Geothermal heat pump is a type of heat pump by which the ground, ground water, or ponds are used as a heat source and heat sink, rather than outside air. The temperatures of ground or water are more constant and as compared to air temperatures they are warmer in winter and cooler in summer. As compared to conventional or air-source heat pumps, geothermal heat pumps operate more efficiently.
Efficiency of Geothermal Heat Pumps
Geothermal heat pumps are sometimes called as GeoExchange, earth-coupled, ground-source, or water-source heat pumps. They have been in use since the late 1940s. As the exchange medium Geothermal heat pumps (GHPs) uses the constant temperature of the earth instead of the outside air temperature.
By doing this the system becomes able to reach fairly high efficiencies i.e. 300%-600% on the coldest of winter nights, this efficiency is 175%-250% for air-source heat pumps on cool days.
While there are many regions in the world where the people experience seasonal temperature extremes from scorching heat in the summer to sub-zero cold in the winter, but during these extreme climate also, there always remains a relatively constant temperature just few feet below the earth’s surface. In the US, the ground temperatures range from 45°F (7°C) to 75°F (21°C), but that depends on latitude. Same as in a cave, during the winter this ground temperature is warmer than the air above it and in the summer cooler than the air. The advantage of this is taken by the GHP by exchanging heat with the earth by means of a ground heat exchanger.
More Efficient than Air- Source Heat Pump
Like any other heat pump, geothermal and water-source heat pumps are such made that they can heat, cool, and, if they are equipped with the facility, then they are also able supply hot water to the house. In order to provide more comfort and energy savings, some models of geothermal systems are available with two-speed compressors and variable fans. If compared to air-source heat pumps, they are relatively quieter, last longer, need little maintenance, and do not depend on the temperature of the outside air.
Dual-Source Heat Pump
In a dual-source heat pump an air-source heat pump is combined with a geothermal heat pump. In these appliances there is a combination of the best of both systems. The efficiency ratings of dual-source heat pumps are higher than air-source units, but they are not as much efficient as geothermal units are. The main advantage of dual-source systems is that their cost of installation is much less than a single geothermal unit and they work almost as well.
Although the installation cost of a geothermal system could be several times that of an air-source system of the same heating and cooling capacity, but you get back these additional costs in energy savings in 5-10 years. It is estimated that the system life is 25 years for the inside components and 50+ years for the ground loop. Each year approximately 40,000 geothermal heat pumps are being installed in the United States.
Types of Geothermal Pumps
The main types of geothermal pumps are:
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Closed – loop geothermal pumps
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Horizontal Ground Loop
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Vertical Ground Loop
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Surface Water Loop
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Open – loop Geothermal pumps
Benefits of Geothermal Heat Pump Systems
The biggest benefit of GHPs is that 25%–50% less electricity is used by them as compared to conventional heating or cooling systems. So we can say that a GHP uses one unit of electricity to move three units of heat from the earth. According to the EPA, geothermal heat pumps have the ability to reduce energy consumption and corresponding emissions up to 44% as compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. Humidity control is also improved by GHPs by maintaining about 50% relative indoor humidity; so GHPs have proved to be very much effective in humid areas.
Design flexibility has been allowed by the geothermal heat pump systems and they are designed such that they can be installed in both new and retrofit situations. The equipment rooms can be greatly reduced in size, providing free space for productive use because the hardware requires less space than what is needed by conventional HVAC systems. An excellent “zone” space conditioning is also provided by GHP systems, this allows different parts of your home to get heated or cooled to different temperatures.
The moving parts of GHP systems are durable and highly reliable as they are relatively few in number, and all those parts are sheltered inside a building. The warranties often carried by underground piping are of 25–50 years, and the heat pumps often last 20 years or more. Usually GHPs have no outdoor compressors, so they are not susceptible to vandalism. On the other hand, the components that are in the living space are easily accessible, by this the convenience factor is increased and it also helps to ensure that the upkeep is done on a timely basis.
There’s no concern about noise outside the home because they have no outside condensing units like air conditioners. A two-speed GHP system works so quietly inside a house that the user hardly able to know that it is operating: there are no tell-tale blasts of cold or hot air.
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{ 3 comments… read them below or add one }
That is a great article. Thank you for sharing.
need to know a little more about geo
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