Southernbelle,
My house is mostly glass facing south, and I have seen no problem with this design. There is a minimum of roof overhang, but the sun being low in the sky in winter and high in the summer is what makes all the difference.
tejasrojas is referring (I think) to a wall-pak A/C, not the Slim Jim you mean. That is, I think yu mean the radiator thing that goes in the pond rather than a few thousand feet of plastic tubing. I found that a Slim Jim casts about as much as having the tubing installed. It has to be kept clean or it doesn't work, and I just couldn't justify not going the conventional route. It might be worth doing in a small pond, but you say you will have 3 acres.
I'm heating / cooling over 7000 sq ft with a 6 ton geo system. Humidity is not a problem here in Georgia. Neither are the electric bills which are under $100/mo.
Brettski, a geo installer told you about the defrost cycle? Find a new geo installer.
