lennox furnace pilot light explodes

[zippers3to29]

I just got home from hunting yeasterday standing by my furnace, and the dame thing shoot out a ball of fire, when it started but then it was fineheats good. so i cleand it all out took the burners out put it back to geather now it only dose it once and a while. can any one help direct me to a problem spot. thanks

[HayZee518]

does your furnace use an induced draft fan? It should be in the exhaust pipe to the chimney. I think what happened is that the induced draft fan didn't or doesn't run and allows the pilot gas to stay open building up an explosive gas mixture in the combustion chamber. when the igniter turns on this gas build up explodes.

[hvacwiz]

Originally Posted by HayZee518

does your furnace use an induced draft fan? It should be in the exhaust pipe to the chimney. I think what happened is that the induced draft fan didn't or doesn't run and allows the pilot gas to stay open building up an explosive gas mixture in the combustion chamber. when the igniter turns on this gas build up explodes.

If there is a draft motor not running the furnace will not fire at all due to the pressure switch not pulling in.

I would recomend calling a pro to take a look at this to make sure there is no danger such as a cracked heat exchanger.