[jyl]

My house is three levels (ground 1000 sf, second 1000 sf, finished attic 500 sf) with a full basement (1000 sf). It has a central AC/heat system, which makes the basement chilly, the ground floor comfortable, does little on the second floor, and the attic is roasting on hot days. The ducts to the second floor and attic just aren’t big enough, and there’s no room for larger ducts. The basement is chilly because of all the exposed AC ducts and because it’s the basement.

I’d like to solve this problem.

One way would be to install mini-splits, but I’d need a bunch of them - four bedrooms on the second floor, people aren’t going to want to sleep with their bedroom doors open, plus attic.

So I thought of something. Suppose I run a 10x10 duct from the basement to the attic, on the outside of the house, with a 500 cfm inline fan, to move cold air from basement to attic. Long duct run so maybe I only get 250 cfm. In 40 minutes it’ll move 10,000 cf which is the volume of the basement. The cold air will sink from attic to second floor to ground floor to basement. I could put it on a timer. In the winter, I could reverse the flow.

What do you all think?