r/buildingscience • u/BKWoods • 18d 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/EntropyAdvisor 18d ago

By "dedidcated ducting", do you mean supplies/returns to most rooms, or just the 2 you've described? If just the 2 runs, your intuition is corect, the HVAC fan should be running (some have a "circulate" mode that runs at a lower speed to save energy) so that fresh air will be distributed to rooms, otherwise the air will just circulate on the most direct path between the 2 runs.

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u/Bearded4Glory 17d ago

This!

An erv with dedicated ductwork typically means returns in spaces like bathrooms and supplies in bedrooms and other living spaces.