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Would it be better to have a HRV/ERV and no exhaust fans from the house or have

Post in 'The Green Room' started by Midalake, Feb 2, 2011.

  1. Midalake

    Midalake Member

    Joined:
    Aug 22, 2010
    Messages:
    35
    Loc:
    UP of MI
    exhaust fans from the house and no HRV/ERV. I will be building and I think this is a topic that really needs to be addressed. It will not matter code wise where I live.

    Dave

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  2. nate379

    nate379 Guest

    Not sure what you mean by "exhaust fans from the house and no HRV/ERV"
  3. semipro

    semipro Minister of Fire

    Joined:
    Jan 12, 2009
    Messages:
    2,389
    Loc:
    SW Virginia
    I've always thought that exhaust fans whether bathroom, kitchen hood, clothes dryer are a waste of conditioned air. I've always wondered if routing those so that they pass through an ERV before exiting the house would recover some of the invested energy and control the quality of make-up air. I'm not sure the impact of the moisture on the ERV though and of course you wouldn't want to route heated air (dryer) through the ERV during the hot season.
  4. WhitePine

    WhitePine Feeling the Heat

    Joined:
    Sep 18, 2010
    Messages:
    497
    I don't think an ERV could handle the humidity load from a bathroom fan, and I'm sure it couldn't handle a dryer's.

    What would be a good idea it to put the ERV/HRV's inside air intake near the cats' litter box. I just wish I had thought of it before we built the house. :sick:
  5. Alan Gage

    Alan Gage Member

    Joined:
    Oct 8, 2008
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    Loc:
    NW Iowa
    I'll be building a small (roughly 800 sq. ft) house this spring that will be well insulated and sealed tight (I hope) so this is something I've started looking into. When I first read about HRVs I was put off because of the cost and it seemed a bit overkill. If I didn't come home for a week it would just keep running. I don't have AC either and keep my windows open whenever I can. No need for an HRV then.

    Then I heard about the exhaust only passive system and I liked the sound of it much better. Basically you supply a couple fresh air intakes in the house and rely on your bathroom and kitchen vent fans to do the air exchanging. Put them on a timer so they run a predetermined amount of time. If you're home you'll be using the vents as you cook or use the bathroom and if you're not home there's no wasted energy in exchanging the air in the house. I've heard of a couple people using the wood stove as one of the main air exchangers instead of installing an OAK. The vent fans make up for it in the shoulder season and in warmer weather you'll have the windows open (assuming no AC).

    Some reads I've come across for anyone interested:

    http://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/exhaust-only-ventilation-systems

    http://www.greenbuildingadvisor.com/blogs/dept/musings/designing-good-ventilation-system

    http://forums.jlconline.com/forums/showthread.php?t=45305

    What's really right I don't know, they probably all are if done correctly.

    Alan
  6. nate379

    nate379 Guest

    That is what I have in my house. It's a cheap way of getting required air exchanges (for building code) in a house without having an HRV.

    The bath fans are setup on adjustable humidistats so when humidity gets too high the fan(s) will run. Also something else I did was put the fan switch on a timer that stays on for 20 mins after turning it off. Fan would get left on most of the day sometimes cause someone would want to clear the stink and then forget about it. The fans are so quiet you can't hardly tell they are on even in the bathroom.

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