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Community and Q&A

Basement ventilation system

bridorf | Posted in General Questions on


Finishing a basement area for habitation in Seattle (marine climate) and was planning on installing some type of air exchange system since the basement won’t be connected to the forced air system for the rest of the house.  Point exhaust present in bathroom already.

I was leaning towards a basic Air Exchange Venting system like the AEV 80 made by Fantech, but this has no recovery system present.  

I realize that only a dehumidifier can truly dehumidify the air, but am wondering about the pros/cons of installing an ERV vs. HRV for a continuously operating system instead to not pull heat out during the winter. 

I have found that things tend be more humid outdoor/indoor during the summer here and would like to minimize or at least control the humidity in the basement during the summer as well as provide air exchange potential.  I was leaning towards an ERV. 

Less of a question than a request for expert advice & knowledgeable opinions.

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  1. Expert Member
    Michael Maines | | #1

    If indoor RH is high in the summer and you have a dehumidifier (or air conditioner), an ERV is a better choice because it doesn't bring in as much moisture from outdoors. In situations where wintertime RH is a bigger issue, then an HRV is a better choice because it brings in dry outdoor air.

    1. bridorf | | #3

      Thanks. Primarily I was looking for something to provide air exchange, but thought it wise to have some sort of heat recovery so as not to waste heat supply during the colder months. Given that a basement tends to be more humid I wasn't sure what would be best HRV, ERV or just an Air Exchange ventilator. Planning to run it continuously.

  2. Deleted | | #2


  3. DC_Contrarian_ | | #4

    Ventilating the basement in the summer will make it more humid. In the summer you want to seal it up and dehumidify it.

    1. Expert Member
      Akos | | #5

      +1 On dehumidifying. Around me (Zone 5) most finished basements always have a stand alone dehumidifier. Turn it on in the spring and turn it off in the fall.

      If there is a bathroom there, for ventilation I would install a Panasonic spot ERV unit instead of standard bath fan. The cost of one of these is only a bit more than a quality exhaust fan and you get some (not great but much better than zero) energy recovery.

      Set it to run on low all the time and use a motion sensor to kick it into boost when the bathroom is in use.

      Even if there is no bathroom, you can mount the spot ERV in the ceiling somewhere.

      Also, if you are in radon land, having continuous ventilation in the basement can make a big difference in radiation levels.

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