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Working With It - Designing Open Loop Systems

Water Sources - Lakes, Ponds, etc.

An open lake well diagram 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.

Special considerations

  • 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.

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