Peter, did you have any success in sourcing information for your potterton prima 4of boiler problem?
I have just noved house and the same boiler as yours is intermittently failing to operate. i haven't got a manual to help me in any fault finding procedure....do you have any contact info as to people with knowledge of these boilers?
Regards
Steve (scummins61@hotmail.com)
Steve Cummins, December 2007