Hi all,
Could anyone with a better understanding of the psychology of boilers than me give an opinion on this.
The boiler is a Baxi Bermuda back boiler. It's about four years old. It has had an ongoing problem with printed circuit boards - they "blow" from time to time.
The most recent PCB failure resulted in me sending the blown one to Geoff on here. He replaced a transistor on it - his opinion was that the gas valve must be faulty and drawing too much current, because the failed transistor was controlling the gas valve. We put the reconditioned PCB in and simultaneously replaced the gas valve. However the PCB still produced a lock-out. We adjusted the gas pressure on the new gas valve up and down to no avail.
In frustration we put the old gas valve back in. With the old gas valve, the now reconditioned PCB (and with everything demanding heat) the boiler now fires up, but only for about five seconds. The burners then all go off for a few minutes before coming on again for a few seconds, etc etc. Would this be a flame sensor problem?
What seems odd is (a) that the flame sensor and the PCB failure should coincide, and more strangely (b) why does the old gas valve produce some sort of response whereas the new one produces complete PCB lockout.
Any ideas very gratefully received, at the moment we're slowly replacing the boiler part by expensive part and getting nowhere.
(By the way, the "we" is because my brother is doing the hard work with me chipping in by phone).
Martin