A heating engineer (the pilot light wouldn't stay lit), but that was some weeks ago and the system was fine until last week.
I'm happy to work on the plumbing/control bits, but not if it means making or breaking gas connections.
polybear
I'm having a problem (I think) with a BB 401 Back Boiler; the system is fully pumped with cylinder/tank & room stats and a 3-way valve. A faulty boiler pilot light thermocouple has just been replaced and all appeared well; however I'm recently finding that, when the room (or tank) stat is...