I have a Potterton Netaheat boiler - (not sure of the model number). This morning, although the system was turned off, the bathroom radiator - the first on the run from the boiler - was slightly warm.
It seems that the pump had been running for a short while. I know that this can happen just after the system turns off to dissipate excess heat in the boiler but have never experienced it when the system has been off overnight.
I'm wondering if the 'excess heat' switch in the boiler is faulty.

Any ideas?

Kevin, February 2006

Ah, be careful here. It may be one (if more than one fitted) of the motorised valves. If the electronic switch mechanism gets stuck, it will leave 'live' to the boiler. Suggest you keep an eye on it, when the system should be 'off' but the pump is still running push the mechanical levers on the motorised valve(s) and see what happens !

Kev, May 2006

poss pump overrun not working correctly.not turning off can be checked with multimeter its at side of gas valve

paul, March 2006