This system utilizes the earth's natural heat stored at the bottom of a nearby body of water such as a lake or a pond. The pipe is submerged into the body of water utilizing the water surrounding the plastic tubing (rather than soil) where the heat from the pond water is transferred to the water circulating through plastic loop. The deeper the pond, the less fluctuation in water temperature during extreme outside temperatures. No wells and very little trenching are required with this type system.
