Boiler not shutting down properly

[GarryA]

Hi,

Poterton Performa 18HE

When the stat gets to temp I can hear the 2 pos valve shut off and usually the boiler then runs down for 2 mins then shuts off, sometimes though the boiler switches off instantly, which to my mind is not correct.

Anythings I can have a look out for?

Cheers.

[Ferg]

When the valve shuts the burner should stop instantly. What you hear then is the pump overrun circuit running the pump to disperse the heat. I would have thought it would be on a timer in the PCB. It MAY have a thermostat though. Either way, heat soak is the enemy of the low water content boiler.

[Ricky_M]

Can't picture the boiler, but the running down that you describe is probably the pump over running.


It will probably be controlled by a pump over-run stat, so times can vary.

[GarryA]

But shirley not as soon as the stat goes off? I can flick the boiler on and off using the stat, it will then overrun.