I have a British Gas/Glow worm 330HE boiler fitted in 2006. Over the last few months a fault has been occuring. The system works fine normally I can turn the boiler one/off with the thermostat when the programmer is on but if the boiler happens to be running when the programmer goes off then the boiler/pump will not switch off and carries on heating the whole house all night! I can turn the boiler off and when I turn it back on it starts up again, I have to leave it off for several hours before it works properly again. If i turn the programmer back on then turn the stat down the boiler cuts out as normal, then when the programmer goes off all is fine. I am thinking boiler control unit? Any advice please?

Mark Robinson, January 2014

check the system zone valves does it have 1 or 2 if it has 2 one is for the heating and one for hot water it is likely that it is stuck in the open position. this will give a signal to the boiler that heating is in demand regardless of clock.what type of valve is it (make)and how many valves do you have

deggsy21, February 2014

Try removing programmer when it starts playing up,there should be 2 small screws underneath,just slacken off do not take them out and then hinge programmer up and off from bottom,if boiler stops you need a new programmer

toptrish, January 2014