[redpoint5]

Originally Posted by freebeard

I now have a b-day present on the way, a six-pack of discountfilterstore.com/[14x14x1 Merv 11 Universal Air Filter By Tier1 (6-Pack)]. I will need to put a slide cassette between the whole-house fan and reverse it's flow (AC motor's orientation in the bracket). Voila! Overpressure.

What's this overpressure concept? Is it like positive-pressure?

You can't maintain the purity of your indoor air as long as it depends on the outside air as an input, and you especially cannot filter out viruses.