How a Geothermal Heat Pump Works
This Old House plumbing and heating expert Richard Trethewey explains how to capture the heat buried deep in the ground
In this video, This Old House plumbing and heating expert Richard Trethewey explains how to capture the heat buried deep in the ground.
1. All geothermal systems extract heat from belowground where the year-round temperature is about 50F.
2. A closed-loop well consists of a series of horizontal coils that are filled with anti-freeze and buried at least 5 feet belowground.
3. Closed-loop wells can also be installed vertically in deep holes drilled hundreds of feet down into the earth.
4. An open-loop geothermal system pumps water—not anti-freeze—from the ground through the heat pump, and then back into the ground.
5. During winter, the ground water or anti-freeze is pumped into the heat pump where heat is transferred to a closed-loop of liquid refrigerant.
6. The refrigerant flows into a compressor that uses electricity to compress the refrigerant, turning it into a superheated gas.
7. The hot gas flows through a series of coils. Air is blown across the coils, where it's heated and then delivered to rooms throughout the house.
8. The hot gas is then cooled by the air and turned back into a liquid refrigerant where the process starts all over again.
9. In the summer, a geothermal system cools the house by simply pumping the refrigerant in the opposite direction.