When a lake, pond or other body of water is conveniently located, it offers the potential of a source of heat, as well as a heat rejection sink.
In-ground - or more precisely in this case, water-coupling - pipe coils are submerged several feet below the low water level. This is typically at a level where the water does not freeze in winter, usually a depth of eight feet or more.
- Never place a loop in moving body of water subject to flooding. Flood stages can destroy the loop.
- Use at least a 20 percent by volume of an antifreeze fluid.
- The body of water should be close to the structure. If the distance to the water and back would accommodate a horizontal field, the submerged loop would offer no advantage.
Installations normally use a parallel configuration. The supply header is on one side, loops in the middle and the return header on the other side.
A word of caution: The performance of these systems is hard to predict due to water stratification, algae growth and other such factors.