Thanks for replying. I'm not too good at this stuff - confess I can't see the lever you mention.
Will upload some pics of thermostat, schematic of layout and pics of the manifold to see if that helps.
Got made redundant on Friday, so don't want to call someone out if there's any chance I...
I have a Halstead Eden SBX 30 boiler with an underfloor heating system. There are 3 Danfoss programmable roomstats in different parts of the house. Two of them work fine; but the third one (in the living area & therefore most frequently used) is not triggering the boiler to ignite when it comes...