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Thread: HRV vs ERV

  1. #1

    Confused HRV vs ERV

    I need some help deciding on ventilation for my basement ~1700sq feet.

    I do have moisture problem in the basement (no leaks) that contributes to the musty smell, which is bothersome. I wold like to use the space and finish the basement. I should also mentioned is that basement does not have air return with central HVAC, the exhausts are present though.

    I do plan to waterproof in the next few years, but for now I think good ventilation system might help.

    the house is in Cleveland, Ohio

    I need help deciding whether I need to use HRV or ERV unit, and the size of the unit.
    Also my thinking is to have separate ventilation system for the basement and not the one tied into central HVAC.

    Please advise

  2. #2
    Join Date
    Dec 2008
    Location
    Ontario Canada
    Posts
    552
    See the link below

    http://www.venmar.ca/en/faqs.aspx

    they have some good resources for home owners when re-searching HRV/ERVs

    if you have a leaky or moist basement, the first thing I think of is an old house, old windows, doors and no vapor barrier. If thats the case, you typically wouldn't be a candidate for either an HRV or ERV. these are typically only recommended in a home built or retrofitted with “tight” construction techniques and a continuos vapor barrier.

    neither HRVs or ERVs actively remove or add moisture to your house, all they do is exhaust building air outside, and bring in fresh air, the only catch is that it runs both through a heat exchanger to recover some of your heat back (HRV) or some of your moisture (ERV) back to make them more efficient than opening a window.

    I guess how leaky is your basement? running mechanical ventilation in the winter will bring in nice and dry air that my help dry things out a bit, but could running your home fan all winter long help bring some of the humidity up stairs where you want it?

    running mechanical ventilation in the summer likely wont help our your moisture problem much (unless it is really bad), as outdoor air is quite humid, do you have AC? could you get an AC tech in to check over the system, tell him you want it do de-humidify the air as much as possible, he could make some system adjustments to do so

    maybe some basement fans and a de-humidifier is all you need?

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,637
    Quote Originally Posted by vl6021 View Post
    I need some help deciding on ventilation for my basement ~1700sq feet.

    I do have moisture problem in the basement (no leaks) that contributes to the musty smell, which is bothersome. I wold like to use the space and finish the basement. I should also mentioned is that basement does not have air return with central HVAC, the exhausts are present though.

    I do plan to waterproof in the next few years, but for now I think good ventilation system might help.

    the house is in Cleveland, Ohio

    I need help deciding whether I need to use HRV or ERV unit, and the size of the unit.
    Also my thinking is to have separate ventilation system for the basement and not the one tied into central HVAC.

    Please advise
    LKJoel has the concept right. You have a wet, damp, cool basement that is growing mold. The moisture is infiltrating from outside and a small amount from the masonary parts of your home to the basement space. More outside high dew point air means more moisture in the basement. Cool basement structures lower the temperature of the air and elevate the %RH to the point were mold grows. What is needed is a good dehumidifier that lowers the moisture in the air. A small amount of heat is also part of the drying process which warms the basemnet 3-4^F which also lowers the %RH. Check out the Ultra-Aire/Santa Fe/Honeywell dehumidifiers for a simple practical solution to the problem.
    When the outdoor dew points decline to less than 50^F, outside will make the space dry. As you see the moisture problems go away when the outside air is dry during cold weather. Most homes will benefit from basement dehumdification throughout the summer months. I suggest that you use basement dehumidification in your home when ever the windows are closed and the home is damp.
    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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