GeoSource Heat Pump Handbook

Heating and cooling

What is a heat pump? A heat pump is a mechanical device used for heating and cooling which operates on the principle that heat can be pumped from a cooler temperature to a warmer temperature (cold to hot). Heat pumps can draw heat from a number of sources, eg, air, water, or earth, and are most often either air-source or water-source.

Although heat pumps have been around for more than a 100 years, the technology has dramatically increased. Not only do heat pumps still operate the common refrigerator, but today, heat pump technology allows us to heat and cool residential and commercial buildings. Because of modem innovation, people using heat pumps are now able to save 50-70 percent on their annual heating and cooling costs.

Types of Heat Pumps

Air Source Heat Pump

The air source heat pump exchanges heat between the outside air and the inside air. When the outside air temperature is between 4O°F and 90°F these units are relatively efficient. However, as the temperature difference between the outside and inside air increases, the efficiency of the unit decreases. To overcome the loss of heating capacity these units require auxiliary electric heaters.

Water Source Heat Pump

The water source heat pump exchanges heat between water and the inside air. The water source heat pump is commonly used in commercial buildings using a boiler and cooling tower which keeps the loop water temperature between 60°F and 90°F. As a rule water source heat pumps have a lower operating cost but higher initial cost than air source heat pumps. This difference is due to water side costs of the system rather than air side cost.

Ground Source Heat Pump (GeoSource)

The GeoSource heat pump utilizes the earth as the medium from which heat is extracted. Water is pumped through a heat exchanger in the heat pump. Heat is extracted, and the water is then returned to the ground, either through discharge on a drain field or through a closed earth loop system. Because ground temperatures do not vary as dramatically as outside air temperatures, the heat available for transfer, as well as the unit’s operating efficiency remains relatively constant throughout the winter.

At depths of 15 feet or more below the ground, the soil maintains a year-round temperature of about 43°F -52°F in this region. So in the summer, it’s cooler than the outside air, and in the winter, it’s warmer–making it an ideal energy source.