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.
Frequently Asked Questions
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.
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).
A geothermal system is over five times more efficient in heating and more than twice as efficient in cooling as the most efficient ordinary system. Because geothermal systems move existing heat rather than creating it through combustion, they provide four to five units of energy for every one unit used to power the system.
Heating and cooling systems carry an efficiency rating which is certified by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI). Fossil fuel furnaces use AFUE. Air conditioners use SEER while heat pumps use HSPF and SEER.
Geothermal heat pumps rate heating efficiencies 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. The WaterFurnace 7 Series holds the highest recorded certified performance of 5.3 COP in a closed loop and 5.9 in an open loop. That means for every dollar of energy used to power the system, up to $5.90 of energy are supplied as heat. Where a fossil fuel furnace may be 78-98% efficient, a geothermal heat pump is over 500% efficient.
For cooling, geothermal units are rated in Energy Efficiency Ratio (EER). This is a measure of the instantaneous energy efficiency of cooling equipment. The higher the EER, the more efficient the unit. The WaterFurnace 7 Series carries a certified rating of 41 EER for closed loop and 53.2 EER for open loop. This is more than twice as efficient as any traditional heat pump or air conditioner and a third higher than any other two-stage geothermal heat pump.
No. Geothermal systems are practically maintenance free. The buried loop will last for generations. The unit’s fan, compressor and pump is housed indoors, protected from the weather and contamination. Usually, periodic checks and filter changes are the only required maintenance.
While Ross and Witmer does offer an outdoor geothermal unit for jobs where space is limited, its rugged housing is sealed so that no components are exposed to the elements.
Geothermal systems work with nature, not against it. They emit no greenhouse gases – which have been linked to pollution, acid rain, and other environmental hazards. Ross and Witmer’s earth-loop antifreeze will not harm the environment in the unlikely event of a leak. And all of the current product lines use R-410A, a performance-enhancing refrigerant that will not harm the earth’s ozone layer.
No. There are different kinds of geothermal heat pumps designed for specific applications. Many geothermal heat pumps, for example, are intended for use only with higher temperature ground water encountered in open-loop systems. Others will operate at entering water temperatures as low as 25°F, which are possible in closed-loop systems. Most geothermal heat pumps provide summer air conditioning, but a few brands are designed only for winter heating. Geothermal heat pumps also can differ in the way they are designed. Self-contained units combine the blower, compressor, heat exchanger and coil in a single cabinet. Split systems (such as the WaterFurnace Envision Series Split) allow the coil to be added to a forced-air furnace and utilize the existing blower.
Heat pumps don’t create heat. They take existing heat and move it. Anyone with a refrigerator has witnessed the operation of a heat pump. Refrigerators collect heat from the unit’s interior and move it to the exterior for cooling purposes. Unlike a refrigerator, a heat pump can reverse itself. An air-source heat pump, for example, can extract heat from outdoor air and pump it indoors for heating purposes.
A geothermal heat pump works the same way, except that its heat source is the warmth of the earth. The process of elevating low-temperature heat to over 100°F and transferring it indoors involves a cycle of evaporation, compression, condensation and expansion. A refrigerant is used as the heat-transfer medium which circulates within the heat pump. The cycle starts as the cold liquid refrigerant passes through a heat exchanger (evaporator) and absorbs heat from the low-temperature source (fluid from the ground loop). The refrigerant evaporates into a gas as heat is absorbed.
The gasseous refrigerant then passes through a compressor where the refrigerant is pressurized, raising its temperature to more than 180°F. The hot gas then circulates through a refrigerant-to-air heat exchanger where heat is removed and pumped into the building at about 100°F. When it loses the heat, the refrigerant changes back to a liquid. The liquid is cooled as it passes through an expansion valve and begins the process again. To work as an air conditioner, the system’s flow is reversed.
One thing that makes a geothermal heat pump so versatile is its ability to be a heating and cooling system in one. With a simple flick of a switch on your indoor thermostat, you can change from one mode to another. In the cooling mode, a geothermal heat pump takes heat from indoors and transfers it to the cooler earth through either groundwater or an underground earth loop system. In the heating mode, the process is reversed.