Geothermal Heat Pumps – How They Work

Gas furnaces actually create heat, right there in your home. By contrast, heat pumps gather up, combine and transfer (pump) heat from the outside air to the inside of the home.

Heat pumps produce more heat than they consume in power, since they don’t actually need to create the heat like gas furnaces do, but rather they take advantage of heat that is already present in the air. The heat pump method of heating the home is exactly the opposite of how the home is cooled during summer: the air conditioning equipment ‘pumps’ the heat to the outside air in summer. A heat pump is fundamentally an air conditioner that has the ability to reverse the flow of heat, because of the addition of one key component . . . a reversing valve for the refrigerant.

A geothermal heat pump uses the same heat transfer technology, but with one significant difference: the heat exchange outside the home is to and from the relatively constant-temperature ground, by means of pumping a water-based coolant through tubing that is buried about five feet below the surface. It is faster and more efficient to transfer heat to or from the ground than from the air. To help you picture this heat transfer difference, which method of cooling off your body is faster: standing in a swimsuit in 60 degree air, even on a windy day, or jumping into a pool filled with 60 degree water? The transfer of heat by means of contact with a solid object or a fluid is as much as 50 times faster and more effective than heat transfer through the air. Also, the ground remains in a near-constant temperature range that supports easy heat transfer year all year long. This is in contrast with the air, which can range in this area from perhaps 10 degrees below zero to more than 100 degrees above zero as the seasons change.