Geothermal Heat Pump Calculator

How It Works

Geothermal (ground-source) heat pumps use the constant temperature of the earth — about 50 to 60 degrees F below the frost line — as a heat source in winter and a heat sink in summer. This gives them a COP (coefficient of performance) of 3.5 to 5.0, meaning they produce 3.5 to 5 units of heat for every unit of electricity consumed. That is 300 to 500 percent efficient, compared to a gas furnace at 80 to 97 percent. There are three main loop types: horizontal loops are cheapest but require large yard space (trenches 4 to 6 feet deep), vertical loops use boreholes 150 to 400 feet deep and work for smaller lots, and pond loops are cheapest if you have a body of water nearby. Soil type matters enormously — rock and saturated clay conduct heat well (shorter loops needed), while dry sand conducts poorly (longer loops). Installation costs are high ($15,000 to $35,000) but the 30 percent federal tax credit (through 2032) and 40 to 70 percent lower operating costs typically yield payback in 5 to 12 years. The systems last 25 years for indoor components and 50+ years for the ground loop.