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Thread: Formaldehyde smell

  1. #1

    Formaldehyde smell

    I've just converted my charcoal furnace to propane / air - I tested it out today for the first time, cranked up the gas and air blast and got a choking formaldehyde smell from it. I'm assuming that this was due to decomposition of the propane by incomplete burning. Not enough air from my blower ? - the flame was yellow. Is it a blue flame I should be aiming for ?

  2. #2
    Senior Member
    Join Date
    Jan 2012
    Buffalo, NY
    I don't know what formaldehyde smells like. Maybe it's residue in your furnace or perhaps it's coming from the refractory. Charcoal and coal (you mentioned anthracite in your other post today) burn insanely hot but a propane furnace sets up at least somewhat different dynamics that may be burning tar or some part of your refractory that was previously unaffected. I don't know that burning propane creates an odor other than what that rotten egg additive they put in it might produce. I'll be interested to know what others think.

    Welcome to the forum and7!


  3. #3
    Administrator Site Admin
    Join Date
    Dec 2005
    Huatulco, Mexico
    This is what a propane flame should look like.

    When I die, Heaven can wait—I want to go to McMaster-Carr.

  4. #4
    Senior Member Wolfcreek-Steve's Avatar
    Join Date
    Apr 2014
    Central Wisconsin
    Yes, incomplete combustion will give you a very acrid exhaust gas. I've smelled it around poorly maintained forklifts, burns your eyes.
    What is that squeaking noise?

  5. #5
    Those are indeed aldehydes that are produced by incomplete combustion.
    Add way more air to complete combustion and the smell should disappear.

    Never breathe combustion gasses, even if they don't smell like anything!
    Provide ample ventilation and an exhaust system for any flame bigger then your hand.
    It's better to know something about everything then to know everything about something.
    Discovering the first everything is an adventure, discovering the second is a bore.

  6. #6
    Thanks for replying - Formaldehyde is also known as formalin when in solution. It's used for preserving biological specimens. I know the smell well from my days of working in a lab. It's the same kind of smell I've detected when my kitchen hob burner hasn't properly lit all around the burner cup. The refractory is ordinary fire cement and has been through over 30 melting sessions using charcoal / anthracite.
    As the optimum ratio is apparently 1:30 (gas/air), the problem might be that I can't match the gas flow with enough air on high settings. It was a terrible stench - burned the nose and made the eyes water. We couldn't tolerate it for more than a few seconds. I'm going to do a test run today with minimal gas feed and plenty of air, tempering up a new crucible, so we'll see what happens then.

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