There are four different kinds of loop systems to power geothermal heat pumps:
Horizontal Loop
The horizontal loop is the most common loop used when adequate land area is available (the home should sit on 1/2 acre, at least). Loop installers use excavation equipment such as chain trenchers, backhoes, directional bore machines, and track hoes to provide trenches approximately 5-8 feet deep. Trench lengths typically range from 100 to 250 feet per ton, depending on the loop design and application.
Vertical Loop
The vertical loop is used mainly when land area is limited and in retrofit applications of existing homes. A drilling rig is used to bore holes at a depth of 150 to 250 feet per ton. A U-shaped coil of high density pipe is inserted into the bore hole. The holes are then backfilled with a sealing solution.
Pond Loop
A pond loop is an option if a large body of water is available within approximately 200 feet of the home. A ½ acre, 10 to 12-foot deep body of water is needed to support the average home. The system uses coils of pipe typically 300 to 500 feet in length. The coils are placed in and anchored just above the bottom of the body of water.
Open Loop
An open loop can be installed if an abundant supply of high quality well water is available. A typical home will require a well producing 4 to 8 gallons of water per minute. A proper discharge area such as a river, drainage ditch, stream, pond, or lake must be present. Check for local restrictions before selecting a specific discharge method.