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  1. #1
    Join Date
    Jul 2008
    Posts
    5

    Basement Dehumidifier System Design

    I'd like to get feedback on the following design for my basement:

    My basement is about 2500sqft with drop down ceiling. Summer months RH is 60% and I wish to bring this down to 45%.

    I installed an Aprilaire 1720 an it is over working. Howver, it almost never shuts off. Therefore, I also bought a Ultra-Aire XT150. I also have a Panasonic WhisperLine™ 440 CFM In-Line Fan.

    I have 2x2 open grills in the drop down ceiling so I can easily draw air in without dedicated vents.

    I am considering 8" tapping the Panasonic into the existing ductwork so that the WhisperLine™ 440 CFM In-Line Fan exhausts air outside every few hours on a timer. I will install a normally closed damper between the Panasonic and the HVAC ductwork so that this only opens with the Panasonic on, drawing air from the duct vents already installed in the ceiling. Will the negative pressure consequence in the basement here be a good thing, drawing dryer air from the upper floor?

    Install Aprilaire 1720 with its inlet coming from a 8"T above the drop ceiling and its outlet ducted to a 8"T to above the kitchen

    Install UA XT150 with its own return via a 10"T on the other far side of the basement and tap the supply side of UA to the HVAC ducting. I would also install a 6" fresh air to the UA as well.

    Your suggestions and feedback would be appreciated.

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Quote Originally Posted by cgharibo View Post
    I'd like to get feedback on the following design for my basement:

    My basement is about 2500sqft with drop down ceiling. Summer months RH is 60% and I wish to bring this down to 45%.

    I installed an Aprilaire 1720 an it is over working. Howver, it almost never shuts off. Therefore, I also bought a Ultra-Aire XT150. I also have a Panasonic WhisperLine™ 440 CFM In-Line Fan.

    I have 2x2 open grills in the drop down ceiling so I can easily draw air in without dedicated vents.

    I am considering 8" tapping the Panasonic into the existing ductwork so that the WhisperLine™ 440 CFM In-Line Fan exhausts air outside every few hours on a timer. I will install a normally closed damper between the Panasonic and the HVAC ductwork so that this only opens with the Panasonic on, drawing air from the duct vents already installed in the ceiling. Will the negative pressure consequence in the basement here be a good thing, drawing dryer air from the upper floor?

    Install Aprilaire 1720 with its inlet coming from a 8"T above the drop ceiling and its outlet ducted to a 8"T to above the kitchen

    Install UA XT150 with its own return via a 10"T on the other far side of the basement and tap the supply side of UA to the HVAC ducting. I would also install a 6" fresh air to the UA as well.

    Your suggestions and feedback would be appreciated.
    Usually the moisture content in the air on the main floor of the home and the basement are similar. The difference is temperature which effects the %RH by +2%RH per -1^F temp. 75^F, 50%RH on the mainfloor equates to 70^F, 60%RH in the basement with the same moisture content. From what you discribed, I see no problem with the ducts discribed. What part of the country are located in? Keep us posted on your results. An Aprilaire and Ultra-Aire on the same house, Wow. Regards TB
    Last edited by teddy bear; 07-19-2008 at 08:34 AM. Reason: cleanup copy
    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
    Jul 2008
    Posts
    5
    thank you for your reply. Interesting equation and very useful. I have humidity meter in several locations on both floors and 1st and 2nd floors never get above 45&#37; RH. Only the basement spikes to 60% in summer.

    Basically, if I keep the basement warmer, that will address my basement RH problem, although basement may be excessively warm as a result.

    I am also thinking there is additional moisture in the basement since it is totally submerged and there is probably moisture seepeage from ground and cinder block walls.

    I am located in NJ.

    I preferred UA's fresh air inlet design and also upgraded its filter to Merv11. I'll use Aprilaire for the kitchen area.

    Thanks again.

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