Heating randomly turning off

Hi all,

Our heating randomly turns off once or twice a day, usually after it's been on for a few hours. E.g. it's just happened now at 6pm having been on since 3pm. Only realised because the house starts to chill down, then check the stat and it's 2 degrees under temp, rads are cold and the boiler isn't on.

Only way to get the boiler to fire up again is to turn the power to the whole circuit (boiler, programmer, pump etc) off for a few seconds and on again. Resetting just the boiler itself doesn't work, which I hope suggests it isn't the boiler? But what could it be?

We've actually just had the boiler replaced. Had the problem with the old boiler too but more frequent, would have to reset the system 3 or 4 times an evening! Thought the new boiler would sort it but it hasn't, though it is a bit less frequent. Boiler needed replacing anyway as it was a 25 year old Potterton, but I just can't think why this is still happening with the new boiler (Worcester Bosch 24ri).

Any ideas would be much appreciated.

Thanks,

Rob

You don't have one of those weather compensation units fitted to your heating controls do you? There was also another annoying unit you could wire in that cycled the heating on and off at preset intervals to save gas or something, trouble is if it's cold it stops you getting any heat! I forget the name or make, I've never seen one fitted.

Thanks Freddo, don't think we have a weather comp unit, but we do have a Honeywell CM907 programmable stat which I sometimes think is a bit too clever for it's own good! Heating went off at 6ish again last night but the flame icon was on on the stat. However, I turned the stat to "Off" and then back to "Auto" and the boiler came on (whereas resetting the boiler doesn't do anything) which starts to point to the stat being the culprit... I think! It's the only thing it could be I think as otherwise it's a very simple system. Perhaps I need to catch it in the act tonight and pop a multimeter on to see if it's actually calling for heat when that flame is on but boiler is not. Very strange, now I think about it it started happening when we replaced the stat, but we also moved the old boiler and replaced a pump and zone valve at the same time so I didn't immediately assume it was the stat (thought it was more likely the boiler on last legs).