I can't help much with the Geo. Dwight lives in Minnesota and has a geo system, and it seems to keep his house warm without running on any aux heat. Hopefully he will chime in.
I would search far and wide for a company that will do an energy audit on your house. That's where they put a temporary door in, with a fan. They turn on the fan to suck air out of the house, and they then check to see where air is coming in. They then go around plugging all the holes to get the house more air tight.
I'm going to have that done to my house this summer. First thing that they'll have to do is spray foam the crawlspace. Then we'll see where all the outside air is coming from. I've blown in insulation in the walls and ceiling, installed all new windows, ripped all the siding off of the house (except for the first layer - no sheathing on the house) and re-sheathed it, caulked the seams and tyvek wrapped it. I still have considerable amount of air flowing through the house.....
Welcome to the forum!!
