Central heating has been fine until a couple of days ago when it stopped coming on, then would come on occasionally and randomly, and only at very high setting, e.g. 29C, although it clicks at around 14C.
As the hot water supply is fine and the pressure reading is correct according to manufacturer's manual, I'm assuming that the problem is with the room thermostat. Thing is, I can't get it off the wall to have a look. It's probably really easy but as I haven't done it before, I don't want to use force in the wrong place and break it.
Have tried a small screwdriver in the slots and holes in the casing but no joy.
Can anyone point me in the right direction?
Thanks in advance