A geothermal heat pump system is a heating and/or an air conditioning system that utilizes the Earth's ability to store heat in the ground and water thermal masses. This system will take advantage of a land mass as a heat exchanger to either heat or cool a building structure. These systems operate on a very simple premise; the ground, below the frost line, stays at approximately 50 °F (10 °C) year round and a water-source heat pump utilizes that available heat in the winter and puts heat back into the ground in the summer. A geothermal system differs from a conventional furnace or boiler by its ability to transfer heat versus the standard method of producing the heat. As energy costs continue to rise and pollution concerns continue to be a hot topic; geothermal systems may hold a solution to both of these concerns. A particular advantage is that they can use electricity produced from renewable sources, like solar and wind power, to heat spaces and water much more efficiently than an electric heater. This allows buildings to be heated with renewable energy without transporting and burning biomass on site, producing biogas for use in gas furnaces or relying solely upon solar heating. Geothermal heat pump systems are straight forward and do not require high tech components. Image File history File links No higher resolution available. ... All-air and air-water HVAC systems use air ducts, outlets, and inlets installed throughout their buildings. ... Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ... Thermal mass, in the most general sense, is any mass that absorbs and holds heat. ... A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ... The frost line is the level down to which the soil will normally freeze each winter in a given area. ... A diagram of a simple heat pumps vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor. ... A furnace is a device for heating air or any other fluid. ... A boiler is a closed vessel in which water or other fluid is heated under pressure. ... Lightning strikes during a night-time thunderstorm. ... World renewable energy in 2005 (except 2004 data for items marked* or **). Enlarge image to read exclusions. ... Solar power describes a number of methods of harnessing energy from the light of the sun. ... Worldwide installed capacity and prediction 1997-2010, Source: [http://www. ... A furnace is a device for heating air or any other fluid. ... Switchgrass, a hardy plant used in the biofuel industry in the United States Rice chaff. ... Biogas-bus in Bern, Switzerland Biogas typically refers to a (biofuel) gas produced by the anaerobic digestion or fermentation of organic matter including manure, sewage sludge, municipal solid waste, biodegradable waste or any other biodegradable feedstock, under anaerobic conditions. ... Solar heating is a style of building construction which uses the energy of sunshine to heat a structure. ...

Components

Geothermal systems require three primary components; a loop field on the property, a liquid pump pack and a water-source heat pump. A loop field can be installed horizontally or vertically on the property; we will focus on the different types of loop fields later in this article. The purpose of the loop field is to transfer heat to and from the ground. The size of the loop field depends on the size of the building the system is conditioning. Typically, one loop has the capacity of one ton or 12,000 British thermal units per hour (BTU/h) or 3.5 kilowatts. An average house will range from 3 to 5 tons (10 to 18 kW) of capacity. The second component is a liquid pump pack, which is what sends the water through the loop field and the water-source heat pump. An example of an installed liquid pump pack can be seen in the image just below. Lastly, the water-source heat pump is the unit that replaces the existing furnace or boiler. This is where the heat from the loop field is transferred for heating the structure. Heat pumps have that ability to capture heat at one temperature reservoir and transfer it to another temperature reservoir. An example of a heat pump is a refrigerator; heat is removed from the refrigerator's compartments and transferred outside of the cool refrigerated compartments (see the article on heat pumps for more information regarding heat pumps). Image File history File linksMetadata No higher resolution available. ... The British thermal unit (BTU or Btu) is a unit of energy used in the United States. ... The kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ... “Freezer” redirects here. ... A diagram of a simple heat pumps vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor. ...

Common loop fields

• Closed loop fields: A closed loop system, the most common, circulates the fluid through the loop fields’ pipes. In a closed loop system there is no direct interaction between the fluid and the earth; only heat transfer across the pipe. There are three common types of closed loop systems; vertical, horizontal, slinky and Pond (slinky and pond loops depicted below).

• Vertical closed loop field: A vertical closed loop field is a composed of pipes that run vertically in the ground. A hole is bored in the ground, typically, 150 to 250 feet deep into the ground with a U-shaped loop placed inside the hole.^[1] A vertical loop field will typically be used when there is a limited square footage of land available.

• Horizontal closed loop field: A horizontal closed loop field is composed of pipes that run horizontally in the ground. A long horizontal trench, deeper than the frost line, is dug and U-shaped coils are placed horizontally inside the same trench. A trench for a horizontal loop field will be similar to one seen under the slinky loop field; however, the width strictly depends on how many loops are installed. Horizontal loop fields are very common and economical if there is adequate land available.

