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  1. #1
    Join Date
    Jan 2011
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    11

    Basement suite - Dehumidification options?

    We are creating a basement suite in our house. Currently, it is unoccupied and the relative humidity this summer is 70-72%.

    Part of the legal suite requirements say that we must block the forced air ducts to the suite and install separate heating. We've decided on electric fan heaters.

    We want a way to bring down the humidity, especially once the suite is occupied and people are cooking, showering, etc. The suite will have two bathrooms. If we place a dehumidistat in a central location and wire it to both bathroom fans, will this effectively lower humidity?

    The other option is to install a stand-alone dehumidifier (50-70 pint) but we are concerned about noise.

    The suite is approximately 1500 sq ft. What is the best (quietest and most effective) way to reduce humidity?

  2. #2
    Join Date
    Jul 2002
    Location
    Yuma, AZ
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    2,361
    Quote Originally Posted by daytona89 View Post
    ...We want a way to bring down the humidity, especially once the suite is occupied and people are cooking, showering, etc. The suite will have two bathrooms. If we place a dehumidistat in a central location and wire it to both bathroom fans, will this effectively lower humidity? No. Not enough running time.

    The other option is to install a stand-alone dehumidifier (50-70 pint) but we are concerned about noise. Yes. They have decibel ratings (I think). Look for a rating of 35db or less. ....
    Stand-alone.
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  3. #3
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    734
    http://www.thermastor.com/Santa-Fe-Compact/

    This is the model we use for our residential basement finish work. You will need help in sizing a dehumidifier properly.

  4. #4
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Do minisplits have dehmidificaiton functions while in heating mode? that could be an option.

    If your go with a dehumidifier, it might be more effective to duct it to each room if feasible and locate it in a closet.

  5. #5
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    734
    Mini-splits do have a demudification mode, but also cool the air while in the mode. Not an option for basement dehumification as one of the common problems is the cool ambient temperature.

    We operate radiant floors year round in some of our basement finishes here in Minneapolis.

  6. #6
    Join Date
    Jan 2011
    Posts
    11
    Do you mean the whole house units or the ones you can buy that are on wheels?

    Also, I'm still not clear on why the bathroom fan method wouldn't work; wouldn't the dehumidistat keep the fans running as long as necessary? That way we could get very quiet (e.g. panasonic) bathroom fans, and use those.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,096
    Quote Originally Posted by daytona89 View Post
    Do you mean the whole house units or the ones you can buy that are on wheels?

    Also, I'm still not clear on why the bathroom fan method wouldn't work; wouldn't the dehumidistat keep the fans running as long as necessary? That way we could get very quiet (e.g. panasonic) bathroom fans, and use those.
    They will cause high humidity outside air to be drawn into the suite. So you won't get the humidity down.

    You'll probably need an A/C also, since cooking will raise the temp in the suite. Along with the people and other appliances.
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  8. #8
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Where is the replacement air coming from?
    Where are you located? (climate issue.)
    What is the temperature and RH outside?
    Your plan would have a chance in Flagstaff, Arizona.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  9. #9
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    Is this because you only have 2 seasons in MN

    Quote Originally Posted by BadgerBoiler MN View Post
    Mini-splits do have a demudification mode, but also cool the air while in the mode. Not an option for basement dehumification as one of the common problems is the cool ambient temperature.

    We operate radiant floors year round in some of our basement finishes here in Minneapolis.
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  10. #10
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    734
    I installed an ERV which brings in fresh air and "exchanges" humidity. Good ventilation is a must but you will likely need a dehumifier as well. The "wheeled" variety are low performance and usually short lived.

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,444
    Quote Originally Posted by daytona89 View Post
    We are creating a basement suite in our house. Currently, it is unoccupied and the and wire it to both bathroom fans, will this effectively lower humidity?

    The other option is to install a stand-alone dehumidifier (50-70 pint) but we are concerned about noise.

    The suite is approximately 1500 sq ft. What is the best (quietest and most effective) way to reduce humidity?
    Get Ultra-Aire 90H whole house ducted dehumidifier which can be located in a utility area with the dry air ducted to key areas. The unit is very quiet and will keep the basement dry <50%RH. I assume you live in a green grass climate.
    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"

  12. #12
    Join Date
    Jan 2011
    Posts
    11
    Yes, we are in Vancouver, BC (coastal region, temperate, lots of rain).

    There are not a lot of places to put a whole-house unit; legal suite requirements mean that the furnace room has to be separated from the suite area by a sealed self-closing fire rated door. They will not allow ducts to go between it and the suite. That means there's no good place for a dehumidifier to go, since closet space is also at a premium.

    Would a whole-house unit be quieter, louder, or the same as a 70 pint unit on wheels?

    We have a heat pump for upstairs, but given that the RH downstairs in the unoccupied suite is 70-72, it is struggling to maintain 50 upstairs as well. I can't see AC being needed downstairs as it is very cool down there even on the hottest summer days.

  13. #13
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,444
    Quote Originally Posted by daytona89 View Post
    Yes, we are in Vancouver, BC (coastal region, temperate, lots of rain).

    There are not a lot of places to put a whole-house unit; legal suite requirements mean that the furnace room has to be separated from the suite area by a sealed self-closing fire rated door. They will not allow ducts to go between it and the suite. That means there's no good place for a dehumidifier to go, since closet space is also at a premium.

    Would a whole-house unit be quieter, louder, or the same as a 70 pint unit on wheels?

    We have a heat pump for upstairs, but given that the RH downstairs in the unoccupied suite is 70-72, it is struggling to maintain 50 upstairs as well. I can't see AC being needed downstairs as it is very cool down there even on the hottest summer days.
    Codes do allow ducts to the occupied space provided that they have fire dampers. Check with you heating contractor. These unit are somewhat quieter than the residential dehus.
    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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