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Thread: IAQ Mega-Saga

  1. #1
    Join Date
    May 2006
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    - Bought 30 yr old house in SC with slight musty smell, uncovered crawlspace had some water after heavy rains.
    - A/C setup: Bryant condensing furnace and coils in crawlspace with side mounted 5" media filter, heat pump outside, flex and metal ducts. Competent HVAC contractor said sized properly.
    - Turned A/C system off for 8 days while on vacation, came back to BAD musty smell. Health deteriorated.
    - Extended downspouts >10 ft away from house to daylight, and sloped ground where needed.
    - Crawlspace stopped leaking, installed continuous poly vapor barrier going up walls to grade and sealed, poured 4" of concrete. Musty smell persisted.
    - HVAC contractor used AirAdvice for 1 week. VOCs and particles off the charts. CO and CO2 good. Avg RH in house 41%, Crawlspace RH 100%. Musty smell persisted.
    -Sealed all crawlspace to conditioned space gaps.
    - Replaced 5" media filter with Trane Clean Effects and Lennox PureAir (PureAir's media filter removed). Installed UltraAir 150H with fresh air duct.
    - Sealed ducts with Aeroseal (they claimed 2 square inches of leaks when done!!, 71 before). Sealed furnace with aluminum tape but still ingested crawlspace air (for sure more than ducts if Aeroseal truthful). Musty smell persisted. Health deteriorated further.
    - Sealed vents and installed portable dehum (40 pints/day) in crawlspace. Did not want to use 150H for dehum in crawl for fear of pressurization.
    - HVAC contractor used AirAdvice for 1 more week. VOCs off the chart. Particles, CO, and CO2 good. Avg RH in house 37%, Crawlspace RH 50%. Musty smell persisted.
    - Enviro engineer (PE) checked for point sources of smell/mildew/VOCs, found none.
    - Musty smell persists. Health deteriorating further.
    - Ideas welcome... I'm lost...near broke...depressed.

  2. #2
    Join Date
    Jun 2003
    Madison, WI/Cape Coral, FL
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    High humidity in the space is not the problem any more. The odors are coming from residue mold or a current wet spot. Serious mold growth may require thorough clean-up to eliminate slight odors. Water leakage around windows, plumbing or roof leaks all so cause musty odors. Condensation in walls on the insulation side of the drywall or in the insulation also cause odors. Shower/tub surrounds and under all sinks should be checked for leaks. Searching for strong odors using the human nose is effective. After being out of your home for several hours, (best nose in family) enter your home and go for the strongest source of odor. After a few minutes sensitivity decreases. Sniffing low on window trim and wall outlets when the wind creating positive pressure on the wall indicates the need for further investigation. Check all mechanical equipment, dehu & a/c air handler, for wet spots like drain pans and insulation.
    Operate the UA 150 with fan/fresh air ventilation continuously with fresh air ventilation "on". Short term, operate the a/c fan in the "on" mode to dry out all a/c-duct components. Are you using the uv light in the Lennox Pure air filtering system or did you replace the system? Advertising on Pure air claims oxidizing of VOCs. TB

  3. #3
    Join Date
    May 2006
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    Thread Starter
    Your advice is highly appreciated.

    Checked odor sources as suggested and found strongest in laundry room and hallway, only two with wallpaper!. Ripped wallpaper off, removed smelly residue glue with enzime cleaner, then hit walls with chlorine soln. Odor dramatically reduced, painting walls right now (fingers crossed til next rain when odor gets worst). 2nd strongest odor is chimney backdraft smell from registers, will talk to HVAC contractor to explain why we don't have positive pressure (I assume).

    Mechanical equipment and ducts checked, no evident wet spots. Running UA 150 and a/c fan as suggested. Using Pure Air solely for VOC reduction which requires UV lights reaction (pleated filter removed). Trane Clean Effects for particle reduction upstream of Pure Air. Pure Air went operational at same time as UA 150 and portable dehum in crawlspace, so don't know if I can attribute 50% VOCs drop to Pure Air (When I say VOC I mean only Isobutylene since AirAdvice only measures it, claiming correlation to TVOCs).

    Will post update soon. Moving in the right direction...

  4. #4
    Join Date
    Jun 2004
    4H: Hot, Humid Houston H.O.
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    >>Checked odor sources as suggested and found strongest in laundry room and hallway, only two with wallpaper!

    I wonder if this is a paper or a vinyl type of wallpaper. What I have read from Lstiburek (well recognized expert on building science) says vinyl wallpaper acts as a vapor barrier on the cold side of the wall, will attract moisture and often mold. Just one idea from an onlooker.

    Best of luck -- Pstu

  5. #5
    Join Date
    Apr 2004
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    T. Bear is right. The rest of your house is the likely culprit now. In the future, keep the system running 24/7, even on vacation. That 8 days without the system on is probably when the rest of the house went bad. Keeping the system on will pressurize the interior of the house to prevent infiltration from the crawlspace, making it easier to keep a lower RH.

    You may want to look at getting drainage for the crawlspace, as 100% RH means you have water, whether an open leak or a slow diffusion into the space through all of the walls. It happens in areas with a high water table, but can be mitigated with a good drainage system. Moving the downspouts >10' from the house is ok, but that water has to go somewhere when the ground can't hold it all. With the drainage you will still get higher RH than the rest of the house, but with the system on you will get very little into your house from the crawlspace.

    The rest of the house will need to be investigated for growth of mold. Do this now, and if it is ruining your health be aggressive with taking down drywall to find and eliminate it. Do not wait until next month to do it, as it will only get worse.

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