Geothermal Ground Source Heat Pumps
Geothermal ground source heat pumps draw energy from the earth's crust. About 10 to 15 feet below the earth's surface there is a constant temperature (somewhere between 45 and 58 degrees Fahrenheit, depending on where you are). This constant temperature is used to heat homes during winter and cool them during summer.
Solar purists will note that geothermal energy is actually solar energy stored in the earth.
The principle is really very simple
When the air is colder than the ground ten or fifteen feet below the surface, the difference in temperature (heat) is transferred to the inside of the house through a system of piping. Geothermal heat transferred to your house makes it easier for your furnace to heat the air. The opposite principle works during summer: cooler temperatures underground cool your house.
How Geothermal works
The transfer of temperature from outside the house to inside is done a number of ways.
- It can be transferred to a heating or cooling ventilation system.
Since the ground is at a consistent temperature (between 45 and 60 degrees Fahrenheit, depending on the particular ground conditions where you live), it provides a more easily modifiable basic air temperature for your furnace or cooling system. For example, if you want to heat air to 70 degrees Fahrenheit, your furnace will have to do far less work than it normally would.
- It can also be transferred in through a system of pipes in the floor.
The air is already being heated in part by a system of piping running through the flooring of the house. Your gas or electric bill will be far lower (as much as 70% lower) than it would be otherwise. And it provides moderating cooling in summer, too.
This may sound a bit familiar to some people
Closed loop geothermal heat pumps are similar to solar thermal systems: water or anti-freeze circulates through a system of piping. (The pipes can also circulate air, though this is used less often). The temperature (hot in winter and cool in summer) is then transferred to the house through its ductwork.
There are four basic ways this is done. Each of these circulates either water or an anti-freeze solution through an extended system of piping that has been installed under ground. Four different types or systems of piping you can read more about are: