The Ground Source Heat Pump is a machine that removes heat from the ground or from groundwater to provide space and/or water heating.
All Ground Source Heat Pumps have two parts: a circuit of underground piping outside the house, and a heat pump unit inside the house.  The piping circuit can be what is called Open or Closed Loop, and there are two variations of the Closed Loop: vertical and horizontal (which refers only to the way the underground piping is arranged).  Regardless of the type of Ground Source Heat Pump, it can be seen that a major reason for their superior efficiency is because they extract the heat from a source that is free and has a relatively constant temperature—the Earth itself! (Or a body of water; a similar source of natural heat).  The choice of Open or Closed Loop for a particular building depends on the amount of land available, the soil conditions for drilling and the presence of underground water.

Closed Loop Systems:
Closed Loop Systems collect heat from the ground by means of continuous piping Loop buried under the ground outside the house.  A water/antifreeze (glycol) mixture which has been chilled by the heat pump’s refrigeration system to several degrees colder than the outside soil circulate through the piping, absorbing heat from the surrounding soil.

Vertical:
A vertical closed loop arrangement is an appropriate choice for most suburban homes, given the usual size of these lots. Piping is inserted into holes 150mm in diameter (six inches)  to a depth of 18-60 meters (60 to 200 feet) depending on soil conditions and the size of the system.  Generally, about 90 meters (300 feet) of piping is required for each ton (3.5kW) of heat pump capacity.  For example, a 4-ton heat pump unit would require about 365 meters (1200 feet) of piping, which could be accommodated by drilling five 36.5 m (120 feet) holes (each hole takes a double length of pipe U-shaped at the bottom to make a continuous loop. (See Fig.1).

Horizontal:
A horizontal arrangement is found in more rural locations where properties are larger.  The piping circuit is laid out horizontally and the trench is one-two meters deep (3-6 feet), so the expense of the drilling is avoided.  About 120 meters (400 feet) of piping is required for each ton of GSHP capacity. (See Fig.2A). (Note: the horizontal piping arrangement can also be laid out along the bed of a large pond, river or lake. (See Fig. 2B).

Open Loop Systems:
An open loops system takes advantage of the heat retained in an underground body of water.  The water is drawn up through a well directly to the GSHP’s heat exchanger, where it’s heat is extracted.  The water is discharged to the aquifer via a separate well (See Fig.3).  This system typically requires a water supply of 20 litres (5 gallons) a minute.

Geothermal Energy with Copper Pipe:

Geothermal Energy with Plastic (HDPE) Pipe: