In message , Hugo Nebula
writes
My Potterton Suprima 30 was refusing to fire up for more than a few
seconds yesterday, so I followed Potterton's Fault Finding flow chart.
This got me as far as "are the two yellow wires to the thermister
(sic) shorted?", which was a no. The next but one step was "are the
two white wires to the temp control shorted?", which was a yes and
therefore "replace Electronic Control", by which I assume they mean
the PCB.

However, as part of checking, I inspected the wiring to the thermistor
and carefully pulled it in and out. On reassembling everything, it
now seems to be working as normal. Is it possible that it is the
thermistor not conducting heat properly rather than the PCB?

Unlikely I would have thought

Even if it doesn't have heat sink compound around it, being physically
held in place, there's bound to be reasonable conduction to it from the
immediate area.

What's the resistance at room temp and up at operating temperature ?

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--
geoff