Potterton Envoy 80 working erratically?

My Potterton Envoy 80 works errartically also. Mine fails to fire up quite frequently and we are always having British Gas out to fix it. My wife says they say its somerthing to do eith the flue. I looked at the diagnostic message today and it kept showing 'F' indicating there was low gas pressure. This seems to fit with the ongoing failures as the pilot light fires up but it doenst hold the flame (andf then keeps firing for the cycle of four and then times out 't'.
Any ideas anyone

Jon B West London
January 2010

call out someone who knows how to strip down the boiler completly,heat exchanger may be blocked on flue side,replace flue hood seal,top gator seal,sump seal,ignitor and flame sensor seal,make sure syphon unit is clear,worth paying someone to do this who is familiar with envoys
paul conneelly@acwilgar.co.uk

paul conneely
January 2006