Boiler won't turn off. Can anyone help?

[hs1972]

We're having problems with our Baxi boiler. When both the heating and hot water turn off on the controller the boiler stays on, and keeps firing. However the issue is that it does this intermittently, it will go for a few days and be OK and then the problem will start again. This problem doesn’t occur when water only is on. We’ve changed the controller but this hasn’t helped. Can anyone help?

[JLA]

have you checked your thermostat? maybe thats the cause and not the controller

[hs1972]

That's a really good point, we hadn't considered it might be the thermostat.

Thanks for responding so quickly - it's really appreciated!

Best wishes,
Helen

[SeanT]

What do you mean by keeps firing exactly?

[hs1972]

Hi Shaun

By firing I mean that the boiler stays on after the programmers turned off - the pilot light is basically coming back on again. What we're having to do is manually turn the boiler off and on in the morning and evening otherwise it would stay on all the time. It doesn't happen however if we've only got the boiler switched to hot water (as we had in summer) it's only when we've got the boiler turned to heating and hot water. Hope this makes sense?

Best wishes
Helen

[SeanT]

OK, so it is control circuit related - by firing, I thought you meant sparking for a start (which would suggest a knackered thermocouple or gas valve)

[watermead]

Need more details on the system for a more precise answer. Could be your motorised valve is sticking if it isn't the programmer, but depends on the type of valve and controls fitted.