i have fault with my 24i combi. when demand on either ch or dhw is on, the boiler fires, lights but keeps on sparking, as if it cant sense the flame. i have tried replacing the sensing probe, made no difference. have checked the wiring on the control valve, and it seems fine. is there a part of the pcb that could be causing this fault? thanks

Tim, August 2009

new pcb req

Ian, August 2009

i forgot to say, it does go into lockout, it sparks, lights but keeps sparking then it locks out, cutting the gas. then the fan has the typical 3minute overrun. ive tried replacing the rectification probe, made no difference. if it helps, i checked if voltage was present on the probe, it is, but as soon as the ignition starts firing its gone and isnt back till its entered lockout. doesnt this need to be present for the flame to rectify it to DC?
thanks

Tim, August 2009

Think you've got a fault on your PCB. The boiler is recognising the ignition and boiler light up through flame rectification otherwise it would go to lock-out and shut down. It just not supressing the ignition. Check all your earths are okay first. If there okay you'll need to replace the main PCB.

John, August 2009