What Types of Electric Heat Pumps are Available?
The air-to-air heat pump is the most commonly used electric heat pump, but there are three other types of units presently on the market. Water-to-air heat pumps exchange heat with either groundwater, surface water, or water passed through cooling towers (for industrial or commercial use). Systems that use groundwater appear to have the greatest potential for efficient and economical operation because groundwater temperatures hover around 50 degrees F most of the year on the average. Ground-source heat pumps are also efficient. Since ground temperatures below the frost line remain relatively constant throughout the year, it is a good heat source for heat pumps. The heat exchange loop can be either vertical, which entails drilling a very deep hole through which the coil passes, or horizontal, in which case the coil is laid in long, relatively shallow trenches. For optimal efficiency, the ground surrounding the coil should be moist, especially for cooling. Another system is the dual-fuel
