A ground-source heat pump (sometimes called a “geothermal heat pump”) provides space conditioning by moving heat energy. A ground-source heat pump (GSHP) system can provide heating, cooling and humidity control. A GSHP system may provide water heating, either to supplement or replace conventional water heaters.
Every GSHP system has three major subsystems or parts: a geothermal heat pump to move heat between the building and the fluid in the earth connection, an earth connection for transferring heat between its fluid and the earth, and a distribution subsystem for delivering heating or cooling to the building.
In heating mode, heat is extracted from the fluid in the earth connection by the geothermal heat pump and distributed to the home or building — typically through a system of air ducts. Cooler air from the building is returned to the geothermal heat pump, where it cools the fluid flowing to the earth connection. The fluid is then re-warmed as it flows through the earth connection.
In cooling mode, the process is reversed. The relatively cool fluid from the earth connection absorbs heat from the building and transfers it to the ground.
Above Information Courtesy Of Oregon Department Of Energy – Geothermal Energy
Here is the current list provided by the State of Oregon for companies employing 2014 GSHP/Geothermal Tax Credit Approved Technicians.