Pond Loop Installation
As is common in many parts of the midwestern United States, local zoning rules required WaterFurnace to construct a retention pond for storm-water runoff as part of the new facility's construction. WaterFurnace saw this as a great opportunity to combine a beautiful focal point with a cost-effective water loop installation. A three-acre pond dominates the front of the facility, which overlooks a major thoroughfare. In instances like this, where water retention is an issue, pond loops are by far the most cost-effective method of heat exchange. The pond is also used as a source of water for the lawn sprinkler system.
The water loop system consists of 12 heat-exchanger zones spread over the bottom of the pond, which is eight feet deep. Each zone is constructed from fifteen 300-foot-long coils of three-quarter-inch thermoplastic pipe connected to the building by two-inch supply and return lines. A heat fusion process that forms an unbreakable connection stronger than the pipe itself joins the high-density polyethylene piping used for the loop.
During the first five summers of operation, the maximum temperature of the water inside the loop was 85° F during periods of 100° F and higher outdoor air temperatures. In these conditions, the WaterFurnace units cool with an energy efficiency ratio (EER) of 16, which is about double that of conventional cooling. During the winter, when the pond is frozen at the surface, water loop temperatures are a minimum of 35° F. Under these conditions, the units heat with a coefficient of performance (COP) of 4. This is four times more efficient than electric resistance heating and provides considerable savings when compared to the highest-efficiency gas systems.
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