I guess that is reasonable, as long as it isn't damp air.
Is that other people's experience? That taking cubic feet of airspace to been cooled, multiplying by the fan's CFM, times a fudge factor of 2-3, would give you about how long it takes to exchange out the air in the airspace?
I just need to exchange the air on about 4800 cubic feet. Not to have the fan strong enough to set up a breeze you can feel.
If I were exchanging the air 2-3 times/hour as you suggest, that would be a 240 CFM fan. If I were only exchanging air every 2-3 hours that would be a 40 CFM fan.
One person said, they need a 6000 cfm fan. But they have a masonry house which must have a giant heat capacity. I have a wood frame house. I have a total of about 1000 sq in of exhaust and intake ventilation in my attic.
Running a fan for just a short time wouldn't work, because on really hot days in the summer, the low of 70 F isn't reached until the early morning hours.
Ideally what would be great would be a variable speed control AND a thermostat, so the fan would shut off if the inside temp gets down to
65 F ...Fantech's variable speed controls go from 0-100%. Does anyone know if a speed control will work fine at, say 10-20%?
Thanks for all the answers!
Laura