Geothermal Horizontal Loop
If adequate soil or clay based land is available, horizontal geothermal ground loops are typically one of the more economical choices. In horizontal geothermal ground loops, several hundred feet of five to six feet deep trenches are dug with a backhoe or chain trencher. Piping is then laid in the trench and backfilled. A typical horizontal ground loop will be 400 to 600 feet long for each ton of heating and cooling. Because of the amount of trenching involved, horizontal ground loops are most commonly used for new construction. Finally, because horizontal geothermal ground loops are relatively shallow, they are often not appropriate for areas with extreme climates such as the north or deep south.
Slinky coil geothermal ground loops are gaining popularity, particularly in residential geothermal system installations. Slinky coil ground loops are essentially a more economic and space efficient version of a horizontal ground loop. Rather than using straight pipe, slinky coils, as you might expect, use overlapped loops of piping laid out horizontally along the bottom of a wide trench. Depending on soil, climate and your heat pumps’ run fraction, slinky coil trenches can be anywhere from one third to two thirds shorter than traditional horizontal loop trenches.