gas rolls into burners& delay ignition

heat411

Cleaned burners ,cleaned pilot   gas pressure before valve 7.0 wc after gas valve 3.5wc  gas rolling out & also blows into burners

Tim McElwain

In other words

you have "flame roll out" and "flashback" along with a delayed ignition which means it comes on with a bang? Does it ever stabilize at any time?



How is your draft on the flue/chimney?



Do you have a combustion analyzer?



Is this a boiler or a furnace?



Are there any fans running in the building causing a reverse chimney?



Is the input to the boiler correct, have you clocked the burner at the meter?



You could have a blocked chimney, plugged heat exchanger etc?

 

Alan (California Radiant) Forbes

Also.........

check the gas orifices, especially the one that provides gas to the burner that has the pilot attached to it. I've seen this a couple of times where a spider's egg sack will block the orifice, preventing gas from getting to the burner and delaying ignition.

VictoriaEnergy

Keep cleaning

If the vent is working; the inside of the boiler's flue passages could be building up a layer of scale, dust, rust, etc that may be choking off the flow of exhaust trough the boiler.  If the piping is not in the way, taking the top of the cabinet apart is sometimes simple and gives the necessary access.