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  1. #1
    Join Date
    Mar 2012
    Posts
    16

    Carrier furnace - strong odor from outside vent when running

    good afternoon,

    I have a mid 90's Carrier furnace that in recent weeks the smell coming from the outside vent while its running has become strong and smells like combustion and a bit of propane like smell. I can feel the intake beside it pulling in air and both vents are clear. Its always had a smell when its first started up outside - but this smell seems to now continue outside whenever its running.

    All 3 visible burners seem to fire quickly and well when it starts up, and as far as I know the water seems to be draining out ok into the floor drain.

    No smell or CO is detected in the house or around the furnace, but I'm concerned about this smell as I'm wondering if its not burning properly.

    Any idea what may be causing this issue? Could it be a heat exchanger?

    Thank you.

  2. #2
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    2,107
    No need to wonder - it's NOT burning properly. Numerous things could be the cause. The heat exchanger is not the likely cause since you do not smell anything in the house. CO is odorless but other combustion byproducts have odors. It is time for you to call in a pro with a combustion analyzer to find out what is causing this potentially dangerous behavior.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,608
    Carrier 90? I'm gonna vote plugged secondary.

  4. #4
    Join Date
    Mar 2012
    Posts
    16
    Quote Originally Posted by kdean1 View Post
    No need to wonder - it's NOT burning properly. Numerous things could be the cause. The heat exchanger is not the likely cause since you do not smell anything in the house. CO is odorless but other combustion byproducts have odors. It is time for you to call in a pro with a combustion analyzer to find out what is causing this potentially dangerous behavior.
    Thanks - I've shut it down until someone has a look. I'm interested to know what it could be.

  5. #5
    Join Date
    Mar 2012
    Posts
    16
    Quote Originally Posted by BaldLoonie View Post
    Carrier 90? I'm gonna vote plugged secondary.
    Yes its a Carrier 9200.

    So why would it smell outside and not inside?

  6. #6
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    brown/black inside furnace exhaust ?? sulphur/putrid exhaust smell ??
    usually failing/plugged secondary hx

  7. #7
    Join Date
    Mar 2012
    Posts
    16
    Don't see any discoloration but definitely a bad smell outside.

    Is there any warranty on those parts ?think i t's just under 20 yrs so getting to the point if it's a crazy repair might just replace.

    Thanks again.

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,608
    Should have heat exchanger warranty but the wisest move is to replace at that age.

  9. #9
    Join Date
    Aug 2000
    Location
    Central Oregon
    Posts
    749
    My vote goes to low propane level. Only because I had service calls within a week of each other with the same problem and same solution.
    If you think our goverment is screwed up. You haven't lived in another country.

  10. #10
    Join Date
    Mar 2012
    Posts
    16
    This is a natural gas furnace but the exhaust smells propane like.

  11. #11
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    2,107
    I hope the serviceman will also confirm that the gas pipe is big enough.
    I had a service call a few years ago where the installing company used 30' of 3/8" O.D. copper tubing to feed a 100K Btu LP furnace. The secondary was plugged so badly that the burners melted the lens on the burner cover. The furnace was just under 10 years old.

  12. #12
    Join Date
    Oct 2006
    Location
    The Beach
    Posts
    747
    Please get it checked as soon as possible. Could be a danger to you and your family. Very possible the secondary stopped up.
    Blue Fox

  13. #13
    Join Date
    Jul 2009
    Location
    Ontario, Canada
    Posts
    913
    more than likely plugged secondary heat exchanger. I would advise not using that furnace until its checked. Do not inhale the exhaust fumes outdoors--carbon monoxide levels will be extremely high there.

    Had a case a few weeks ago, same as you described. Homeowners carbon monoxide detector was going off. Get there, and the roll out switch tripped, had a melted sight glass, and carbon monoxide level were over 5000+ppm in the exhaust.

    It should be covered under manufacturer's warranty, but not the labor. But as BaldLoonie mentioned, may be in best interest to replace furnace instead.

    Let us know what happens.....

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