Geothermal heating and cooling is a relatively simple process which works by taking heat out of the relatively warm ground in the winter and using it to heat the building. In the summer the process reverses and the system takes heat out of the building and puts it into the ground. It does not matter whether the house is heated using hot air or hot water and cooled using cool air or cool water. The basic process works just the same.

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The picture shows the ground loop to the right of the building, the geothermal heat pump and air handler in the center of the building and a combination of a simple duct system for forced air and a radiant floor system.

The ground loop can have various configurations but it is essentially a length of tough polyethylene pipe through which a mixture of water and antifreeze is circulated. In the winter the loop fluid gains heat as it circulates through the pipe. In the summer it loses heat as it circulates.

The geothermal heat pump relies on the same heat pump principle used in nearly all refrigerators and standard air conditioners. In the winter it takes heat from the ground loop fluid and puts it into the air or water which is used to heat the house. In the summer it takes heat from the air in the house and puts it into the ground loop fluid. A conventional air conditioner only differs from a geothermal system working in cooling mode in that it puts the heat from the house out into the hot air outside. This is far less efficient than putting the heat into the cool ground as a geothermal system does particularly in very hot weather.

Many people have difficulty understanding how they can heat their home to 70° when the temperature of the ground is only about 51°. We must not confuse temperature with heat. Even though an object is relatively cold we can still take ‘heat’ out of it and put the ‘heat’ into something that is warm and so make it hotter.

That's it in a nutshell but for more details, click here.