Intermittent CH

[ian_uk1975]

Oil-fired, 2-zone (upstairs/downstairs) CH. Conventional (not combi) boiler. Drayton wireless programmer and wall stats.

The downstairs CH only comes-on intermittently... if I hit the boost button on the programmer, the red light comes on, but (intermittently) the rads stay cold. Usual workaround is to keep switching it on and off until, eventually, the CH comes on. The upstairs zone is fine.

I'm assuming this sounds like a sticking motorised valve?

 

[jackthom]

It is likely.
As a test try giving the valve in question a helping hand by opening it with the manual lever next time it fails to fire up the boiler..