I posted last week that we exceeded our expectations regarding house sealing.

I have a few initial questions during our HRV research and wanted some opinions please.

1 - Venting -

Can I vent / supply the HRV as indicated in this DOE image?



I am considering using the soffit vents as a means to vent and supply the HRV .
Please keep in mind that the soffit area is sealed from the interior envelope with spray foam so there will be no roof venting taking place.

2 - Pressurization -
Will an HRV allow air flow even when not running? The reason I am asking is I wanted to make sure i can utilize it even if not running to compensate for the negative pressures in the home created by the dryer or kitchen vent.
Can anyone confirm this?

Thanks for the time and help!
Dave

Most I'm aware our designed not to pass air when turned off, however most are not air tight.

I'd mount the HRV near an exterior wall and run both of the cold ducts to that wall (with 6'+ spacing). Ie, minimize the length of cold (in Winter) duct runs. Best to put the vents at the neutral pressure plane of the house (vertically) and not on the prevailing wind windward or leeward sides.

The HRV that I have, a Venmar EKO 1.5, seals off the duct leading to the outside on the fresh air side, but not on the stale air side, at least that I can see. It is possible that the stale air side is sealed within a closed chamber that I cannot see into.

Ideally a HRV unit should have a damper door setup that would close when the unit cycled off, right at the fresh air intake side.

Is it good to have another similar door on the exhaust side? I would think so. No point in having air leakage on either side when the unit is off.

With sealed soffits, that should work fine for a location. I would put them both on the same side of the house so intake and exhaust are in the same pressure zone. Make sure it is in a easy to reach spot so you can clean the core now and then. My HRV leaks air from both the exhaust and supply vents when the house is depressurized by my range fan (confirmed with blower door). The CFM50 for my house is around 380 with the ERV vents blocked and around 420 without being blocked. If you had a 6” diameter hole in the wall you would get 211 cfm at 50 pa pressure difference, so the HRV has an effective net free area of around 20% ( Fantech 1400 ERV) With the ERV running on High it is around cfm 450 because of differential flow rates from the fans at +/- 50 PA. I have never checked the fan curve tables to see if this make sense, but it is what it is. The net result is that the pressure in your house won’t change much due to a HRV/ERV. It helps a small bit