Boilermate II green light on constantly

For some reason the green light at the bottom of my boilermate II stays on continuously so I have to turn off the boiler at the mains.
When it is powered on the hot water and heating work fine but I can`t regulate the temperature of the heating, the room thermostat in the living room has no effect whatever setting it is on. The Potterson boiler itself fires up every 20 minutes or so for about 10 minutes. It doesn`t seem to matter what setting the clock on the boilermate is on either so I have replaced it woth a brand new Grasslin clock and it doesn`t appear to have made any difference.

Any ideas would be greatly appreciated.

Jon

is your gas boiler thermostat set to maximum ?
turn off your heating set the boilermate thermostat to minimum and see if it shuts off.
it maybe a defective thermostat, try that 1st though.
hope this helps
mark.
www.gledhill-repair.co.uk

Thanks, I tried setting boiler to max and boilermate to min but the green light stayed on.
I even tried to calibrate it with the instructions on the front of the boilermate to no avail. Do you think it is likely to be the boilermate thermostat? (am I right thinking this is the dial on the boilermate controling the storage temp which has the capillary bulb thermostat attached by thin wire?). Is it best to change this before I start to look at the 2 PCBs on the front panel of the boilermate?

Regards

Jon

yes mate sounds like the stat to me.
let me know how you get on.
regards
mark.
www.gledhill-repair.co.uk

Cheers Mark, I just needed some expert advice but suspected as much.
I`ve ordered a new thermostat and will let you know the outcome after I`ve fitted it.

cheers

Jon

I received new thermostat yesterday and fitted it ok. Once the boilermate gets up to temperature the green light goes out and the downstairs boiler stops firing. Problem I have now is that I still can`t seem to control the heating from either the room stat or the clock on the boilermate (I bought a new Graslin clock a few weeks ago). Heating still comes on if the clock is set to off or set to timed and it`s outside the times for the heating to come on. In order to stop boiler calling for demand I have to reduce store temp setting on boilermate to turn the green light off.

Any ideas grateful

Jon