Attic heat project designed from the bottom up

[Exeric]

Originally Posted by Daox

I think I get what is going on here, but where are your fan(s) going?

Daox, it seems appropriate that the first smart cookie to ask it was you. I have thought long and hard about that and have decided the best fan is no fan. I built the ducting to the living space with oversized dimensions and with as minimal a distance as possible just to cut down on air friction. There will probably be less air friction in the duct than there will be in the little filter at the bottom that the air goes through. That means that the only real effective resistance to bringing that air down to the living space will be due to overcoming the stack pressure.

Since this system is bringing warm outside (fresh?) air in winter it makes sense to just use it as makeup air for a bathroom fan. So that's what I plan to do. I think a an 80 or 130 CFM Panasonic bathroom fan should be plenty to overcome the stack pressure and bring that warm air in. The advantage of doing it this way is that you avoid most of the draftiness of only warm, (not hot), air being blown on you from a pwerful fan.

The trick is you have to make the house pretty air tight to do that. Otherwise the house will find some other way than the open duct to get that makep air. I've been spending a LOT of time making the envelope airtight.
I'm also planning on installing a Aldes makeup air vent for those times when I can't, or don't want to, use the attic as a makeup air source.