Uncontrollable heating !

[puguser191]

Hello all - and HELP please

I have a problem with my central heating now that the days are getting warmer- typical....

I have a pumped s plan system with separate room stat.

The problem is that my room stat is down at minimum, and the controller is currently on its 'off' cycle (ie not due to come on due to the timer) both demand lights on the tempus 6 timer are off (red lights not showing) yet my boiler is steady at 75 deg and all the radiators are hot (or feeds to the individual rad valves are)

Any idea what might be causing this- I imagine the CH valve must be stuck open to allow circulation ??? but why is the boiler staying on?

Thanks in advance

 

[Doc955]

If the CH zone valve is jammed in the open position, it will be calling for heat from the boiler as the 'call for heat' signal comes from a microswitch activated by the valve's motion.