Hi guys , just joined can anybody throw any light on this for me please..............boiler was going to double flashing light fault , have replaced the metal Honeywell APS with the now plastic one . It will only go to ignition with the air tubes reversed ie from the venturi to the minus side of the switch. Have wired to 1 and 3 common and NO , the venturi is clear as is flue and the door seal is good.
What am I missing ??
What am I missing ??