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Geothermal SystemsMy favorite heating and cooling systems are geothermal heating system technologies (ground source heat pumps). My company installed it’s first geothermal system in 1993. I was intrigued by the idea of heating a home with heat coming from the ground. How a geothermal heating system works The basic concept: Tubing is buried in the ground and absorbs heat that is contained in the earth, then is transferred into the living space. The technology is the same as your refrigerator. There are a few different ways the heat is absorbed from the ground. The most common is a closed loop system.
This is a series of plastic pipes buried in the ground. Glycol (anti-freeze) is pumped through the tubes and picks up heat from the ground and transferred through a heat exchanger that is connected to a refrigeration compressor. A low temperature refrigerant is pumped through the same heat exchanger. The glycol and refrigerant have separate passageways that isolates the two in the heat exchanger. The refrigerant absorbs the heat from the glycol, then compresses it to a high temperature, which is then transferred into the living area through a coil, fan and duct system. Another type of geothermal heating system is called direct-exchange.
It work pretty much the same as a closed loop system, but the refrigerant to glycol heat exchanger is eliminated. I installed these types that were produced by a company called U.S. Power. There were design problems and I was stuck with the warranties. Luckily, I found ECR Technologies, a geothermal manufacturer in Lakeland, Florida. They had a solution to the design flaws in the U.S. Power system. I purchased a retrofit kit from them and the problems went away. ECR calls their system the Earh Link system and states it has the highest COP and EER efficiency rating of any system tested by ARI. COP = Coefficient of Performance or the heating performance of heat pumps. Typical COP’s are approximately 3.5 – 4.0. The higher the COP the less it costs to heat your home. Water Furnace, an established manufacturer of ground source heat pumps now has a unit with a COP of 5.0. Another type of geothermal are water source heat pumps. Instead of glycol being pumped through a heat exchanger, water is pumped from a well and then through the heat exchanger. These units require a higher electrical consumption because of the cost of operation of running a well pump. Another problem is the fouling of the heat exchanger from various water conditions. Comparative cost of operation with fossil fuels Criteria:
Below are the fuel units required and costs to heat the home for one hour at with the above conditions;
Please remember, this example is a very cold day. An average winter day would more likely be ½ the energy as the above example. Is it a green product? On the surface geothermal appears to be very environmentally friendly. There’s no combustion taking place to create pollution and the energy comes out of the earth, it seems so natural. The perception can change for certain situations. Geothermal systems are powered by electricity. If you are tied to a utility grid where electricity is generated from a coal-fired plant, the earth-friendliness goes out the window. It doesn’t have to be that way. You have a choice in most states to purchase clean, renewable energy such as wind power, solar and biogas. Another option is to install a photovoltaic system on your premises. Why I like geothermal
Properly installed, you can enjoy many years of comfort and reliability.
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