I'm picturing something like this:
Insulated on one side and a flat metal (15"x11" sheet Aluminum?)
on the other side. This solar exchanger looks pretty easy to build..
Need to find out how to bond the copper tube to the sheet metal.
I was also thinking of a welded aluminum tank. 15"x11"x2"
with two 1/2" pipe fittings on one edge. Maybe some sheet metal
baffling inside to make the coolant circulate over all 165 sq inches
of the contact plate.?.
Comments please..