Central Heating on all the time

[Pistol]

My central heating system has just started misbehaving. It's on all the time, the house is like a sauna. Checked room stat is turned down and programmer unit is off, but the boiler still fires up, pump runs, radiators are hot permanently. Any ideas? The oil-fired boiler is a Boulter Camray 90/110 about 5 years old.

 

[wilhelm]

try

if the boilers outside, there may be other issues...

 

[ricarbo]

You haven't been caught out by a froststat have you? e.g. boiler in an unheated outhouse, so could freeze.

 

[Pistol]

The boiler is in the house. You are suggesting the zone control valve is the culprit? I know that one end of the winding is permanntly connected to the live mains supply - if this were to short-circuit for any reason then I could understand the heating being on all the time. What if it simply sticks, could this cause the problem? Right now I'm having to manually switch the boiler on and off which is a real pain. Thanks for your help
Pistol.