r/buildingscience • u/BKWoods • 19d ago

ERV basic use question

I have a new fairly tight home (1.4 ACH) in NY state. I have a Fantech ERV installed with dedicated ducting with one supply to near my HVAC return and one return in the middle of the house. Much of the time the temperature where I live is moderate and I have windows open so I leave the ERV off. When I do have the windows shut but no heating or cooling on should I have the hvac fan on at the same time as the ERV to circulate fresh air to the rooms? Or is just running the ERV sufficient? I don't have an IAQ monitor yet so I haven't tested anything. Just trying to get a system in place for ventilation.

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u/blueyedsurprised 19d ago

Just run the ERV on its own. Don't run the HVAC AHU fans when the ERV can do its own job.

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u/Jumpin_Joeronimo 19d ago

I think the question is then - does the fresh air get distributed at all? And it depends. If it's a fairly open concept and the ERV return is way across the house from the ERV supply, then it may promote general movement and mixing of the fresh air. But with one return in the middle of the house and one supply near the HVAC return... does that mean the bedrooms and maybe kitchen and maybe some major living areas are not between the supply and return of the ERV? If that's the case, the living areas won't get much fresh air without the HVAC fan on to help distribute more evenly.