Central Heating staying on

[Martin007]

Hope someone can help. Our Central heating is coming on / staying on permanently.

As soon as power is applied to the circuit / system the pump starts running and the boiler fires up even if all controls are not calling for heat. During periods set as off on the main control panel it still comes on (and is even running when the main control panel is turned off).

At first I thought perhaps the frostat was calling for heat so turned it right down and then even disconnected it but it made no difference (? would disconnecting it have completely eliminated its effect of calling for heat?).

I've also removed the main control panel, turned the main house thermostat right down, turned the hot water cylinder thermostat down and then taken it off the tank. But still with all these controls not calling for heat the pump runs and the boiler fires up.

Any ideas anyone?

 

[gas4you]

Hope someone can help. Our Central heating is coming on / staying on permanently.

As soon as power is applied to the circuit / system the pump starts running and the boiler fires up even if all controls are not calling for heat. During periods set as off on the main control panel it still comes on (and is even running when the main control panel is turned off).

At first I thought perhaps the frostat was calling for heat so turned it right down and then even disconnected it but it made no difference (? would disconnecting it have completely eliminated its effect of calling for heat?).

I've also removed the main control panel, turned the main house thermostat right down, turned the hot water cylinder thermostat down and then taken it off the tank. But still with all these controls not calling for heat the pump runs and the boiler fires up.

Any ideas anyone?

Is this a fully pumped system with a 3 way valve or 2 x 2 port valves? If so I would suspect that the microswitch has gone on a valve head and is supply power to the feed to the heating constantly. If this is the case it will need a new valve head. I recommend getting it professionally inspected.