Like a lot of people on this site I have a problem with my potterton not lighting. I had the PCB board fixed by potterton on Dec 1st and it has been fine up until last night. Now it looks like the gas valve has gone. (it's sparking but not lighting at all). Potterton will charge another £170 to fix the problem meaning I've spent £340 in two months on a 3 year old system. Is there a cheaper way to resolve it? When I call a plumber they normally don't seem to have a clue how the system works and quote me even more whilst saying it may not resolve the problem.