Ideal Mexico problem

[glennhalstead]

Hi folks,
My boiler has developed a problem: It's always on. With the thermostat turned to cold the boiler is on and running, all radiators are hot. With the controller switched off the boiler is on. With the controller totally removed the boiler is on.

It's a Danfoss FP7801 controller but I reckon that's not particularly relevant if the problem persists with the controller removed.

Any thoughts on the cause?

thanks
Glenn

 

[shambolic]

Stuck zone valve.

 

[glennhalstead]

Hi Shambolic,
Thanks for your comment. Why would the boiler run with the controller removed? That seems odd to a layman like me.
thanks
Glenn

 

[Terrywookfit]

The zone valve micro switch is supplied from perm live not the programmer.

 

[ianmcd]

as advised you have a zone valve problem