[HayZee518]

geo thermal temperatures range from 54 to 57 6 feet down in the ground. a closed system of ethylene glycol is pumped through the system to absorb ground heat or discharge heat to/from the ground. the glycol goes through another heat exchanger to pick up/discharge heat from a closed loop freon system. next the air is blown into the dwelling. if the temperature is below nominal an auxillary heater is started up ahead of the heat exchanger for heat and uses machine fan to blow the heat into the house. for costs you have to consider amount of heat/air exchanges per hour for a given temperature variation say 68-72 degrees. what you can absorb from the ground in a 24 hr period. electricity used for the glycol pump, compressor, air handling. next is cost of freon and which type R-12, R-22 or R-134a.