Basically system fires up, then when it reaches required temperature it cuts out - pilot and everything. There is nothing wrong with pilot, thermocouple etc. as it will stay lit all night.
I have fitted a new gas valve but this has not cured the problem. Does this sound like a problem with the PCBs? I have run the tests on these and they seem fine but the problem only exists for a very short period of time as you can relight the pilot and carry on.
Is it worth just replacing them (£150 or so) or is there anything else I could do?
Stony