Steam boiler issue

cpdodge1964

My boiler seems to lag before igniting 
it might just be me I think it ignites but 5 or 10 seconds later I hear the flames roaring 

Jamie Hall

Gas? Oil? Many controllers fir poiwer burners have a pre-purge where the combustion blower turns on for a few seconds -- anywhere up to 30 seconds, depending on the boiler/burner/controller combination -- before the fuel is allowed to come in and ignite. Could that be what you are hearing?

KC_Jones

If it’s electronic ignition it will turn on, fire to ignite the pilot, once the thermocouple is satisfied that the pilot is lit and stable, the burner will fire. So you can get a small ignition of the pilot then several seconds later the big ignition of the main burner array.

Is it possible that is what you are hearing?

Jamie Hall

KC_Jones said:

If it’s electronic ignition it will turn on, fire to ignite the pilot, once the thermocouple is satisfied that the pilot is lit and stable, the burner will fire. So you can get a small ignition of the pilot then several seconds later the big ignition of the main burner array.

Is it possible that is what you are hearing?

True for gas, @KC_Jones , but not for oil. No pilot. Fire up the spark, open the solenoid, and off you go, full song.

ChrisJ

Jamie Hall said:

If it’s electronic ignition it will turn on, fire to ignite the pilot, once the thermocouple is satisfied that the pilot is lit and stable, the burner will fire. So you can get a small ignition of the pilot then several seconds later the big ignition of the main burner array.

Is it possible that is what you are hearing?

True for gas, @KC_Jones , but not for oil. No pilot. Fire up the spark, open the solenoid, and off you go, full song.

From the little I remember about my oil burner it had a cycle before and after where it just ran the blower.

It could've easily been 10 seconds before it lit.   I think it had a solenoid to turn the fuel off so it could run the blower without pumping fuel.  I want to say they called it pre and post purge.

But I'm trying to remember something I knew little about even 13 years ago.

That was a 2004-ish Beckett AFG. 


That said any burner, oil or gas that has delayed ignition issues could be very dangerous.  If you're not sure and are concerned you should have it looked at even if just for normal maintenance.

Jamie Hall

Right on, @ChrisJ , all the way through. The only thing I could add is that the pre purge and post purge can usually be varied in the controller -- and will be longer in bigger burners (usually).

TwoTones

I have a standing pilot atmospheric gas burner that initially starts with a low flame for about 5 secs and then ramps up to full, normal part of the cycle..