The industry of geothermal heat exchange has been around for years. Actually, the Greeks used geothermal heat to heat their hot baths a couple of millennia ago. Geothermal heat as we now apply the term refers to the art of extracting latent geothermal heat from the ground. This does not require that you have a hot spring on your property as the ground absorbs heat through radiation from the sun, even on cloudy days. Most ground at a depth of about eight feet maintains the same temperature year round, with little or no fluctuation. The earth is a great insulator.

The advances in recent years in geothermal heat exchange have allowed us to use electricity and environmentally friendly refrigerants to extract and compound this latent heat. We require ground or water temperature at a minimum of 40° in order to operate a geothermal heat exchange system efficiently. The higher the temperature the more efficient the geothermal heat system.

The heat pump itself consists of primarily a compressor and a heat exchanger. The compressor compresses, much the same as the compressor in your fridge or deep freeze, allowing the system to separate heat from cold. In your freezer it separates the air into warm (goes out the back or under your freezer) and cold (goes into the freezer). A water based geothermal heat exchange system operates on the same fundamentals, except using water, rather than air.

The technology behind the geothermal heat exchangers and compressors has advanced in recent years to attain a level of efficiency, which make them very attractive as alternate heating and cooling methods. Actually, studies carried out by the United States DOE (Department Of Energy) have identified water based geothermal heat exchange systems to be the most efficient and cost effective way to heat and/or cool your home or business - bar none. It makes you wonder why it is considered an "alternate" method?

The geothermal heat pump itself resides in your home and really gets all of the credit for heating and cooling the home, but it is actually the miracle of nature through ground heat that provides the renewable resource which makes the system capable of doing its job on an on-going basis.

Outside of the residence we extract our latent heat source. The earth maintains its constant temperature despite our taking this latent heat through absorption. As long as we have designed and installed our geothermal heat extracting loops (ground loops), or return our heat-extracted water according to established industry standards, this process can be repeated indefinitely.

The real essence of geothermal heat exchange is multi-faceted. It is cheap to operate, and if installed properly, can result in costs that are a fraction of your current fuel bill. Natural gas is the second most effective method for home or business heating, but still cannot compare in operating cost to geothermal heat exchange.

TAX INCENTIVES
There are numerous incentives offered for geothermal heating and cooling systems across the United States.

How a geothermal heat pump works

Geothermal can be used to providing heating or cooling services. In each instance the process is similar.

Geothermal Heating

In the heating mode, the water circulating in the earth loop is colder than the surrounding ground. This causes the water to absorb energy, in the form of heat, from the earth. The water carries this energy to the heat exchanger in the pump. In the heat exchanger, refrigerant absorbs the heat energy from the water. The water now leaves the heat exchanger at a colder temperature, and circulates through the earth loop to pick up more energy.

The refrigerant gas, which contains energy gained from the earth loop, travels from the heat exchanger to the compressor. In the compressor, the refrigerant temperature rises to 160°. From the compressor, the superheated refrigerant travels to the air heat exchanger. Here, the heat pump's blower circulates air across the air coil, increasing the temperature of the air, which is blown through ductwork to heat the home. After refrigerant releases its heat energy to the air, it then flows to the earth loop heat exchanger to start the cycle again.

Geothermal Cooling

In the cooling mode, the water circulating in the earth loop is warmer than the surrounding ground. This causes the water to release energy, in the form of heat, into the earth. The water now cooler from traveling through the ground now flows to the to the heat exchanger in the pump. In the heat exchanger, hot refrigerant gas from the compressor releases its heat into the water. This causes the water to increase temperature, which it releases to the ground.

The refrigerant, which has released its heat energy and became a cold liquid, now travels to the heat exchanger. Here the heat pump's blower circulates warm, humid air across the cold air coil. The air is then blown through ductwork to cool the home. The refrigerant in the air coil picks up the heat energy from the air, and travels to the compressor. When the refrigerant leaves the compressor, it then flows to the earth loop heat exchanger to start the cycle again.

Geothermal Installation

There are four main ways that the earth loop for a geothermal system can be installed. The method you choose depends mainly on the size and features of your property. A dealer will be able to help you evaluate your site and suggest the most appropriate loop type for your situation:

Horizontal Straight Loops consist of lengths of pipe installed into trenches under the lawn that are dug using a backhoe or excavator, approximately five feet underground and below the frost line. This is the most common installation type and is very economical as long as there is adequate land area available to dig the trenches.

In addition to standard trench-based horizontal loops, directional bore loops can be used when the site is heavily wooded or when there is extensive landscaping in place. A machine is used to drill tunnels underneath the yard into which the loop pipes are then installed. This allows the installation to be completed with a minimum of disruption to the existing yard.

Horizontal Coiled Loops are similar to the more common horizontal straight loops, except rather than burying straight runs of pipe, the pipe is spread out in flattened, overlapping coils. This type of loop, also known as a Slinky loop, allows for adequate pipe surface area in shorter trenches, allowing it to fit in some areas where horizontal straight loops would be impractical.

In addition to standard trench-based horizontal loops, directional bore loops can be used when the site is heavily wooded or when there is extensive landscaping in place. A machine is used to drill tunnels underneath the yard into which the loop pipes are then installed. This allows the installation to be completed with a minimum of disruption to the existing yard.

Vertical Loops run deep into the ground and are ideal for properties lacking the larger areas of lawn needed for a horizontal loop. They cost more to install than horizontal loop systems, but they have the advantage that they can be installed on small lots where not enough open land exists to install a horizontal loop.

Vertical loops are also often used for installations at large commercial buildings, because the land area required for horizontal loops for such large buildings is often prohibitive.

Pond Loops take advantage of an existing body of water located on the property to extract energy with a minimum of excavation work required. The coiled loops are floated into the pond, then filled with liquid and sunk to the bottom.

Because there is much less digging required, the pond loop option is often the lowest-cost method for sites that already contain a suitable body of water.