Lennox Gas Furnace Intermittent Fire Up Noise


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Old 04-15-21, 06:59 AM
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Question Lennox Gas Furnace Intermittent Fire Up Noise

I own 8 year old Lennox ML193UH natural gas furnace. About once every 4-5 days when the burner fires up it will roar, similar to a jet taking off, for about 3-4 seconds. After the roaring start it will work fine for the next several days and perhaps 60+ ignition sequences. There are no error codes being set.
The 'roar' is about twice as loud as the normal noise of the furnace normal firing noise but as I said only lasts a few seconds.
Any suggestions as to what is going on.
Thank you
 
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Old 04-16-21, 09:14 AM
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Welcome to the forums.

Roaring is not common in a natural gas furnace. Normally you'd want to watch the furnace to see what the actual problem is. If it happens sporadically that can be difficult.

As a recommendation I'd have a tech remove and clean the actual burners and burner orifices.
If you don't have a service company.... check with your gas provider as they usual have good techs at very far rates.

 
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Old 04-16-21, 02:01 PM
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Thank you PJmax. Appreciate your input.
 
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Old 04-17-21, 07:55 AM
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Finally got the chance to hear the noise close up. A good description might be similar to the noise you hear when you blow over the top of an empty soda bottle. Louder and a little more raspy, only for a few seconds at fire ignition, then burn sounds normal.
 
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Old 04-17-21, 08:12 AM
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That has to be something directly related to the burner.
You actually need to watch the flame(s) to see what's happening.
 
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Old 04-23-21, 06:00 AM
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Pjmax - Spot on diagnosis. Replaced burner assembly and the noise is gone. The old burner was dirty and had some minor rust. perhaps could have been cleaned up but I am happy that I replaced the part.
Thanks again.
 
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Old 04-23-21, 09:52 AM
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It's not uncommon for them to have rust in them.
A professional cleaning addresses cleaning the burner completely.
 
 

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