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  1. #1
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8

    Confused "Sweet" smell occasionally from vents

    Hi,

    First posting, and it's gonna be longish -- apologies in advance. Here's goes:

    As of 2007, we're the second owners of our 2002-ish ranch in Wisconsin. Previous owners had an Aprilaire 5000 filter box installed on the Bryant "Plus 90" furnace w/central air. Since our house was built well, but with cheap components, I'm guessing the HVAC is a the bottom of the range.

    At some point in the next few years, I noticed a smell in the house and eventually narrowed it down to the furnace fan. We had it cleaned, along with the a-coil, although the tech "picked up a bottle of coil cleaner" on his way over. The smell returned in a week. Not confident in the tech, and after net research, I installed a UV light over the coil, sealing up the joints in the plenum and close-range ducting with foil tape. The smell returned again after a week or two. Unplugged the 5000's electric grid, which some claim to emit an ozone-like smell, with no different results.

    Inspecting again, I noticed a sickeningly strong "sweet" smell on the expensive Aprilaire paper filter. I bought a replacement, which again lasted some limited amount of time. The smell almost reminds me of ozone, but somehow more organic. And it kicks my allergies into high gear almost instantly.

    I noticed that the fresh air intake to the return was flexible ducting (and very dirty), so I replaced it with rigid 4" and closed the damper, which leaves a small (1/4"?) gap, and added carbon filtering at the mouth of the intake outside. The smell still returns.

    I then installed a 2nd UV in the return. Same results. I moved the 2nd UV to be in front of the Aprilaire. The paper filter no longer smells, but The Smell has returned in the house. It doesn't matter if it's AC, heat, or just the furnace fan. Oh yeah, in this mess we also did a duct cleaning from what seemed like some good folk (they gave us maint tips, don't want to clean again for at least 2yrs, etc.). Also, there are times where the smell goes away for several weeks. I've tried correlating the occurrence to outdoor smells and local spore counts, but nothing conclusive.

    I'm done with the DIYing, but have no idea how to locate a competent tech. I've called a firm about mold/allergen testing, but at $300 plus $75 for EACH test (and I have no idea what to test for), that's not gonna happen.

    Thoughts anyone?

    TIA,
    Rich

  2. #2
    Join Date
    Oct 2011
    Location
    Ontario
    Posts
    5
    As per the AOP Rules only Professional Members * can reply with advice to the OP. Anyone may post and ask questions. They may even question the * member answer but not give advice or expand on the advice given. Please read these rules for a complete understanding. AOP Rules

    For those in our industry who wish to become a Professional Member, please click here and follow the instructions. Apply for Professional Membership
    Last edited by Chris_Worthington; 10-12-2011 at 06:19 AM. Reason: Non Pro

  3. #3
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8
    Quote Originally Posted by skilliam View Post
    As per the AOP Rules only Professional Members * can reply with
    advice
    to the OP. Anyone may post and ask questions. They may even
    question the * member answer but not give advice or expand on the
    advice given. Please read these rules for a complete understanding. AOP Rules
    For those in our industry who wish to become a Professional Member, please click here and follow the
    instructions. Apply for Professional
    Membership
    I've forgotten about that -- mine's already fixed, before we bought the house.

    Despite the reported potential health effects, I love the smell of ozone! (no, I never use ozone generators) But this smell seems organic. Swamp-like but sweet, without the decayed material smell.

    I realize that the kill ratio isn't great for the length of time something flying over the UV lights is exposed, but I'd think that fresh stuff must be pulling in from outside for the concentration to be increasing enough for me to smell it and for it to affect my allergies like it seemingly does.

    Gah -- I think I'm too close to this problem to think clearly about it anymore...time for bed anyway.

    Thanks for the reply!

    Rich
    Last edited by beenthere; 10-12-2011 at 06:34 AM. Reason: removed quote

  4. #4
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    You NEED to have your furnace heat exchanger thoroughly inspected ASAP as this is a symptom of failed/clogged exchanger.

    Call a Pro

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    You say that this smell is there regardless of whether you're running a/c, heat, or just the blower. At any rate, I'm with Chris...at the very least you should have your furnace heat exchanger checked for cracks. The odor could be residual soot, it could be something else and the exchanger is fine...but you need to at least eliminate the most dangerous potential first.

    Whoever you call to investigate the furnace should perform a combustion analysis on the furnace, and also measure the carbon monoxide levels in the home. This is serious stuff, don't let it slide.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    799
    is this smell year round or only when the heater is on?

  7. #7
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8
    The smell is year-round, but not consistent. It'll just show up and stay around for "awhile", then disappear for another "awhile". I should be keeping a diary on this...

    As far as the exchanger, could the intermittent nature of this smell be explained by a faulty one? I would think that it would be more consistent if that were the case.

    Even so, I will definitely have it looked at (coming up on heating season anyway), but that brings me back to my post -- how do I interrogate an HVAC business to pick a good one? Or do I just start with the largest ad in the phone book and work down from there? I'm not in an "Angie's List" area, either.

    Thanks!

    Rich

  8. #8
    Join Date
    Oct 2007
    Location
    Austin Texas
    Posts
    1,827
    Ask friends for a good recomedation for a contractor. You could also look at our contractor map to see if there is one in your area. Good luck.
    Nemo me impune lacessit.

    How much blood do I have to bathe in to get clean?

    Don't look down on anyone unless you're helping them up.

  9. #9
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    799
    Where is the duct work located? Attic, basement, crawl space?

  10. #10
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8
    Quote Originally Posted by Gross View Post
    Where is the duct work located? Attic, basement, crawl space?
    No crawl space in our house and no ducting in the attic either, so it's just in the basement. Last year we remodeled it and added more ducting for the new family room, den, laundry, and half-bath. Since the pattern of The Smell didn't seem to deviate from before the remodel, I don't suspect any of that work as being an issue. It's mostly rigid with flexible where it terminates at the drop-ceiling portion of the family room and bath.

    Thanks!


    Rich

  11. #11
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8
    Quote Originally Posted by John Culpepper View Post
    Ask friends for a good recomedation for a contractor. You could also look at our contractor map to see if there is one in your area. Good luck.
    Nice map! Although no one within 50mi, strangely enough. I will ask around, but I'm by far the most picky person I know when it comes to IAQ. Well, my nose and sinuses are the picky ones anyway...

    Thanks!

    Rich

  12. #12
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    799
    Do you have 16 y/O or older kids in your home? May sound silly but it's relevant.

  13. #13
    Join Date
    Oct 2011
    Location
    Wisconsin
    Posts
    8
    Quote Originally Posted by Gross View Post
    Do you have 16 y/O or older kids in your home? May sound silly but it's relevant.
    It does! But no older kids just yet. We've got a couple of kids <10 and a couple of cats, but that's it. Previous owners (5 years ago) had a large dog (golden retriever?) and no kids.

    Mind racing with ideas....Should I be checking the return air covers?

    Thanks!
    Rich

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