Geothermal Basics
- How does a geothermal heating and cooling system work?
- What makes a geothermal system different from ordinary systems?
- What are the components of a geothermal system?
- How efficient is a geothermal system?
- Is the efficiency rating actual or just a manufacturer's average?
- Do geothermal systems require much maintenance?
- What does geothermal mean for the environment?
How does a geothermal heating and cooling system work?
Outdoor temperatures fluctuate with the changing seasons but underground temperatures don't. Four to six feet below the earth's surface, temperatures remain relatively constant year-round. A geothermal system, which typically consists of an indoor unit and a buried earth loop, capitalizes on these constant temperatures to provide "free" energy. In winter, fluid circulating through the system's earth loop absorbs stored heat and carries it indoors. The indoor unit compresses the heat to a higher temperature and distributes it throughout the building. In summer, the system reverses, pulling heat from the building, carrying it through the earth loop and depositing it in the cooler earth.
What makes a geothermal system different from ordinary systems?
Unlike ordinary systems, geothermal systems do not burn fossil fuel to generate heat; they simply transfer heat to and from the earth to provide a more efficient, affordable and environmentally friendly method of heating and cooling. Typically, electric power is used only to operate the unit's fan, compressor and pump.
What are the components of a geothermal system?
The three main parts consist of the heat-pump unit, the liquid heat-exchange medium (open or closed loop), and the air-delivery system (ductwork).
How efficient is a geothermal system?
A geothermal system is three to four times more efficient than the most efficient ordinary system. Because geothermal systems do not burn fossil fuels to make heat, they provide three to four units of energy for every one unit used to power the system.
Is the efficiency rating actual or just a manufacturer's average?
All heating and cooling systems have a rated efficiency from a U.S. governmental agency. Fossil fuel furnaces have a percentage efficiency rating. Natural gas, propane
and fuel oil furnaces have efficiency ratings based on laboratory conditions. To get an accurate installed efficiency rating, factors such as flue gas heat losses and cycling losses caused by oversizing, blower fan electrical usage, etc., must be included.
Geothermal heat pumps, as well as all other types of heat pumps, have efficiencies rated according to their coefficient of performance or COP. It's a scientific way of determining how much energy the system produces versus how much it uses. Most geothermal heat pump systems have COPs of 3-4.5 (WaterFurnace's E Series is rated up to 4.7). That means for every unit of energy used to power the system, 3-4.5 units are supplied as heat. Where a fossil fuel furnace may be 78-90 percent efficient, a geothermal heat pump is about 400 percent efficient. Some geothermal heat pump manufacturers and electric utilities use computers to accurately determine the operating efficiency of a system for your home or building.
Do geothermal systems require much maintenance?
No. Geothermal systems are virtually maintenance free. When installed properly, the buried loop will last for generations. And the other half of the operation—the unit's fan, compressor and pump—is housed indoors, protected from the harsh weather conditions. Usually, periodic checks and filter changes are the only required maintenance. (Note: WaterFurnace has developed a geothermal unit—the ES Split—that is so rugged and quiet, it can be placed outdoors when that's the best solution).
What does geothermal mean for the environment?
Geothermal systems work with nature, not against it. They emit no greenhouse gases, which have been linked to global warming, acid rain and other environmental hazards. WaterFurnace provides an earth-loop antifreeze which will not harm the environment in the unlikely event of a leak. And much of the WaterFurnace product line uses R-410A, a performance-enhancing refrigerant that will not harm the earth's ozone layer.