I've had a search for this issue and I have seen similar but most say they have issues with the pilot light not coming on.

Our problem is that the pilot light comes on when it is suppossed to but the heating does not seem to light, it will (maybe) fire up the first time then after about 5 minutes it goes off.

Still the pilot light stays lit.

If I turn the immersion swithc off and the boiler for 10 minutes or so and turn it all back on then the heating will kick in although 5 minutes after it will turn off as before (and again the pilot light stays lit).

I've read that it could be the power board or the presure valve, I've also followed instructions that i should turn the boiler down to zero, trun it off, hit the red reset button underneath and turn it back on (this doesn't do a thing).

We had the pump replaced when we moved in to the house, we've had British Gas out to look at it TWICE!

1st guy replaced the plastic dial and told us the boiler would last another 10 - 15 years.

2nd guy seemed to resolve the issue (for a while) but told us that we would need a new boiler soon.

Any help on this issue would be magic.

Dave, March 2010

The first thing I would suggest is to avoid British Gas - stories on here strongly suggest that they are money sharks and use all sorts of wicked techniques to scare customers into spending money - you would do well to ditch them. When they behave ethically - and I'm sure they do from time to time - they're very expensive.

Your boiler is being "told" to fire up because the Pilot Flame is burning - for some reason the main Gas valve is closing prematurely. It is quite possible that the control electronics (pcb) is closing the gas valve because it "thinks" the pilot flame has gone out - if this is the case then the fault may be a defective pcb (about £120) - a partially blocked pilot flame injector (about £40) or a poor connection between the pilot flame sensor and the circuit board.

My guess - and it is only a guess because I'm an unqualified and inexperienced muppet - is that the control board has a heat-related fault - all is well when the pcb is cold - the boiler fires up as it's supposed to - the pcb gradually warms up and the fault (whatever it may be) closes the main gas valve.

If it were my boiler I would inspect the pcb for badly soldered joints or replace it. You may wish to call in an independent gas safe engineer.

Here's a link to a guy repairing his own pcb for a few pounds.

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

Take my answer here with a pinch of salt - I stress that I'm inexperienced and unqualified to provide any accurate or worthwhile help - just a retired computer engineer.

Good luck

Peccavi, March 2010