A geothermal heating and cooling system operates on the same time-tested principles as your kitchen refrigerator. Through simple cycles of compression and expansion, a closed system of refrigerant is converted from its gaseous state to its liquid state and back in order to facilitate heat exchange. Just as your refrigerator takes heat from inside the refrigerator and moves it into your kitchen to cool the interior space, a geothermal heat pump takes heat from the earth and pumps it into your home during the winter. Run in reverse during the summer, the system removes heat from inside your home and pumps it into the earth, your water heater or pool.
Whereas conventional heating systems generate heat by burning fossil fuels, geothermal systems simply pump existing heat from one area to another. Use of geothermal heat pump technology is guaranteed to provide the homeowner with both higher energy efficiency and a lower environmental footprint than any other system available today or in the foreseeable future.
There are three primary components to a geothermal HVAC system: the ground loop, the heat pump equipment and the distribution system.
The Geothermal Ground Loop: The ground loop is a heat exchanger that enables the geothermal system to exchange heat with the earth. It is a core component that sets geothermal systems apart from traditional heating and cooling systems which burn fossil fuels to create heat in the winter and transfer heat outside the home via foundation A/C units in the summer.
The ground loop takes advantage of the fact that the earth's average temperature remains relatively constant year-round once you go below eight or ten feet. Depending on the system design, either a water-based solution or system refrigerant circulates through a closed ground loop which is usually installed in vertical wells drilled deep into the earth.
Coolant is circulated through the loop, through the heat exchanger in the heat pump and back into the earth. In the winter, the heat pump extracts heat from the loop and puts the heat in your home. In the summer, heat is pumped out of the house and is rejected to the ground loop or it can be used for domestic hot water or pool heating applications.
The ground loop allows the heat pump system to move existing heat from one place to another which is inherently more efficient than traditional oil or gas combustion systems. Once the ground loop is designed, installed and tested, it will operate silently year-round and will require no maintenance whatsoever. The practical life expectancy of the ground loop, which has no moving parts and is located deep in the earth, is virtually unlimited.
Geothermal Heat Pump Equipment: The heat pumps used in geothermal HVAC systems are advanced refrigeration systems that have been configured to pump heat back and forth between your home and the earth via the ground loop. Just as your refrigerator moves heat from inside the refrigerated space to your kitchen, in the winter the geothermal heat pump moves heat from the ground loop to the radiant or circulating air heating system in your home. In the summer the heat pump works in reverse to move heat from inside your home to the ground loop or is used for other applications.
While this is a simplified way to look at a sophisticated system, the salient fact is that the basic principles of geothermal systems are as proven and dependable as the refrigerator in your kitchen. Geothermal heat pumps are built to very high standards of quality and can be expected to last 25 years or more, considerably longer than traditional systems. Just like your refrigerator, geothermal heat pumps are quiet and they require no regular maintenance other than air filter service.
The Distribution System: Geothermal systems lend themselves to virtually any heating or cooling application, residential or commercial, large or small. An ideal way to configure a high-end residential geothermal HVAC system is the combination of radiant floor heat with a forced-air duct system. In most applications, this configuration allows for the most stable and comfortable home environment. With the addition of humidity control and electronic air cleaners, a geothermal radiant/forced-air system is guaranteed to be the best-performing, most comfortable and most efficient HVAC system for your home.
To further boost efficiency, the 'reject heat' produced by the system during the summer (which would be sent into the earth via the loop) can be used to heat water for your home or it can be used to provide heat for your swimming pool. Whereas a conventional system would cool your home by rejecting heat via noisy outdoor foundation units, while the pool is being heated by a gas-fired unit, a geothermal system can be configured to move summer 'reject heat' to where you can use it at no cost. It is literally free heat.
It is important to understand that geothermal technology is not experimental by any means. In fact, as of 2006, there were well over a million geothermal HVAC systems operating in the U.S. Adoption of geothermal technology in any particular geographic area varies with many factors, but it is generally dependent on the relative economics of geothermal systems versus oil and gas-fired systems. As vertical geothermal well drilling has become more economical in recent years, and, as the public has been made aware of the dangers of increasing carbon emissions, geothermal systems are becoming more common in the Northeast U.S.
