does anyone know why potterton netaheat boiler is still keeping some radiators warm even when heating and hot water is in the off position on the programer/clock , i have even actually removed the clock/programer but the boiler still kicks in and out to keep some of the rads on the ground floor warm (but not full heat as when the heating is on ) any ideas ?

john, November 2011

It sounds like you have a sticking Zone vale, although the valve is seen to be moving, the micro switch inside the valve is not shutting the system off.

Davea65, December 2011

could be auto frost stat, within the boiler, to stop it freezing, will switch on to keep the temp above about 5

SD, November 2011