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  1. #1
    Join Date
    May 2013
    Posts
    41

    Dehumidifier problem

    I have moisture on my windows in the winter months due to a tight house and no fresh air exchange. I can't afford a whole house solution now. A 20 year old stand alone dehumidifier that I borrowed to test removes lots of moisture in summer when the indoor temp is 76, but when the winter house temp goes below 70-71 degrees the coils freeze up. We keep the indoor temp at 68 in winter. Is that typical of these units, or is there something wrong with this one. Are new units better at indoor temps below 72 degrees?

    Thanks

  2. #2
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,973
    Teddybear will be along soon to better inform you...

    In the summer, my dehumidifier in the basement does not freeze-up when run on high speed even at 60 or 65F.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,360
    Quote Originally Posted by udarrell View Post
    Teddybear will be along soon to better inform you...

    In the summer, my dehumidifier in the basement does not freeze-up when run on high speed even at 60 or 65F.
    How can I not agree with you most of the time.
    This is a different issue. Houses with signicant winter window moisture problems are not getting enough fresh air or they have excessive indoor moisture source.
    Home need an air change is 4-5 hours when occupied. This amounts to 80-100 cfm of fresh air. If the occupants add moisture at about .5 lbs. per hour per person, expect about 1-2 lbs. hour humidification. If your home was 68^F, 40%RH, 43^ F dew point, any surface below 43^F will sweat.
    Outdoor air is dry during the winter and wet during the rest of the year. During winter with low outdoor dew points, more fresh air lowers indoor dew point much more efficiently than any dehumidifier could, beside you are getting enough fresh to purge indoor pollutants and renew oxygen.
    More fresh air when the outdoor dew points are lower than the desire indoor dew point.
    If you are getting enough fresh air during the winter, I suspect that you air not any fresh air during the mild calm weather of the other three seasons. For your home to be healthy during all of the seasons, you need 80-100 cfm of fresh air when the home is occupied. This means that you may need a humidifier during the winter and dehumidifier during the wet seasons of the year.
    In addition to the above, exposed earth in crawlspaces, large fish tanks, and high occupancy may cause the above problem. Fix the problem or more fresh air when the outdoor dew points are below the desire indoor dew point is a better solution than a better dehumidifier. If you insist on a better dehumidifier, consider the Ultra-Aire/Santa Fe dehumidifier line. They are a must for the 3 wet seasons of the year.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

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