Potterton Promax System HE keeps cycling when OFF

[scimit]

As above. We have a Potterton Promax System HE boiler (GCNo. 41 590 69). I have noticed over the past few weeks that the boiler is cycling even when both the heating and hot water are 'off' at the controller. The boiler seems to start up, fire, then shut down, all in a period of maybe 20 seconds. This seems to happen every 20-30 minutes.

I've checked the controller is working correctly, which it is. but can not find anything in the servicing instructions for this sort of fault.

Anybody any ideas?

Many thanks

Val

 

[Agile]

It sounds like a failed switch in a motor valve and perhaps a wrongly connected pump.

Because its not an obvious senario it will probably need some with diagnostic experience to be on site.

Tony

 

[scimit]

Thats a good thought. I don't think it will be a wrongly wired pump as this is a new fault and the system has been in for three years. But I can imagine that a duff valve switch could do it.

Thanks, I'll have to do some investigating.