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  1. #14
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Quote Originally Posted by energy star View Post
    Yes seal off those vents. Don't know why anyone would want to run an electrical appliance that consumes energy 24/7.
    Spring/summer/fall outside air dew points are higher than the basement/crawlspace temperatures. As the outside air infiltrates the home and crawlspace, the %RH in the crawlspace is too high. A dehumidifier reduces the moisture levels to avoid mold and wood rot. The dehumidifiers have dehumidistats that operate only during high %RH conditons. The amount of energy is small if the space is tight and the setting is in the 50-60%RH range. In many cases, the dehumidifiers are used to maintain <50%RH throughout the home.
    Regards TB
    Attached Images Attached Images  
    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. #15
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,823
    Very familiar. If you close and seal the vents off and put a vapor barrier down, your moisture problem will go away.
    Always here

  3. #16
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Quote Originally Posted by energy star View Post
    Very familiar. If you close and seal the vents off and put a vapor barrier down, your moisture problem will go away.
    I tried to avoid an confrontation on this issue, but I must make this point.
    The moisture level is a well sealed crawlspace will be slithtly above the outside dew point. There months of the year in all green grass climates where the outdoor dew point will be +65^F. This air slowly infiltrates the crawlspace. The temperature in the crawlspace will be 65^F-70^F, what will the %RH be in the crawlspace under those conditions? Well above the max 60%RH required to avoid any mold or wood rot. It will be 70-90%RH! I have repeatly data logged these type of situations showing the need for dehumidification during these various weather conditions. A week or two of these excess moisture conditons starts mold/rot in near perfect undehumidified crawlspace. Data log and post for proof of real moisture control for during wet weather with various temps.
    I suggest anyone doing this type of installation with or without a dehumidifier use a Remote %RH monitor to monitor the space to assure <60%RH throughout the seasons. Do not wait for the telltale odor, it is too late than.
    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"

  4. #17
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,935
    Got a good remote to recommend?

  5. #18
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,823
    If air is "slowly" infiltrating your or "the" crawl space, you need to seal it better.
    Always here

  6. #19
    Join Date
    Dec 2003
    Posts
    2,275
    Seeing duct and batt insulation sweating under my house for the first time ever. Ugggh...

    House is 50 years old and the plastic on the ground in the crawl space looks like poop, so replacing it now. Got about 1/2 done today in "tight" end of the crawl space. Not fun. Going to seal up the vents this week. Should have done this a long time ago. The previous owner bought these fancy ones that automatically open when its hot.

    I hope this will stop the condensation and think it will. If not I guess ill get a sante fe. They sound like the best.

    TB, can you run duct off the samller ones to get the air distributed around the crawl space better?

  7. #20
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    925
    http://www.supco.com/LOGiT%20Data%20Loggers.htm

    love these little babies ...trend temp/ humidity all year..

  8. #21
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Quote Originally Posted by bigtime View Post
    Seeing duct and batt insulation sweating under my house for the first time ever. Ugggh...

    House is 50 years old and the plastic on the ground in the crawl space looks like poop, so replacing it now. Got about 1/2 done today in "tight" end of the crawl space. Not fun. Going to seal up the vents this week. Should have done this a long time ago. The previous owner bought these fancy ones that automatically open when its hot.

    I hope this will stop the condensation and think it will. If not I guess ill get a sante fe. They sound like the best.

    TB, can you run duct off the samller ones to get the air distributed around the crawl space better?
    All of the Santa Fe dehumidifiers have a duct kit available. Any open crawlspace usually does not need a duct for distribution. If you have isolated areas within the crawlspace, a single duct blowing a portion the dry air to that area. I assume that is a pathway for the air to migrate back to the dehumidifier. The Santa Fe Compact II is 70 pints/lbs. per day which will maintain +2,000 sqft of well sealed space at <55%RH.
    During low a/c cooling load and +60^F outside dew points with a slight wind, a dehumidifier is needed to provide <55%RH. This will also have a positive effect on the entire home, lower %RH.
    Keep us posted.
    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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