Hi, for about 3 months now I've had an intermittent problem with my Potterton Suprima 50L boiler. It's about 13 years old and has the new Siemens PCB fitted (possibly from new). The problem was that the boiler would go through its start up, fan and pump would start, 10 seconds or so later the boiler would fire up nicely, then exactly 7 seconds later it would shut down. After about 10 seconds of inactivity the sequence would start again. No faults would come up and the reset would never need pressed. Somehow these 7 second bursts were enough to heat the house.
After spotting this I did some digging to find out what was wrong as I assumed it'll only get worse and all the stopping/starting would eventually wreck the boiler.
Tried all the stuff a non gas guru can check, pump, flushed the system, 3 way valve, air pressure switch even replaced the PCB (2nd hand, eBay) still no joy.
Lastly decided, even though air pressure switch was working when fan running, to look in the flue and check for blockage whereby spotting a badly corroded inner pipe which would allow exhaust gas into the air inlet. 2 minutes and one old Heinz baked bean tin later and boiler working a treat. Will get new section of flue asap though. Can I fit this myself or does it have to be a gas registered person?
After spotting this I did some digging to find out what was wrong as I assumed it'll only get worse and all the stopping/starting would eventually wreck the boiler.
Tried all the stuff a non gas guru can check, pump, flushed the system, 3 way valve, air pressure switch even replaced the PCB (2nd hand, eBay) still no joy.
Lastly decided, even though air pressure switch was working when fan running, to look in the flue and check for blockage whereby spotting a badly corroded inner pipe which would allow exhaust gas into the air inlet. 2 minutes and one old Heinz baked bean tin later and boiler working a treat. Will get new section of flue asap though. Can I fit this myself or does it have to be a gas registered person?
