Potterton subprima 60 (not the one with side pcb the pcb is at bottom of boiler)

[southcoastboile]

Went out to this one. Found locking out on air flow fault.
fan runs but no ignition most of the time. Sometimes will fire and run for around 40 secs before locking out on air flow.
dead tested aps and had continuity when I blew through it. Removed and cleaned Venturi, ran water through fan to clean impeller, quite dusty, sprayed heavily with wd40 incase it was running to slow. Still doing the same.

it locked out on air flow after firing red led flashing only on left hand side. Then it went back into operating mode again and went through ignition sequence without being reset. This made me think pcb.

what threw me though was after cleaning fan and spraying with we etc I removed both wires to aps with fan running and checked for continuity. It was open circuit so that made me think aps or fan at fault.

any ideas?

 

[gasmanrob]

Only issue I've had with the he is the spark gen failing in cold weather.

 

[southcoastboile]

I didn't look to see if there was a spark generator separately. Is it not part of the pcb?

 

[gasmanrob]

No separate unit

 

[southcoastboile]

That's another possibility then. I think there must be 2 faults though because surely if the fan was running fast enough and Venturi clear and Aps hoses okay the Aps should make and it didn't.

That at added to the fact that the boiler restarts itself after a lockout indicating pcb.

its one of those awkward faults.