In message , Dave
Ramage writes
I sure that there is a running thermostat which is the one with the knob
and numbers.
If this does not cut out the boiler well before it boils then there is a
problem.

IIRC there is also a high limit over heat cut out - which is manually
resettable.

Both operate from a copper bulb inserted into a pocket into the heat
exchanger.

The fact that neither is operating is cause for concern.

Whether or not the problem is coincidence the problem needs attention.

Ed,

Thanks for your input. I did some testing with a multimeter and
concluded that the thermostat *was* openning after about 20 minutes,
but the PCB was ignoring this. CORGI guy is fitting a new PCB- this
time a new one, as the recon PCBs don't seem to be relyable!

Excuse me, that's a rather stupid statement.

I take it that the recon pcb you had wasn't one of mine, but anyway, the
stat cuts the power to the pcb, so it's highly unlikely that the pcb is
at fault. It sounds like someone's mis-wired it.
--
geoff