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
I have heard of this type of fault being caused by the hot flue gasses
drawing the air (oxygen) away from the boiler to quickly if the fan assist
is running on after the burn. The only test I can ask you carry out, to see
if this is the problem, is to block half the flue pipe with something, non
flammable of course, and run the boiler to see if it cures the symptoms. If
it is works, then you'll need to call out a CORGI engineer and tell him
what's happening so they can spill test the system properly after any
alterations are made.
This is only a test and not a full cure for this type of fault. It needs to
be fully investigated and fixed properly to allow you to run the system
Do you mean all night and operating or all night off duty?
If the boiler has an overheat stat it is usual to find this interrupts the
thermocouple and drops out the gas valve then when it has cooled off it
relights as normal. You have probably gone in at the expensive end first.
Your problem may simply be a failed control stat or a dodgy overheat stat
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