While visiting my family up North, I found something that may be an interesting substitute for a radiator. Most Northern homes use floor mounted radiators for heating during the winter. These radiators are essentially a straight run of what appears to be 3/4" Copper tubing/pipe with Aluminum fins mounted in a 3"x3" square configuration. The straight run design of this radiator would mean virtually no pressure drop and, obviously, the design seems to work well in the homes that use them. A simple mod of adding some hose barbs would make these quite usable, though fan mounting may be hard to do. I was thinking that these radiators could be mounted outide, in colder climates of course, and that no fans would be needed in that configuration. If the radiator is placed outside one would need to use antifreeze though to prevent major problems. Anyway, what are your thoughts on this idea?