Drayton combi-stat thermostat - how to get it off the wall?

[caff]

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

 

[mikej2005]

Room stats often have a small screw underneath that fixes the stat to the back-plate, which is normally screwed to the wall.

With any luck you'll have a loose connection inside, because there's not much else you're going to be able to check for.

You'd be advised to isolate the electrical supply to the boiler before you start and be aware that you might lose any timings, depending on whether there is any battery back-up on your timer or not.

 

[caff]

Thanks. I fiddled about for a bit, then found that I had to pull the dial off (I had been trying to pull the whole of the front of the unit off) and there was a screw underneath which fixes the housing to the backplate.

No loose wires, but I had a poke around, cleaned some dust off the metal strip (not sure what it's called) that makes the conection and starts the call for heat.

I think it's working now, but it's been erratic for the last few days so maybe it's just going through a good patch!

 

[kevplumb]

but I had a poke around, cleaned some dust off the metal strip (not sure what it's called)

bimetallic