You would have gone through the first part of this article on Direct Use geothermal heating systems
, by now.
Ground Source Heat Pumps or GSHPs are on the other hand the most sought after heating systems as these are economically and environmentally important. They come in 3 main types.
Ground Coupled Heat Pump systems Ground Water Heat Pump systems Surface Water Heat Pump systems
The use of terminology in Ground Source Heat Pumps is somewhat confusing even to professionals. Therefore those who are interested better be prudent when analyzing the pros and cons of systems.
Ground Coupled Heat Pump systems
A ground coupled heat pump or a Closed Loop Ground-Source Heat Pump is a system incorporating a reversible, vapour compression type (i.e. systems which uses compressor driven refrigeration systems) unitary (packaged) unit coupled to a" refrigerant to water" heat exchanger (Condenser).This is the mostly commonly used residential GCHP in the world and is called "water to air" heat pump.
A closed loop secondary liquid (refrigerant) circuit consisting of water and antifreeze (or at times water only) circulates it through a polyethylene "U" tube buried approximately up to 150 meters (if buried in soil vertically or about a meter below ground surface, if buried horizontally), by means of a pump.
Another more efficient but expensive GCHP uses a buried copper tube type heat exchanger coupled to an Expansion Valve/capillary tube throttling device and a change over valve forming Direct Expansion type GCHP.
GCHPs are further sub divided based on the buried heat exchanger coils as follows;
Vertical
uses generally two small bore high density poly ethylene (HDPE) pipes buried in the bore drilled in the soil at a depth between 15m to 180 m depending on several variables. The two pipes are joined together at the end of them forming a "U" tube. Relatively less surface area is required. Horizontal
Requires a wide surface area. Horizontal system may be found as Single Pipe, Multiple Pipe and Spiral pipe types. The spiral system requires the least amount of area out of the three types. Horizontal GCHP has the advantage of being economical than the vertical. Also trained technical personal are readily available. Unfortunately due to the shallow position of the coil, the ground temperature and the thermal characteristics vary widely with the season, rain fall and the depth of the loop coil.