Potterton Suprima 80HE not starting

[smmjh11]

Hi my sister has a Suprima 80HE that is not working what happens is when I turn off the boiler thermostat to reset it and then turn it back on the lights go green on the burner on and mains on but then the red light comes on the lockout indicator this flashes. According to the fault diagnosis it should mean the air pressure switch is faulty. Is there a way of proving this as I know there is issues with the PCB board on these boilers. I assume the normal sequence to light up the boiler is air pressure switch then the fan starts then the ignition clicks and the burner comes on. Is the air pressure switch a common problem or could the indicators be leading me to the wrong diagnosis.
Many thanks in advance for responses to my query

 

[Mr Smyth]

Off the top of my head, I think that a frozen condense pipe would also show this fault (air pressure switch).

Check that the plastic pipe from the bottom of the boiler is not blocked due to freezing. Boil a kettle and pour it over any outside pipe.

If the pipe runs internally check its not also blocked.

Otherwise the air pressure switch in within the combustion chamber and will require a gas safe engineer.

The PCB problem is with the older Suprima not the HE model. Although no PCB is perfect. The fact that it is showing the fault is a pretty good sign.

Hope this helps