[AC_Hacker]

One thing to keep in mind is that older ventilation systems assumed that there was enough air leakage in a house to naturally supply fresh air.

And the older ventilation systems supplied NO fresh air and exhausted to the outside NO stale air.

Whenever a non-vented furnace or gas water heater fired up, because inside air was used for combusion air, it created a negative pressure inside the house, which pulls in cold, fresh air.

HRVs are built with a fan to exhaust stale air and an equal-sized fan to bring in fresh air, thus maintaining zero pressurization.

However you hook up your HRV, you will want to maintain the zero pressurization.

You will also want to assure that you have no appliances that use inside air and can create negative pressurization.

This could mean adding an outside air inlet to furnace room, or water-heater closet, or even stove hood power vents.

It could be a lot of hassle, but it will mean that you will have no net positive pressure, which would push out heated air, or net negative pressure which would pull in cold unheated air.