I have a Hawk II Optima combi boiler which is around 10yrs old. I've pushed the selector switch to the disable heating position. We have the hot water on. I've used the dial to turn the heating temperature all the way down and I've turned the room thermostat all the way down. However the boiler keeps circulating water around the radiators - most of the time it doesn't heat up the radiators but sometimes it does. Any ideas why the cetral heating is being called when it is supposed to e deactivated and the room thermostat is turned all the way down?

Jeremy, September 2007

That's great - thanks for the advice. The water is only heated when the hot water tap is turned on so I thought it was strange that the central heating would be on the rest of the time (even if there was no heat generated). I've turned the radiators off and it seems to have stopped the central heating from switching on. I'm a little worried in the winter when we do want the central heating to come on that it will continually blast out heat.

Jeremy, September 2007

Hello !
This doesn't mean that your boiler is working all the time !
These symptoms could happen when it just finished heating the hot water ! Perhaps there is no " flowcheck device" on the radiators circuit , preventing a " thermo-syphon " move of some warm water !
Turn off the valves of the radiators or replace them by " thermostatic ( automatic ) ones ! sept 17-2007 JPh
Tha,ks for the feedback when fixed !

JPh, September 2007