Day & Night LPG Furnace Backfire

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Old 10-25-17, 09:11 AM
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Day & Night LPG Furnace Backfire

I have an 80's Day & Night furnace that after being dormant for several years I was able to fire up thanks to some help from skaggsjie. Now in the morning it starts up great but about every 5th cycle it backfires on start-up, enough to blow out the pilot light this morning. The burners are clean with a nice blue flame and I installed a new filter . This intermittent problem is driving me crazy. Any ideas? Thanks
 
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Old 10-25-17, 09:45 AM
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The burners are clean
How did you determine that ?

More than likely there are blocked holes near the pilot allowing too much gas buildup before ignition.
Usually means the burners need to be cleaned.
 
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Old 10-25-17, 10:16 AM
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I vacuumed the burners out a week ago and that made a big difference in operation. In the morning when I turn up the t-stat you can barely hear the furnace start. It cycles off and on fine for several cycles before it decides to backfire again. I can try cleaning it again. Any other ideas ? Thanks
 
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Old 10-25-17, 11:00 AM
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You need to visually check/clean the little holes where the gas comes out.
Especially near the pilot and the crossover area where the flame goes from burner to burner.
 
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Old 10-25-17, 02:46 PM
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I think you nailed it Pete. This time I pulled the burners all the way out instead of vacuuming in place. I'm embarrassed to tell you how dirty they still were. There was a time I would have fired myself over that job. I guess that it was burning so inefficiently that the un-burned gas would build-up over several cycles and then explode. I won't be able to test it until tomorrow morning because it's 70 deg. here in beautiful South Lake Tahoe today. Thanks for your help.
Tim
 
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Old 10-25-17, 02:59 PM
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Sounds good. It can be hard to see into the gas burner holes. You do need something small to clean the holes out depending on bad the rust is. A steel bristle from a bristle brush works good.
 
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Old 10-27-17, 07:18 AM
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Pete,
The last two mornings the furnace worked perfectly. Thanks again for your input.
Tim
 
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