Geothermal heat pumps

One of the most cost-effective ways to make your house more comfortable year-round could be right beneath your feet. Much of the heating and cooling can come from an energy-efficient source known as a geothermal heat pump.

These systems are similar to ordinary heat pumps, but use the ground instead of outside air to provide heating, air conditioning and, in most cases, hot water. Because they use the earth’s natural heat, they are among the most efficient and comfortable heating and cooling technologies available today.

Geothermal heat pumps, also known as ground source heat pumps, can be used almost anywhere in the country because all areas have nearly constant shallow ground temperatures, although systems in different locations will have varied degrees of efficiency and cost savings.

There are four basic types of geothermal heat pump systems. Three of these – horizontal, vertical and pond/lake – are closed-loop systems. The fourth type is the open-loop option, which is similar to a well. This type of system uses a well or surface water for heating and cooling. Less common standing column well systems are used in localities that permit the groundwater to flow outside of a closed loop system.

There are also hybrid systems that combine different design techniques to get the most heat out of the ground.

Several factors – such as climate, soil conditions, available land and local installation costs – determine which system is best for a site.

Most closed-loop geothermal heat pumps circulate an antifreeze solution through a closed loop – usually made of a high density plastic-type tubing – that is buried in the ground or submerged in water. A heat exchanger transfers heat between the refrigerant in the heat pump and the antifreeze solution in the closed loop.

A knowledgeable geothermal heat pump designer balances the yard size and soil conditions with the expected home energy use to develop the best heat pump configuration.