Boiler switches on for 10-12 secs then goes off again

[HarrogateGas]

Thats not what i said............if the pilot is passing it will give the boiler a pilot ths 'confusing' the pcb. I changed a gas valve only 3 days ago for this fault.

 

[ChrisR]

Had one pilot, (Profile) doing that a month ago but it just sat there, no cycling!
The flue corrosion is a common fault. A retrofit kit is available from potterton, which fits easily from the outside so no need to take the boiler off the wall(phew!).

Does any heat get out of the boiler? I know it isn't on long but on CH only it would probably warm a rad or two. It isn't easy to get evidence of water flow,( though sticking a blowlamp against a pipe, with experience...!)

 

[ollski]

Yes a corroded flue will cause exactly that problem.

 

[ditmco]

Thanks Ollski. To previous threads, I have tried boiler again and there is definately water flow through pump. Rather than finding heat in a rad I have found that the pipes coming from the diverter valve have cooled (they were previously warm from conduction via emersion heater).

 

[ditmco]

Thank you all for your input - it was the flue causing the problem. Explanation is - the gases being expelled from the flue were not making it outside of the house and were therefore being sucked back in thus starving the main burner of oxygen.

Thanks again for all of your brilliant support.

 

[B.O.B DOLE]

once again the flame sensor