My heating wont switch off?

yes, its not a combi, its behind the fire in the front room. I dont know anything about them so please bear with me.
What/where is the zone valve?
It does do that, the only way to switch it off is through the main fuse switch.
The timer for the hot water seems to be ok, its just the heating that keeps on running, weather its set to off/auto/on/once, it keeps firing up no matter what the digistat says.
Is this a diy job or a corgi engineer job?
thanks.

Lee Snowden
March 2008

I take it you have a cylinder ie not a combination boiler, then its your zone valve sticking open calling for heat regardless of timer or stats...

dpheating
February 2008