• Slinky closed loop field: A slinky closed loop field is also in the horizontal orientation; however, the pipes overlay each other. The easiest way of picturing a slinky field is to imagine holding a slinky on the top and bottom with your hands and then move your hands in opposite directions. A slinky loop field can be used if there is not adequate room for a true horizontal system, but it still allows for an easy installation. The image below shows a 3-ton slinky loop prior to it being covered up with soil. In the picture you can see the three slinky loops being ran out horizontally and three straight lines returning the end of the slinky coil to the heat pump.

• Closed pond loop: A closed pond loop is not as common, but has been coming increasingly popular. A pond loop is achieved by placing coils of pipe at the bottom of an appropriately sized pond or water source. This system has been promoted by the DNR (Department of Natural Resources); who support geothermal systems and the use of ponds for geothermal systems. The two images below show a pond loop close up and the pond loop as it about to be sunk to the bottom of a pond. This loop field is for a 12-ton system, which is unusually large for most residential applications. As you can tell by the pictures; a pond loop is extremely similar to a slinky loop, with the exception of it being attached to a frame and located in a water versus soil.

• Open loop field: In contrast to the closed loop systems, an open loop system pulls water directly from a well, lake or pond for conditioning purposes. Water is pumped directly into the heat pump where the heat is extracted and then is re-injected into the water source or return well.

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Common heat pumps

There are also different types of water-source heat pumps. Residentially and commercially, there is a variation of products available; primarily there are water-to-air heat pumps, water-to-water heat pumps and hybrids between the two. Some manufactures are now producing a reversible heat pump for chillers also. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ...

• Water-to-air: The water-to-air heat pumps are designed to replace your forced air furnace and possibly the central air conditioning system. The term water-to-air signifies that the heat pump is design for forced air applications and indicates that water is the source of heat. The water-to-air system is a one central unit that is capable of producing heat during the winter and air conditioning during the summer months. There are variations of the water-to-air heat pumps that allow for split systems, high-velocity systems, and ductless systems.

• Water-to-water: A water-to-water heat pump is designed for a heating-system that utilizes hot water for heating the building. Systems such as radiant underfloor heating, baseboard radiators and conventional cast iron radiators would use a water-to-water heat pump. The water-to-water heat pump uses the warm water from the loop field to heat the water that is used for conditioning the structure. Just like a boiler, this heat pump is unable to provide air conditioning during the summer months.

• Hybrid: A hybrid heat pump are capable of producing forced air heat and hot water simultaneously and individually. These systems are largely being used for houses that have a combination of under-floor and forced air heating. Both the water-to-water and hybrid heat pumps are capable of heating domestic water also. Almost all types of heat pumps are produced commercially and residentially for indoor and outdoor applications. No images available

Underfloor heating is a unique traditional form of central heating gaining newfound popularity. ...

Characteristics

Geothermal systems are able to transfer heat to and from the ground with minimal use of electricity. When comparing a geothermal system to an ordinary system a homeowner can save anywhere from 30% to 70% annually on utilities. Even with the high initial costs of purchasing a geothermal system the payback period is relatively short, typically between three and five years. Geothermal systems are environmentally friendly; they are a renewable energy source, non-polluting, and recognized as one of the most efficient heating and cooling systems on the market. The life span of the system is longer than conventional heating and cooling systems. Most loop fields are warranted for 50 years. Geothermal systems do not use fossil fuels for heating the house and eliminate threats cause by combustion, like carbon monoxide poisoning. The fluids used in loop fields are designed to be biodegradable, non-toxic, non-corrosive and have properties that will minimize pumping power needed. Some electric companies will offer special rates to customers that install geothermal systems for heating/cooling their building. This is due to the fact that heat pumps only use electricity for heating and no fossil fuels are being purchased. Electrical plants have the largest loads during summer months and much of their capacity sits idle during winter months. This allows the electric company to use more of their facility during the winter months and sell more electricity. World renewable energy in 2005 (except 2004 data for items marked* or **). Enlarge image to read exclusions. ...

Today there are now more than 1,000,000 geoexchange installations in the United States. The current use of geothermal heat pump technology has resulted in the following emissions reductions:

• Elimination of more than 5.8 million metric tons of CO2 annually
• Elimination of more than 1.6 million metric tons of carbon equivalent annually

These 1,000,000 installations have also resulted in the following energy consumption reductions:

• Annual savings of nearly 8 billion kWh
• Annual savings of nearly 40 trillion Btus of fossil fuels
• Reduced electricity demand by more than 2.6 million kW

The monumental impact of the current use of geoexchange is equivalent to:

• Taking close to 1,295,000 cars off the road
• Planting more than 385 million trees
• Reducing U.S. reliance on imported fuels by 21.5 million barrels of crude oil

per year.

External links

• Geothermal Heat Pumps (US Department of Energy)
• GeoExchange Heating and Cooling Systems: Fascinating Facts
• Geothermal Heat Pump Consortium
• Geothermal Heat Pump Manufacturer