"Fredericton man builds $300 solar furnace, decreases heating bill"

[sendero]

3. Interesting...

... in this article, the guy is using something like a 4" inlet/ outlet pipe. That provides a cross section of 12.5 square inches. The vents in a typical air contitioning or heating system. They are typically 6" an area of 28.26 square inches.

I googled around and found several designs using various sizes of inlet/outlets pipe, including one with a 1.5" pipe, for a cross section of just 1.76 sq in. I'm pretty sure that is not going to work.

I think you would need a big pipe to get enough air through one of these things to do any good. What size pipe did you use?? From the high temp readings it sure sounds like you need bigger pipes!

I plan on building one of these some day!