Thanks Iamgeo. Even with the limited amount of success I've had here I'm still not convinced that an attic solar system will do well in all climates represented on this forum. I think it will probably work and save considerable amounts of energy in places like California, Texas, and most states south of the Mason-Dixon line. But the Pacific Northwest and Alaska... forget about it. In the former there is just too much cloud cover and the latter the sun is just too low in the sky. I think in selective areas north of the Mason-Dixon line it might eventually be a useful way to help heat your house. I think the jury is out. I think you would have to forget about using a direct heating system from the attic in most of those places and just use it as a tie in to a basement, crawlspace, or as a fresh air input to a forced air heating system.