About Geothermal heat pumps
Why Use Geothermal?
A Geothermal (sometimes referred to as Direct Exchange or DX) heat pump system is not only something that makes you feel comfortable, it is a technology that you can feel comfortable about. Because it is lowest in greenhouse emissions, geothermal is the most environmentally responsible heating and cooling alternative available today, according to the Environmental Protection Agency.
Geothermal systems are highly energy-efficient since they only require a relatively small amount of electricity to harness the renewable energy in the earth. These units typically deliver much more energy than they consume, so you save on your monthly energy bills when compared to other types of heating and cooling systems.
By focusing attention on advanced product design, solid construction and installation flexibility, geothermal heat pumps are capable of fully utilizing the natural heat storage ability of the earth as a primary source for heating and cooling your home.
How It Works
No matter where you live, the underground temperature remains relatively constant all year, even though outdoor temperatures may vary widely. Geothermal systems utilize this stable resource as a renewable energy source for your home.
Every geothermal system has three major subsystems or parts:
- An earth loop for transferring heat in the earth
- A heat pump compressor unit to concentrate and move the heat
- An indoor heat distribution system.
(A water-based geothermal heat pump also has a water pump to move water through its water loop in the ground and a water-to-refrigerant heat exchanger.)
In the Winter heating mode, heat is extracted from the earth by using that heat to evaporate the refrigerant (any temperature above -40°F is sufficient) which then passes through the compressor where its pressure and temperature are increased. The hot refrigerant then gives up its heat by heating cool air that passes through the fan coil in the air handler (or by heating the water that is flowing through a radiant hydronic system). Having given up its heat, the refrigerant condenses into a liquid and returns to the earth loop to take on more heat.
In the Summer cooling mode, the process is reversed. The liquid refrigerant passing through the fan coil in the air handler (like the coils in an air conditioner) is evaporated and passes through the compressor where its heat is concentrated and increased. The hot refrigerant vapor then gives up its heat as it circulates in the earth loop, condenses into a liquid, then returns to the building to take on more heat.
(A water-based geothermal heat pump relies upon a water loop to extract heat from the earth and transport it to a heat exchanger adjacent to the heat pump, where the heat is transferred into the heat pump system, and the cycle is reversed in the summer.)
An Investment in Savings
A typical homeowner can save in the range of $600 to $1,200 annually (actual savings vary depending on usage, weather and local utility rates) with the installation of a geothermal system. How? The use of geothermal loops allow geothermal units to use only a relatively small amount of electricity. The unit merely transfers heat to and from the earth, rather than creating it from fossil sources like conventional systems. With geothermal you will enjoy savings up to 60% over conventional systems, and a short investment payback.
Plus, governments and utilities often offer tax credits and rebates for the installation of geothermal heat pumps.
The Importance of AHRI Efficiency Ratings
and ENERGY STAR
Heating and cooling systems are independently rated based on their performance. In the U.S. there are two primary information resources available to the consumer, AHRI and ENERGY STAR. EarthLinked Technologies participates in both programs.
AHRI (Air Conditioning, Heating and Refrigeration Institute) is the trade association representing manufacturers of more than 90% of the central air-conditioning and commercial refrigeration equipment installed in North America. EarthLinked Technologies was one of the founding members of the Direct Geoexchange Section of AHRI that established Standard 870 for performance certification.
Two of AHRI’s most important functions are the development of performance rating standards and the administration of performance certification programs for eligible products. Participation in the program is voluntary and is open to members and nonmembers of AHRI on an equal basis. AHRI regularly selects random samples of equipment for testing. The equipment is tested using procedures set forth in the AHRI standard to verify performance ratings.
To complete the performance test, a heat exchanger is used in lieu of an actual earth loop. EarthLinked efficiencies at AHRI test conditions are 77°F entering fluid in the cooling mode and 32°F entering fluid in the heating mode.
ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy that was created to help consumers save money and protect the environment through energy efficient products and practices.
The EarthLinked® system is in the Direct Expansion (DX) category and is defined by Energy Star as a geothermal heat pump system in which the refrigerant is circulated in pipes buried in the ground (rather than using a heat transfer fluid, such as water or antifreeze solution in a separate closed loop, and a fluid-to-refrigerant heat exchanger).
When tested under AHRI 870 conditions, a DX system must achieve a minimum EER of 15. The Energy Efficiency Ratio (EER) is a measure of cooling efficiency that represents the ratio of total cooling capacity to electrical energy input. The Coefficient of Performance (COP) is a measure of heating efficiency that represents the ratio of total heating capacity to electrical energy input. The minimum requirement for COP is 3.5. The EarthLinked system meets or exceeds that requirement.