Have A Water Source? An Open Loop Geothermal System Might Work

If you’re thinking about using geothermal energy to power your home heating and cooling system, there are several configuration options for installation. Many homeowners with access to nearby water opt for an open loop geothermal system. Using a water-source heat pump connected to your well, pond or lake can work just as well as an air source version. Installation of an open loop geothermal system involves digging shallow trenches that lead to the water source. Pipes laid in the trenches connect your home to a set of looped coils at the bottom of the body of water. In an “open loop” system, water is pumped in from the source, heat is extracted from or added to it, then the water is returned to the source.

In winter, your heat pump heat exchanger coil absorbs heat from the water to heat your house. In summer, it offloads excess heat into the water to cool your living space. The actual absorption and emission of the heat is done through a chemical reaction as refrigerant continually runs through your heat pump, transferring the heat. When determining if an open loop geothermal system is right for you, the main factors to consider are:

• Well, pond or lake capacity: You’ll need about 1½ gallons per minute, for each ton of heating/cooling capacity required by your home. When the same source is used for household water, factor it into the total. Flow must increase in winter when water temperature falls to 40 degrees, to keep emitted water above freezing.
• Local water chemistry: Mineral content, pH and temperature must be evaluated to ensure water scale doesn’t impede or damage the water coil and heat exchange equipment.
• Water pumping cost: If the distance the water supply must be lifted/pumped against gravity is realistic, an extremely efficient, variable speed ECM (electronically commutated motor) should minimize operating costs, saving money long term.

To learn more about geothermal systems, contact the experts at Sobieski Services. Our goal is to help educate our customers in Delaware, Pennsylvania, Maryland and New Jersey about energy and home comfort issues (specific to HVAC & plumbing systems).

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