This is what I would like to do.
Build a box 4' X 8' with with copper tubing and glass for the collector on the roof coming into the shop with 3/8" tube coiled around a 30 gal water tank to heat the tank.
Using the water in the tank to heat the shop going threw 2 heat exchangers with fans behind each.
Both will have a thermostat, one on the roof to shut off the pump when temp. gets low and the other in the shop to regulate the shop temp.
The shop is 24' X 40' the temp. here gets a low of about 30 degrees (in Tn.)
What I need to know is will this work?
Pump GPM?
Size of collector?
Size of shop heat exchangers to heat shop?

Thanks for any help
Semon