closed loop - vertical

With closed geothermal ground loops, antifreeze runs through the system.

Both an abundant source of clean water and an adequate runoff area are required for a successful open loop system. While double well designs can be economical, use of open geothermal ground loops is generally discouraged and even prohibited in some jurisdictions. Water quality is key to an open loop design as mineral content and acidity can quickly damage geothermal units.

Also, improper installation or runoff management of an open loop geothermal system can result in ground water contamination or depleted aquifers.