Passive Solar question

[gmparker2000]

I built a small window soda can heater a few years ago that mounted to the inside of one of our south facing front windows. It worked fairly well but it wasn't large enough to make much difference. I am currently thinking about building a much larger panel behind the house (no good place to mount on the front of the house). It would sit on the back porch during the winter months far enough back to get out of the shadow of the house. However, this would mean that I would have to pipe air to and from the panel, a distance between 12 to 15 feet. I was thinking about using 2" PVC pipe. Firstly I'm wondering if PVC is a good idea for a heating system? Is it possible that temperatures would get warm enough to cause problems? Secondly, I'm guessing that I'm going to loose lots of heat through the ~12 feet of pipe unless I insulate it somehow. What would be the best way to insulate something like this? Lastly, I would ideally like to move air from the basement up to the porch, through the panel, and then back down to the basement. If I put an inline fan of some sort in the outlet pipe in the basement would this be enough to pull air down after its heated?

[russ]

Try looking here http://www.builditsolar.com/Projects....htm#ActiveAir

Many projects shown - just use caution as the system shown may or may not work as the builder claims.

A 2" pipe is no doubt too small - PVC should be fine for the temps you will reach

[J.P.M.]

Try looking here http://www.builditsolar.com/Projects....htm#ActiveAir

Many projects shown - just use caution as the system shown may or may not work as the builder claims.

A 2" pipe is no doubt too small - PVC should be fine for the temps you will reach

FWIW, I'd agree that 2" is too small. But because it is too small and somewhat long, depending on the size/design of the collector, the ducting induced pressure drop may lower the flow rate -- >> increase the collector outlet temp. above about +140 F. or so and maybe/probably start to cause problems w/ the PVC, at least at the collector outlet. Not to be discouraging, but this sounds more fruitful as a learning experience than effective heating equipment.

[inetdog]

And just for reference, putting a solar thermal panel inside a window cannot theoretically produce more heat than you would get just by letting the light from the window strike a perfectly absorbing barrel of water. Assuming a perfectly insulated window, of course.
To do well, you have to get your collector outside the room.