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What is Geothermal HVAC?

Ken Black
Ken Black

Geothermal HVAC systems are those which use the natural temperature of the ground, often described as heat but it can also have cooling effects, to help heat a structure. While the systems are relatively new and easy to install, they are seen as having great potential to save energy and do so in an environmentally-friendly way. The advantages of geothermal HVAC is that it can supply a limitless supply of heat, or coolant, depending on what is needed.

The natural temperature of Earth just below the surface is somewhat constant, depending on the latitude. While higher latitudes have slightly lower temperatures the closer toward the surface one gets, the further down, the more uniform the temperature becomes. This is because at colder latitudes, more heat is drawn away from just below the surface of the Earth.

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Woman posing

The geothermal HVAC process depends on this constant temperature. Much like a cave will be cooler in the summer and usually warmer in the winter, this is the same concept that such a system will use for climate control. In order to take advantage of this concept, there must be a way to get that constant temperature to the surface and into the air. The geothermal HVAC system is the way to do it.

There are several major parts to a geothermal HVAC system. These include the loop, the heat pump and the duct system. Each part carries out a different part of the task and some are very similar to parts of traditional heating and air conditioning systems, such as the duct system. However, they are also different in important ways.

The loop system is the most expensive part of the system to install. This will likely require some excavation and may require some trial and error to get the loop installed properly, if the ground is very rocky. The loop can be close-ended or open-ended. In an open-ended loop, water is extracted from the ground, used and then discharged back into the ground or on the surface. These are do not meet code in most areas. The close-ended system uses water or antifreeze solution to loop the material in a continuous way.

The heat pump brings the liquid to the surface and can either be responsible for cooling or heating, depending on the need. In some cases, geothermal HVAC systems will need traditional methods of heating and cooling in order to get the desired temperature, but a heat exchanger makes this less of a need. However, even in those situations, the energy savings can be substantial over a more traditional system.

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Discussion Comments


I was curious about the technology of geothermal hvac, so I researched the topic and found the most interesting web-site by a man named Jay Egg. His website was great, but his book was even better. It is called "Geothermal HVAC" and was such a wonderful read. My parents live down in the southeast. I wish that there was an expert like him up in my neck of the woods.

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