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Thread: Wet and Smellie

  1. #1
    Join Date
    Sep 2004
    Posts
    5
    I have a new home -1 year old. This is our first summer in the house (South Carolina) and we began to experience a musty odor in early July. I bought a Rh gage and found humidity level of 75-80% on the first floor of our 2 story home. I also found some light mold on shoes and clothes in the master closet. The closet has an air vent and a ceiling fan already. The house has a 1/2 basement (block), with an approximately 2000 sq. ft. of crawlspace. The crawlspace has a full vapor barrier. A house inspection made Sept. 2003, just after moving in, found the crawlspace wood moisture content at 17-20%. A termite inspection in July 2004 found moisture content at 22-23% and noted some minor standing water due to condensation from A/C ducts.
    The house has Trane XR 12, 13 seer units -(1)5 ton for the main floor and (2) 2.5 ton units for the upstairs and basement. There are (2) Aprilaire 5000 electronic air cleaners on the 5 ton unit and an Air Screen 1000 on the upstairs unit. The musty odors seem to be most noticeable in the areas over the crawlspace as opposed to the areas over the basement.

    By running two portable de-humidifiers on the 1st floor and 2 in the basement, I have been able to lower the humidity levels to 62-65% and reduce odor somewhat.

    Actions I am considering:

    Bleaching wood in crawlspace and using fans to dry.

    Installing de-humidifiers in crawlspace

    Covering vents in crawlspace and adding A/C register

    Cleaning of in/out coil/pans

    Adding a wholehouse integral de-humidifier and humidistat

    A UV light?

    I need a sanity check and help finding a qualified pro to get this done. Thanks, B.B.

  2. #2
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,959
    Make sure the duct is insulated in the crawl space. uv lights installed on the supply close to the coils would be a good idea. Make sure they are on all the time. I would leave the vents open in the crawl space so it can be conditioned. make sure your not pulling return air from the crawl. A make up air kit would be nice too depending on how tight your home is. Hope this helps. You may want to have a load calc. done on the home. If the a/c is to large it will short cycle and not remove the humidity like its supposed to do. You will have a cool house w/ high humidity.
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  3. #3
    Join Date
    Nov 2002
    Location
    emerald city, sc
    Posts
    1,469
    where at in sc ? different places require different actions. is your vapor barrier sealed ? we have had the best results by taping the seams on the barrier and making sure the barrier actually goes up the walls a foot or so, then making sure all the crawlspace vents are closed. are you runnig your fan in the on position? if so set it in the auto position. are your airhandling units level, are the drains properly installed?
    i wanted to put a picture here

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    What size is the home,10 tons is a lot?High humidity can be caused by oversized A/C.Sweating duct can be caused by under sized ducts,due to low air flow.

    Check the entering and leaving air temps.,at the equipment.

    I'd check and post these,before spending money on the crawl space,though it could easily be the problem.Whats's the RH in the crawl?

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    Old thinking/new thinking. Allowing high humidity outdoor air to enter a crawlspace is old thinking. New thinking is cover the earth with plastic and close the outside vents to stop the humidity from entering your crawlspace. A 100 pint of whole house dehumidifier will control a 2,500 sq.ft. home including the crawlspace/basement. It will keep the home about 50%RH. The high efficiency unit like Ulta-aire will operate for a fraction of the cost of the residential units. The odor will go away in a week. This concept also will work with an oversized a/c. I just got back from Comfort-Tech and heard many contractors reporting success with this concept. Some are advertising and installing many systems.

  6. #6
    Join Date
    Sep 2004
    Posts
    5

    wet & Smelly

    Yes, I have been running fan in on position--Why auto?
    Size of house is 3300 1st floor--1300 2nd floor--1200 basement. House is in Upstate SC--Greenville/Spartanburg.

  7. #7
    Join Date
    Nov 2002
    Location
    Piedmont Triad area of North Carolina
    Posts
    2,300
    5800 sq.ft. and 10 tons of capacity...if you don't have allot of South/West facing glass, I would say the system is oversized drastically. Sounds like the 600 sq.ft./ton rule has been applied there. Only an accurate load calculation would let you know for sure.

    If you want to resolve the moisture problem in the crawl space, seal it as tight as you can. Block off all foundation vents, install and seal a 100% vapor barrier under the home. I live less than 2 hours North of you and we are having the same problems here. Hot moisture latent air is drawn into the cool crawl spaces where it immediately condenses on anything there [insulation, duct work, water and sewer lines, wiring...etc.]. This is always a problem on hot humid days in our area. The building code is causing the problem. If their is moisture under the home, we need to ventilate more...right!??? Adding more air amplifies the problem and does nothing to correct it. If the duct system is not sealed correctly, the system will draw this moist air into the home and cause high humidity also. I would have it checked thoroughly and resolve it before you have severe mold issues that you have to deal with.

  8. #8
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451

    Re: wet & Smelly

    Originally posted by jgbowman
    Yes, I have been running fan in on position--Why auto?
    Size of house is 3300 1st floor--1300 2nd floor--1200 basement. House is in Upstate SC--Greenville/Spartanburg.
    Operating the fan "on" re-evaporates the moisture collected on the a/c coil during the a/c off cycle. Makes your home wetter! One large central whole house with a sealed crawlspace space will reduce our dehumidifying cost and lower indoor humidity to 50%RH. Residential dehumidifiers are energy pigs costing $1.50/pint/month and they are enable to produce low humidities.

  9. #9
    Join Date
    Nov 2002
    Location
    emerald city, sc
    Posts
    1,469
    if you are in the upstate then your house is probably built over red clay, you will need a good sealed vapor barrier. definately turn the fan to the auto position.
    i wanted to put a picture here

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