The permananet pilot light on my Puma 80 lights ok when holding in the
gas valve and sparking the piezo but it goes out when slowly releasing
even after a few minutes. Water pressure is above 1 bar.

Changed the thermocouple but the effects are the same.

The diagnostic flowchart says 'suspect overheat thermostat'. Where do
I find this?

I see from other postings on this forum that there may be a manual
reset on some overheat stats/boiler models but it is not clear if this
exists on the Puma 80?

Is this the correct line of attack or should I be looking elsewhere?

Thanks for your help - my wife is longing for a shower as the major
gardening activities have also just started!

riverthames