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  1. #1
    Join Date
    Oct 2018
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    Whole home Dehumidifier

    Hello, I have a question that regarding building a new home in Northern Wisconsin...
    Would a whole home dehumidifier be a better solution for "cooling" a home vs. AC?
    We average about 7 to 12 days of above what I would consider higher dew points and humidity per year. I'm quite comfortable at 76 degrees and 42% humidity in my home vs. 72 with AC and relative humidity of 37% or so, thoughts?

    I understand resale value with AC.

    Looking for an effective alternative to AC for those few days of the year.

    Thank you in advance.

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    I suggest a minimum of mini-split high in the open part of the home wood do me.
    If you have a developed basement with a rec area, a whole house dehumdifier with fresh air ventilation for the mild part of year when natural infiltration is minimal would fit well.
    Drawing air from the main flow to the dehumidifier with main dehumidifier supply to the basement will cause dry eool basement air to circulated throughout the home. A typical basement in the WI climate is good for a ton of cooling to the home. This require a vent on the basement door or a VS furnace blow recirculating 24/7.
    Your home will <50%RH which is worth 3-5^F of cooling. 78^F, <50%RH is acceptable. Add a mini split of 1.5 ton to the furnace.
    Keep us posted.
    Regards Teddy Bear
    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
    Jan 2004
    Location
    PA
    Posts
    75,874
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    Moved to AOP.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
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    HOUSE WITHOUT BASEMENT

    A Whole House dehumidifier is Not really necessary
    for a region with < 800 Cooling Degree Days
    And Design Day Dew Point < 71'F

    _ Set up a 14 SEER A/C appropriate for the region.

    Wausau ___
    _______ _ Dry Bulb / Wet Bulb
    ASHRAE 1% _ 84.5'F / 69.5'F

    _____ 7,973 Heating Degree Days
    _____ 462 Cooling Degree Days

    A/C operating hours ought to be < 370 per year.

    https://www.energycodes.gov/sites/de...quirements.pdf
    Building THERMAL ENVELOPE should be built to
    2015 IECC
    as a minimum criteria.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Dan, what you do not realize is that green grass climates with fresh water lakes have extreme high dew points. The Midwest has some of the highest dew point in the word. Sept. this year Madison wi was as high as Miami.
    Also some homes owners extpect humidity control much like you want temperature control. High humidity for weeks is more damaging than high temperature and also uncomfortable.
    Rainy weather and fresh water generate high dew points. Homes with basement/crawlspaces are sensitive to high indoor dew points.

    Without extended hours each day of sensible cooling a properly setup a/c is unable to remove more the moisture from fresh air infiltration/ventilation plus the moisture from the occupants during days/weeks of low sensible cooling loads in green grass climates.

    Name:  Record dew points.jpg
Views: 60
Size:  102.8 KB

    Regards Teddy Bear
    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"

  6. #6
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    8,503
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    I have to adhere to the Building Codes / ASHRAE in developing HVAC designs.

    Otherwise at times, I may be liable,
    be labeled an engineering outlaw
    And CONVICTED of Malpractice, Negligence or other.

    ---
    Point given [post # 5] exceeding the ASHRAE criteria is
    Very Short term
    and well within the 1% criteria / 88 hours Annual Duration.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    8,727
    Post Likes
    Quote Originally Posted by dan sw fl View Post
    I have to adhere to the Building Codes / ASHRAE in developing HVAC designs.

    Otherwise at times, I may be liable,
    be labeled an engineering outlaw
    And CONVICTED of Malpractice, Negligence or other.

    ---
    Point given [post # 5] exceeding the ASHRAE criteria is
    Very Short term
    and well within the 1% criteria / 88 hours Annual Duration.
    If the a/c is designed according to ACCA and the home meets the local codes, there will be no problem with high indoor moisture levels during times of low/no sensible cooling loads and high outdoor dew points. So during days of rainy weather systems and moisture from design levels of occupancy with comfort, mold and dust mite problems. Great, we will consider your butt covered.

    I talked to the designer of Manual J a couple weeks ago and raised the issue. He said that in green grass climates, do not expect the a/c to handle latent loads design day evenings and rainy days.
    Go figure. Any volunteers for temperture/%RH monitoring on evenings and rainy days showing 50%RH provide with an a/c, evenings and during rainy weather? Even a good technical explanation would help.
    Thanks for your comments.
    Regards Teddy Bear
    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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