Geothermal HVAC Systems

Geothermal HVAC Systems are among the most energy efficient systems available, with energy savings up to 70%. They also have the lowest life cycle cost of any HVAC system. While these systems cost more to install initially, they require less maintenance than regular HVAC systems.

The basic geothermal HVAC system consists of three main parts. The first part is the reversible refrigerant loop, which is either an open or a closed loop system. With an open loop, water is pumped from a well back into the system and returned to another well or discharged onto the surface. This is called the "pump-n-dump" method and not very common. The closed loop system is industry standard. With this system water is used over and over again, instead of dumped out. Closed loop systems are installed in one of three ways: horizontally, vertically, or submerged in a pond or lake.

Horizontally: a series of plastic pipes are buried in trenches four feet deep. This method is economical where sufficient land is available.

Vertically: pipes are buried in a series of holes drilled twenty feet deep. The holes are then filled with grout, which ensures good heat transfer between the pipes and the ground. This method is more expensive to install, but less land is required, which makes is more common in large cities and towns.

The final method is installing a loop system in a pond or a lake.

The second part of Geothermal HVAC systems is the heat pump. This pump works like a typical air course heat pump, except without equipment outside the home. The heat pump uses a reversing valve to change the direction of the refrigerant flow, which determines whether heat is added or removed from the air. It can also provide hot water by adding a desuperheater, which is combined with a regular electric water heater.

The final part is the duct system, which is similar to a conventional duct system, only bigger.

(source: http://www.igshpa.okstate.edu)