baxi 105HE

[pnjohn68]

can any one help my boiler has a problem, when the heating tries to come on the fan/flue light flashes then after about 5 mins will start up but only heats for about an hour then shuts itself off also if the heating does come on when you run the hot water it shuts everything off and the light starts to flash, dont think its the fan as this seems to be spinning fine and the air pressure valve clicks when you blow into the tube, someone has suggested that it could be the circuit board, as some had a old style board fitted, my mother has the same boiler as me that was fitted a year before mine by the same guy and has had no problems my boiler is 2 years old

 

[nogoodatfaultfinding]

If you are sure the APV works fine then it is one of 2 things if it is not a condensor (you never mentioned that) then it is the PCB if it is a condensor then try a blockage in the condensate first especially if it only started in the cold weather.
Undo a condensate joint pressuming its push fit and blow down or alternatively put a jug of water down and make sure it comes out the other end.
If no resistance and all is clear its your PCB.