Hi need some help, i have a potterton profilr 50e boiler it works fine from cold but once it has heated the water and heating up it switches off and then when it tries to restart the fan runs for a short time then switches off then runs then switches off this carries on and on without boiler starting. i have changed the pressure switch, circuit board, boiler thermostat(one with dial) and pump overrun stat and tested overheat stat. still has same problem. when boiler is trying to start pump is running and two way valves are commanded open. it is driving me mad!! PLEASE HELP.

MARK ROSS, December 2008

i have just drained my heating system to fix a leaking radiator pipe.i have turned the water back on and blead the radiators.when i have turned the heating on the pilot light went on then off after 5 mins.when you push the button in to relight the pilot light it go,s back out when you take your finger off.could i still have an airlock in the system?

mike, May 2009

i also have the same problem . i just gave it a couple of good hard whacks on the side and it done the job. i think it could be a faulty valve that lets the gas into it. the only problem is , that i have to whack it every time i want it to start up .

mik67000, January 2009

I have exactly the same problem with my british gas 60F2 which I believe is a Potterton Profile.
have checked everything but still same problem.
I have found that if the casing is cracked open to allow more air in it works perfectly.
This indicates to me that it can only be the Pressure switch that is faulty.
I have tried adjusting the pressure settings but no luck.
An experts advice would be gratefully received.

Stephen, December 2008

Or even the door seal

Afterthought, December 2008

Once boiler warmed up, gas burner will not relight - yes?

Given all the things you've eliminated I think the symptom you describe with the fan running and then stopping may be down to fan/flue/pressure switch area. If the pilot light comes on the fan and pressure switch are working as they should but if the pilot fails to ignite then the pressure switch is not allowing it - thinks the fan is bad.

Could be that the flue and pressure switch pipes are good enough to operate the pressure switch when the boiler is cold, but once it has warmed up not enough differential pressure is being seen. I am guessing pipes and or the integrity of any seals and gaskets in the exhaust flue may be the cause. But just guessing.

Good luck...

Peccavi, December 2008