and switch (14), the switch making or breaking the electrical circuit between the programmer and zone valve 7.

When the TRV's close down (because the air around them is warm enough), the bypass valve opens (assuming there is no call for hot water, ie, valve 6 is closed). This throws the switch (13) and this action starts the timer and breaks the outside circuit between programmer and zone valve. The boiler and pump shut down. (With the pump shut down the bypass valve will close again.) When the timer has measured out the pause interval, it causes the outside circuit to be re-made, firing the boiler and switching the pump on. During the pause interval, the TRV's may or may not open depending on the heat losses, etc, during this time. If the TRV's have remained closed, the bypass valve will open once again and another pause will be initiated. But if some TRV's have opened, then hot water will be pumped through to the radiators.

In one embodiment, the pause interval (eg, 10 minutes) is set by the manufacturer of the device, but in another embodiment the interval can be set by the installer (eg, a plumber), or, in another embodiment, by the user (eg, a householder). A long pause cuts out unnecessary firing of the boiler (wasteful of fuel), but a short pause allows the system to be more responsive to the need for heat.

A further embodiment will now be described by way of example, with reference to Figure 2.

Figure 2 illustrates the use of a pause controller which is activated directly by a rise in pressure in the pipework of the system. It replaces part of the system shown in Figure 1.

In this embodiment the switch (13) is activated by the pressure of the water in the circuit and is not incorporated into a bypass valve.

In another embodiment the switch could be activated by a pipe thermometer. This thermometer could, for example, measure the temperature of the water in the bypass pipework. When the bypass was activated its temperature would rise and so cause the switch to be thrown.

In another embodiment, in a solar water heating system the switch could be activated by the difference in temperatures of the flow and return to a solar panel. When the sun was not shining sufficiently, the temperature of the flow from the panel might fall below that of the return into it. The switch could be activated by this to cause the pump in the solar system to be shut down for the pause interval of the controller.

Claims

1) A device which comprises a switch, which breaks (or makes) an electrical circuit in response either to the pressure, temperature or velocity of a fluid, or to the difference in pressure, temperature or velocity of a fluid at different points in a circuit in which the fluid flows, and a timer, which causes the switch to be reversed after a set time interval.

2) A device as in claim 1 in which transitory states of pressure, temperature or velocity of the fluid are ignored.

3) A device as in claims 1 or 2 in which the time interval is set by the manufacturer of the device.

4) A device as in claim 1 or 2 in which the time interval can be set by the installer of the device.

5) A device as in claim 1 or 2 in which the time interval can be set by the user of the device.

6) A device as in claims 1,2,3,4 or 5 which responds to the opening of an automatic bypass valve by way of some direct mechanical link between the bypass valve and some part of the device.

7) A device as in claim 6 in which the threshold for response can be adjusted to different degrees of opening of the valve.

8) A device as in claims 1, 2, 3, 4 or 5 which is incorporated in a boiler.

9) A device as in claims 1, 2, 3, 4 or 5 which is activated by a difference in temperature of the fluid at different positions in a solar heating system.