Geothermal Earth Loops
Four basic types of geothermal energy sources:
Closed loop systems circulate a water-based solution through a “loop” of small diameter, underground pipes. Closed loop systems can be installed horizontally, vertically, or in a pond. Open Loop systems utilize an existing water well. Regardless of whether the system is open or closed, heat is transferred to or from the home to provide year-round comfort no matter what the outdoor temperature is.
Horizontal loops are often considered when adequate land surface is available. Pipes are placed in trenches, in lengths that range from 100 to 400 feet.
Vertical loops are the ideal choice when available land surface is limited. Drilling equipment is used to bore small-diameter holes from 75 to 300 feet deep.
Pond (lake) loops are very economical to install when a body of water is available, because excavation costs are virtually eliminated. Coils of pipe are simply placed on the bottom of the pond or lake.
Open loops systems utilize ground water as a direct energy source. In ideal conditions, an open loop application can be the most economical type of geothermal system.