Propane Furnace Smell Inside

[Dr_Snooz]

Hi everyone. I'm working on a very old Hydro Flame FA 7920 propane furnace in my 1993 Lance camper. The furnace worked great several years ago when I stopped using it. I'm ready to use it again, but the furnace now stinks up the interior with the smell of propane exhaust. I completely disassembled the unit and removed two bug nests, one from the burn box itself, but it still smells up the interior. I bought a new CO detector which hasn't uttered a peep, but still, the smell isn't healthy. The furnace itself is in great shape. It fires right up and heats great. There isn't any rust or other decay anywhere, though the blower fan bushings do howl a bit from time to time. Any ideas what I can do to fix this? The beach is calling my name and I can't answer...

Thanks!

 

[gwinger]

The smell may be nothing more than accumulated dust in the furnace and ductwork getting hot. Even our house furnace has an odor when first starting it in the fall.
Is you detector dual purpose CO/propane? A CO detector doesn't measure propane.

 

[CharlesinGA]

Are you smelling the foul smell of Mercaptan that is used give propane and natural gas their smell? or are you smelling exhaust smell of combustion. CO is odorless and colorless.

Are your CO and LP detectors both within their life limits and test properly?

Charles

 

[RayIN]

Still at the beach____?

CharlesinGA, did you get snow?

 

[CharlesinGA]

Snowing good for 3 hrs now.

Charles

 

[Dr_Snooz]

Thanks for the replies. It smells like propane exhaust, so Mercaptan that's been through the combustion cycle, I guess. I let the furnace run overnight to burn off any residuals. The next morning, there was a pronounced propane exhaust smell. The CO monitor is new. The propane alarm failed years ago, and I haven't gotten around to replacing it yet. I'm perplexed how I could get exhaust smell without CO. Just wondering if anyone has heard of such a thing before. I don't want to replace the furnace only to learn that an errant breeze is still blowing the exhaust inside.

 

[TheBar]

If the smell is strong outside some outside air may be carrying the smell inside. The propane supplier in our new neighborhood uses too much Mercaptan and stinks up the whole neighborhood. We have a propane fireplace and just the pilot light burning stinks up our house. I've also noticed old propane smells worse too.

 

[Gr8bawana]

When I replaced the fan in our travel trailer I didn't notice that I had knocked a section of the seal that separated the fan side from the exhaust side on the furnace door.
Once I replaced the seal the exhaust smell went away.

 

[Gary RV_Wizard]

The CO monitor is new. The propane alarm failed years ago, and I haven't gotten around to replacing it yet. I'm perplexed how I could get exhaust smell without CO. Just wondering if anyone has heard of such a thing before.

You only get CO if the air supply to the furnace burner is inadequate or some other combustion problem. A properly running propane burner won't emit CO - just CO2 & water and maybe a few stray hydrocarbon molecules that may stink. You need a LP gas sniffer for that, not CO.

The most common reasons for smelling exhaust fumes are:

• A hole in the top of the burner chamber, allowing fumes inside the chamber to mix with the circulation air that flows over the top (the heat exchanger).
• A faulty gasket in the exhaust & combustion air tubes to the outside, allowing exhaust to stray out inside the furnace shell
• Some sort of exterior opening allowing the exhaust outside to creep back inside.