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  1. #1
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,644

    High outdoor dew point = damp basement

    It that time of the year that outdoor dew points exceed 60^F in green grass climates. This data on the basement %RH verses the basements %RH. The finished basement has reached 69%RH. The house gets 80 cfm of fresh air ventilation to the mainfloor with the air handler "on" low. The lady that manages this home says this is enough of this "no dehumidifer" test.
    The air in the basement is affected by the outdoor dew point and the moisture from the occupants providing moisture source. The material in the home along with slab under the carpet is absorbing the moisture. As the material moisture content rises, the indoor %RH rises. At +60%RH, the basements starts to smell like a basement.
    Tomorrow the dehumidifier is maintaing <50%RH. The data is posted below via pdf.
    Regards TB

    May 2013 Wet basement data No dehumidifier.pdf
    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"

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,644
    Started the Ultra-Aire 70H in this home this week. The finished basement reached 70%RH without any need for air conditioning. We had a couple days of high outdoor dew point followed by cool wet weather with lower dew points. The dehu removed 20 gals of moisture in 50 hour of running.
    Basement seems ok at <60%RH and 65^F. I am adjusting for 55-50%RH as a setting on the dehu.
    Regards TB

    5 28 13 WI basement data-549418-72.pdf
    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"

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,644
    This is the last week in May in WI. The Dew point hit 70^F this week.

    Look at the pdf for all the details. The Ultra-Aire 70H operate +80% of the time to maintain <55%RH during peaks. No cooling loads this week.
    Regards TB

    WI May Dew Points %RH Basements Dehumidifier.pdf
    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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