Geothermal (ground source) heating systems are a very rapidly growing technology in the residential / commercial heating and cooling market. Even though it does cost a little bit more in the beginning to install rather than traditional HVAC system it repays itself quickly because of its low maintenance cost.
Geothermal system usually consists of heat pump and ground heat exchanger. Heat exchanger is a buried loop field of pipes, slinky or horizontal or one or several vertical bore holes which makes the heat transfer to or from the ground (on the depth below 7 feet ground temperature stays the same around the year in New England and Tri-state area). The systems with buried pipes are called closed loop systems because the coolant circulates within the closed loop as oppose to the open loop systems where wells or ponds are used to exchange the heat. While choosing between horizontal slinky and vertical boreholes various factors should be taken to the account: systems with horizontal loop field are usually easier to install but they require more available land and have longer pipe run. The open loop systems are usually a bit chipper than closed loop as well and they require smaller heat pipes but they require very deep wells, so more money is spent on drilling, they have more difficult and time consuming installations, and there might be possible environmental complications that are related to the bleeding off the well.
Another very important part of a geothermal heating system is a heat pump, which is in the way just large refrigeration unit that can work both ways moving heat to or from the ground depending on the cycle it works in. The most commonly used unit in geothermal systems is the ground-to-air heat pump. The unit includes a heat exchanger, refrigerant piping and control valve, compressor, air coil, fan and control switchboard.