Heat Exchanger Schematic

Im trying to make a heat exchanger for forced air, I need help.?

The unit Im making is brand new, never before seen or even thought about, I need a way to heat air from a controled flame. I need some simple,cheap, and easy to make Schematics so I can build it myself. All plans of the unit are confidential.

The type of system you seem to be talking about is already in use in domestic hot air circulation systems…my home is heated in this way.
But, seems to be that your idea is for a smaller unit.

Another U-shaped solar heat exchanger