Once started up the boiler runs ok until it is shut down by the time switch or the room thermostat. When the time switch or room thermostat calls for heat,the boiler switches on, the fan runs the pump runs but the burner fails to light every time.When it does not light if I unplug the multi-pin plug on the printed circuit board and replug it fires up. Or instead of unplugging I tap the whole mounting unit it also fires up. I have checked the boiler seal for leaks and none is detected. Can anyone help?

Dennis, February 2016

Here is a link to a Potterton 50e saga which may help you...

http://kaijaks.co.uk/blog/nick/2008/02/10/dodgy-old-boiler

It seems that electrolytic capacitors deteriorate and fail in a warm environment - and guess what? - boilers are a warm environment.

This chap fixes his boiler for just a few pence.

Tapping to get your's running suggests a bad connection or a poor solder joint - which amounts to the same thing.

Tap more gently and more selectively - it may get you to the root of the problem...

There's a pressure switch to sense that the fan is OK - if the fan or the switch is bad or the switch has a dodgy connection then the pilot flame will not light. If the case has a bad seal then the pressure switch may have trouble working.

Check out the link...

Good Luck..., February 2016