The key piece of the geothermal system is the ground loop. This is made of conventional polyethylene pipe, with thermally fused joints for reliability – most carry 50-year warranties! A fluid, often including a non-toxic antifreeze (propylene glycol), is pumped through this ground loop by a small circulating pump. It is this fluid that transfers the heat to/from the ground and your building. The heat pump unit is connected to the loop and operates as explained above. Heat pumps have become a common piece of mechanical equipment, and are made and sold by many of the heating and cooling companies that supply conventional equipment. (Interested in even more technical detail? Click here.)
The ground loop can come in several different configurations.
Proceed to Closed loop systems