The PCB commonly fails often giving one of the following symptoms:
Fuse on PCB blown - boiler does nothing.
Pump runs but fan not running or erratic.
Pump and fan run but gas valve doesn't open (but check air pressure switch).
Pump, fan & gas valve operate but no spark ignition.
Boiler lights but shuts down after a few seconds because it doesn't detect flame (but check electrode leads and condensate trap if conncted).
PCBs are available on Ebay.
Phil T, June 2010
