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  1. #1
    Join Date
    Oct 2007
    Posts
    9

    Question Radiant Heated Basement needs Dehumifier

    Any advice for me...
    I have a basement that is fully heated (in floor hot water radiant heat) some of which is liveable space (rec room and full bathroom) -- no ductwork.
    Need to dehumidify. Any suggestions?

  2. #2
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Quote Originally Posted by Dayna View Post
    Any advice for me...
    I have a basement that is fully heated (in floor hot water radiant heat) some of which is liveable space (rec room and full bathroom) -- no ductwork.
    Need to dehumidify. Any suggestions?
    Thermastor has made an excellent line of dehumidifiers for some time now, I believe basements were one of the original applications. What makes them better is high pints/day capacity combined with a low energy use. They are well designed and built, however they are not all that cheap.

    I live in a hot-humid environment where we need the dehu function mainly in spring and fall when AC is not running yet air is humid. My chosen dehu is a Thermastor Santa Fe RX and it works well for me. Often I recommend people might buy a cheaper 40 pint/day dehu (which consumes nearly the same electricity BTW) just to test out the concept in their house. Then with a little experience you can judge whether you want to get the Cadillac of dehus.

    I am not a professional in this are but the only one I know of, is Teddy Bear who works for the above company. I have almost never seen him to give bad advice though, you can believe what he says.

    Hope this helps -- Pstu

  3. #3
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725

    Just curious.

    What is the temperature in this humid basement?

    MA

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by Dayna View Post
    Any advice for me...
    I have a basement that is fully heated (in floor hot water radiant heat) some of which is liveable space (rec room and full bathroom) -- no ductwork.
    Need to dehumidify. Any suggestions?
    Thanks for the kind previous post. Assume you live in a cold green grass climate. Size of home and location would help. Usually a 90 pints/day dehumidifier will maintain <50%RH in upto 2,500 sqft. basement. The Santa Fe Advance can be ducted throughout a developed basement. You may wish to incorporate the rest of the home in your humidity control. A little fresh air to purge indoor pollutants and renew oxygen during stagnet summer weather may be desired. Check thermastor.com for options. Regards, Dehu 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"

  5. #5
    Join Date
    Oct 2007
    Posts
    9

    Thanks for advice so far... More info of situation.

    My basement, like I said is heated by radiant in-floor hot water heat. Of course we only have the heat on during the winter and keep it at about 68F.
    The basement is about 1200 sq ft of which almost 800 is "livable". The only fresh air we have is what is naturally exchanged from the stairway (which is open to the up stairs/main level, two egress windows (4'x4') in the rec area, and there is a bathroom exhaust vent.
    I live in Wisconsin. The humdity is less when the heat is on, but still we run a portable dehumidifier which sits in the middle of the room.
    When we run the air conditioning upstairs it doesn't effect the basement much, except you can feel the cold fall by the stairs... however, the basement, since it is not at all exposed, maintains a nice cool temperature in the summer on its own.

    I will check into the Thermastor, however, until then, any further information or advice?

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Cold climate homes breathe better during cold weather. If your windows do not sweat during cold weather, you will be ok until next spring. Monitor the %RH in your basement. Keep the basement <50%RH next spring-fall. If unable get a biger dehu. Regards Dehu 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"

  7. #7
    Join Date
    Oct 2007
    Posts
    9
    I maintain in livable area of basement of about 45%RH with the portable dehumidifier. Probably could maintain it throughout the basement if I ran several portables.
    Problems I dislike about the portable is that for greatest efficiency I must keep it in the middle of the room. To drain I must either run a hose from it to utility room or physicially dump every so often. Plus it is noisy.

  8. #8
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725

    Radiant floors in basements...

    can be left on to keep the slab warm and dry driving the rh down in the process. This can be done if the basement is say 66F and you set your thermostat to 68F.

    When the cold dry air from above meets the warm floor you have comfort.

    Many of my customers run their basement floor year round with great effect. Dehumidifiers extract moisture (using expensive electricity) and create a lot of waste heat with has the same effect as heating the floor without the more even comfort.

    MA

  9. #9
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by BadgerBoiler MN View Post
    can be left on to keep the slab warm and dry driving the rh down in the process. This can be done if the basement is say 66F and you set your thermostat to 68F.

    When the cold dry air from above meets the warm floor you have comfort.

    Many of my customers run their basement floor year round with great effect. Dehumidifiers extract moisture (using expensive electricity) and create a lot of waste heat with has the same effect as heating the floor without the more even comfort.

    MA
    What %RH will we get with the basement temperature set at 68^F? With the outdoor dew point at 70^F while raining, the indoor dew point reaches 60-65^F. All surfaces inside the basement below 68^F will sweat. This includes water pipes and exterior masonary walls behind insulation. Yes, the floor under the carpet is ok with a warm slab. How much of that "cheap" gas does it take to keep the floor warm and not protect anything eles? High efficiency dehumidifiers use 1 KW to remove 4-7 lbs. of moisture and add 7,000-10,000 btus of heat. Typically, removing 30-50 lbs. of moisture per day uses <10 kw per day to maintain <50%RH throughout a 2,000 sqft. basement. At $.10/KW, <$30 per month is used to raise the temperature 4-5^F while lowering the dew point 15-20^F. The effect is a very comfortable basement at 72^, 50%RH. The dew point of the air is lowered to <50^F, eliminating condensation on all plumbing pipes and cool masonary surfaces. These high eff. dehus generate 70,000-100,000 btus heat for $1 (COP of 3). The Santa Fe type dehus can be remoted in an utility area and ducted to finished spaces. Typical residential dehumidifiers are more expensive to operate and removes less moisture. I like warm floors during cold weather but they are nothing like a high eff. dehu. Regards, Dehu 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"

  10. #10
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725

    Turn the heat on in the basement.

    OK, turn the basement thermostat to "a very comfortable radiant 72F.
    The cost per BTU will be a 1/3 of your 10 cent a Kw demudification.

    I'm not saying dehumification doesn't work or that it isn't necessary in some applications, but I would heat the floor first, like reheating chilled air in a commercial system.

    Why is the basement damp to start with?

    MA

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by BadgerBoiler MN View Post
    OK, turn the basement thermostat to "a very comfortable radiant 72F.
    The cost per BTU will be a 1/3 of your 10 cent a Kw demudification.

    I'm not saying dehumification doesn't work or that it isn't necessary in some applications, but I would heat the floor first, like reheating chilled air in a commercial system.

    Why is the basement damp to start with?

    MA
    In green grass climates, moisture loaded air infiltrates the home. If not, you should ventilate 7.5 cfm/person plus .01 cfm per sqft of home. The outside air contains moisture. Add the moisture generated by occupants, the moisture that diffuses through the walls and you have +50 pint per day dehumidification load. If not addressed, you will end up with a damp house during high dew point weather.
    You missed the 70-100,00 btus of heat generated by a high eff. dehu using $1 worth of electricity. In addition 40 lbs. of moisture is removed from the air in the basement. How much heat is added to the space a $1 worth of nat. gas with slab heat. Less heat from $1 nat. gas is delivered to the air without any reduction in the moisture in the air. These high eff. dehus are high cop heat pumps. Keeping a basement dry also helps reduce the %RH throughout the home. Give us some numbers on gas consumption to maintain 72^F along with resulting %RH in the space. Will this keep water pipes and insulated walls from sweating? Regards Dehu 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
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725
    You got me there Teddy Bear.

    Hehehehee

  13. #13
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Thanks I am a fan of warm floors and dehumidifiers. 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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