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Acrid furnace smell

October 29, 2012, 01:28:10 pm

Has anyone experienced this. When the front furnace is running it lights and runs fine but has an unpleasant odor that I've never smelt before. I cleaned the unit so it's not dust or dirt. It almost smell like it's not burning properly although it doesn't smoke. I replaced the sheet metal chamber where the flame burns because it showed signs of wear. This didn't help. I'm ready to replace it but a new furnace is $900.00! Yikes..

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Re: Acrid furnace smell

Reply #1 – October 29, 2012, 01:57:25 pm

Assuming you mean a smell inside the coach. If you can see the flame while burning and can detect any yellow flame, your furnace may be producing CO (carbon monoxide). While CO is colorless, and does not smell, incomplete combustion produces other products that do smell. It is possible that some of the CO and other gasses could be getting into the coach side of the heater and that is what you smell. An inexpensive CO detector along with the OEM stock CO unit can detect these harmful gasses.

It's also possible the fan is not operating correctly and is allowing higher than normal combustion temperatures that make non-metal components give off an odor. Check ducting for obstructions.

Pierce

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Re: Acrid furnace smell

Reply #2 – October 29, 2012, 06:07:50 pm

We have not had your furnace odor problem.

As you know, propane furnace has two separate air flows that do not mix:
1) Combustion chamber which brings in outside air expels the air outside.
2) Inside heater pulls inside air across hot heat exchanger and blows the
 warmed air into the coach's interior.

If you are smelling the odor from inside heat ducts, it may not be a problem with flame area. Maybe a dead animal, etc? With furnace off, do you smell it from a heat duct with a fan blowing into another furnace duct?

If the smell is only outside could a critter be cooking?

If the heat exchanger has holes and is allowing combustion gases into interior, it seems that a CO digital detector like (Kidde Model KN-COPP-B-LS) would show a problem.
We have two of these Kidde battery operated models with digital display, in our bedroom, to help prevent bad dreams.

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Re: Acrid furnace smell

Reply #3 – October 29, 2012, 06:29:15 pm

Suggest you double check the ducting... Years ago chipmunks and squirrels decuded to store acorns in our ducting. When the heat came on, we had toasted acorns a very acrid and slightly burnt smell

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Re: Acrid furnace smell

Reply #4 – October 29, 2012, 06:31:27 pm

Easy way to VERIFY that you have no connection between combustion chamber and interior is to find someone who smokes (getting harder and harder).

Have them blow smoke outside the furnace inlet (outside coach).  If you smell the smoke inside-- Houston we have a problem.

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