Puma 80 Burner Problem-Injectors Self Lighting

[Simon3055]

This is one I have not come across before and I am wondering if anybody has and has fixed it. The fault is on a Potterton Puma 80 Boiler. The boiler operates normally on DHW and CH. However once it cycles off and stays dormant the burner injectors light up of their own accord. This takes anywhere from 30 secs to 3 mins. It lights with a "boom" so its obviously a gas build up. I would guess its using the pilot light flame. The burner only comes on with a pilot light sized weak flame and gas is obviously getting to them but how? I've taken off the Combustion Chamber cover and cleaned the injectors with a brush and tightened up the sealing washers. With the cover off the problem doesn't happen so the gas is obviously dissipating into the air.

One further clue is that once you turn off the gas supply and relight the pilot the problem only happens after the first cycle either DHW or CH. The burner won't light up until there is a demand placed on the boiler, as soon as that first cycle is over the problem returns.

Any ideas?

 

[Steelmasons]

You won't get any advice in here , call a gas registered engineer.

 

[ianmcd]

turn it off at the gas isolation valve below the boiler, or if you cant do that then turn the gas off at the gas meter and call an RGI, do not leave the gas turned on to this

 

[Gasguru]

Turn off the boiler, isolate the gas and stop using it NOW. It's a very dangerous fault easily found and repaired by a boiler engineer. It won't be a cheap repair though. You have clearly no idea of what you're doing.