Ok thanks i have called in a registered corgi chap. I think its the pcb. I thought the fact it only occurrs in very cold weather and is fine in the summer might be some sort of clue.
I have a potterton boiler prima f which only plays up in very cold weather.It tries to ignite i hear the rush of air or gas then just dies down and tries again. This can go on for many attempts/minutes before it clicks in and fires up. It is fine in the summer and autumn and spring. Its only...