How Does A Geothermal Heat Pump Work?

When we think of the word “geothermal” many people envision hot steam that is tapped deep underground and used on the surface to turn turbines and make electricity. Geothermal energy is simply potential thermal energy of any kind that is trapped in the ground, and which can be used on the surface for a vareity of purposes. The way that a ground source heat pump works is very much similar to a conventional HVAC. Both will likely use R-22 refrigerant, a compressor and evaporator unit. Both systems are designed to do basically the same thing, which is to heat or cool the air in your home. The difference is that the conventional HVAC or heat pump is using outside air as the medium from which heat or cold is exchanged. When it is fifteen degrees Fahrenheit on a cold North Dakota morning, a conventional heat pump will be working especially hard to pull heat out of the frigid air and convert it to 80 degree air inside the house. A geothermal heat pump on the other hand would have the advantage of using the temperature of the ground a few feet under the surface, which might be fifty degrees or more, to make that 80 degree air. Since you’ve spotted the system several degrees it won’t have to use as much energy. SEER ratings, a measure of air conditioner energy efficiency, are very hard to apply to heat pumps. This is because these numbers tend to be based on seasonal air temperature changes. Since the temperature of the ground remains basically the same year round this makes it hard to use SEER to rate geothermal heat pumps. Also, since many systems can make “free” hot water for a home as well, this adds even more energy efficiency to the unit. Most installers agree that ground source heat pumps are anywhere from thirty percent to fifty percent more energy efficient than the most efficient air exchange HVAC and heat pump units.