Closed-Loop Heat Pump

Closed-loop, ground-coupled systems use a vertical or horizontal heat exchanger buried below the frost line to collect or reject heat. There are two different types of medium that can be used in the exchanger, water or refrigerant. The water source heat pump uses a heat exchanger that circulates water in a closed loop to reject or collect heat from the ground, lake, or pond. The water is treated to prevent freezing and to reduce corrosion and scaling. Horizontal heat exchangers need approximately 500 feet of coil for each ton of cooling capacity. Vertical heat exchangers need about 300 feet of underground coil per ton. The direct exchange heat pump, also called direct expansion, circulates refrigerant, rather than water, in a buried copper pipe heat exchanger. These systems are potentially even more efficient than water loop systems.

Ground-coupled heat pump systems are most appropriate where land is available for burying the pipe and soil conditions are suitable for easy excavation or drilling. However, material and installation costs should always be estimated for your situation since general guidelines can be misleading.