I'm sure that I will get stomped on for saying this but Geothermal heat pumps are a waste of money in my opinion. For example I can install a complete 15 seer system with ductwork for around $7200 and a geothermal with wells are $18-20,000 installed. The life span on both units are 12-15 years. Also you still have to have electric backup on both units because your heat loss will always be larger than the unit sized for it at a given temperature and once that kicks in everything is basically equal for running cost. Now if you weigh all these things together have you saved anything until maybe the last year or 2 of it's life.