GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

ERV intake location

BradEL | Posted in General Questions on

In climate zone 3A. We had an ERV installed and were very surprised to find that they installed the outdoor intake and exhaust vents under our screened porch. 

Please see the photo. The fresh air intake vent is the one on the left – kind of in a corner.

Is it recommended that we change this arrangement? Any concerns with this location as far as being under the back porch, kind of in a corner, and above pine straw? Thanks for any insight you can provide.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Michael Maines | | #1

    Brad, it looks like the wall caps are separated by 6' or so, which meets the requirements of most ERV manufacturers. It's certainly not ideal, as that is a spot that will not have the best air quality. If your ERV has a filter fine enough to screen out mold spores, in the MERV 7-9 range or higher, then there is probably no need to move it. Just make sure you clean the filters on schedule. But for the best air quality, the intake should be moved.

    I'm not sure where I found the chart attached but it's a handy guide to filtration levels.

  2. BradEL | | #2

    Thank you, Michael! Is the pine straw creating a problem with air quality there, or is it more the lack of sun and openness? Our options for where else to put it are pretty limited unfortunately. Would half way in between these exhausts (bathroom and gas range) be better for the intake location? I had read not to put it above a paved surface. Thanks so much for your help! The ERV is just the Aprilaire 8100 and we have a Lennox pureair. I’ll have to check MERV for the ERV filter.

  3. Expert Member
    Michael Maines | | #3

    I wouldn't worry about the pine straw; the turpene odor may make it through but to me it's not a bad smell. The problem is the lack of air flow, due to the inside corner and especially to the porch floor above--some of the air you will be taking in is the air that was just exhausted, and corners like that tend to be moldy/mildewy. You definitely don't want the intake anywhere near a gas exhaust. Could you swap the intake and exhaust at the interior?

  4. BradEL | | #4

    Thank you, there is some sort of weird smell coming in, that’s why I wondered about the pine straw. Do you mean the ERV’s exhaust and intake being swapped? Yes, we could swap those but unfortunately that side wall closest to the ERV exhaust has other exhausts (furnace, hot water heater) on it. I think they only put those under the porch because that sidewall wasn’t really an option, and going to the other side of the house would’ve been a lot more work. I’m going to look into the possibility of the other side of the house. Thank you for all your help!

  5. Expert Member
    Michael Maines | | #5

    Brad, yes, I just mean swapping the ERV intake and exhaust, to get the intake closer to fresh air. Another option could be to extend the intake up, like a snorkel, to pull air from above the porch floor. I'm not sure what the ductwork would look like but at least you'd be pulling in better-quality air. If you change to the other side of the house, just check the manufacturer's specs to see what they recommend for duct lengths, as they usually expect the runs to the exterior to be relatively short.

    Be thankful that you don't also have to deal with snow; properly locating ventilation intake in basement-mounted, cold-climate homes can be a challenge.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |