Friday, 1 February 2013
What about Geothermal HVAC for homes

Roger Eldridge, Partner, explains how a geothermal system can save 50% of the energy required to heat and cool a home with conventional systems.

The fact that the earth is always the same temperature year round, the efficiency of the unit is twice what it is with a conventional system so that is where the energy savings is. The efficiency of the system goes up dramatically. A typical heat pump fluctuates efficiency based on the temperature pf the outdoors especially in the winter time. When the temperature goes down, the capacity of the unit decreases until it reaches a point where you get almost nothing out of the system. Geothermal never has that problem. It is always a constant so you are getting the same amount of heat extracted from the earth year round.

Geothermal is a system that uses the earth as a condensing unit. Instead of having a piece of equipment outside of your house it uses the earth as a heat sink. It transfers the energy from heat in the house to the earth and takes energy from the earth to cool the house. It’s a standard heat pump with the only difference it uses wells in the earth as the condensing part of the system instead of the air.

There are two methods; vertical wells and horizontal wells. If you have a 300 foot well four feet under the ground or a vertical well it will provide 2.0 Tons of cooling A 300-500 ft A 300 ft vertical wells will provide the same amount of cooling. You re-circulate water with a mixture of 15% methanol or antifreeze. The earth has a constant temperature always around 60 degrees. The heat pump in the winter time pulls heat from the earth re-circulates it to the heat pump unit where the heat is extracted from the refrigerant and circulated through air. It heats the air up and the air is circulated though the house. In cooling the cycle is reversed. It absorbs heat in the house transfers it to refrigerant, to the water, to the ground, the ground absorbs the heat.

Is auxiliary heat needed with a geothermal system? The only reason we recommend putting any kind of electrical auxiliary heat is purely as emergency backup in case the geothermal heat pump part of the system was to fail so you would not be totally without heat.

Presently until 2016 the Federal Government is offering a 30% tax credit on a primary residence geothermal system which covers the total cost of the installation. I used it myself so I know that for a fact; saved me about $15,000.

The US Environmental Protection Agency (EPA) says geothermal heat pumps are among the most efficient and comfortable heating and cooling technologies currently available, because they use the earth’s natural heat to provide heating, cooling, and often, water heating. Click here for the EPA reports.

Posted on 02/01/2013 1:05 AM by Roger Eldridge
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