Throughout the year, outdoor temperatures fluctuate with the changing seasons. However, underground temperatures do not. In fact, about four to 6 feet below the earth's surface, temperatures remain relatively constant year-round. A geothermal system, which consists of an indoor unit and a buried earth loop, capitalizes on these constant temperatures.
In the winter, fluid circulating through the system's earth loop absorbs stored heat and carries it indoors. The indoor unit compresses the heat to a higher temperature and distributes it throughout the building. In the summer, the system reverses, pulling heat from the building, carrying through the earth loop and depositing it in the cooler earth.