Geothermal Frequently Asked Questions
Q: What is a geothermal heat pump?
A: A geothermal or “ground-source” heat pump is an electrically-powered device that uses the natural heat storage ability of the earth and/or the earth’s groundwater to heat and cool your home or business at very high efficiencies.
Q: How is heat transferred between the earth and the home?
A: The earth has the ability to absorb and store heat energy. To use that stored energy, heat is extracted from the earth through a liquid medium (water or an anti-freeze solution) circulated in the ground via open or closed earth loops and is transferred to the heat pump heat exchanger. There, the heat is used to heat your home. In the summer, the process is reversed and indoor heat is extracted from your home and transferred to the earth through the liquid circulating in the loops underground.
Q: Do I need separate ground loops for heating and cooling?
A: No, the same loop works for both. When changing from heating to cooling, or vise versa, the flow of heat is reversed by a mechanism inside the unit.
Q: What is a closed-loop system?
A: The term “closed loop” is used to describe a geothermal heat pump system that uses a continuous loop of special buried plastic pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which water or an anti-freeze solution (if you live in colder climates) is circulated. Unlike an open-loop system that consumes water from a well, a closed-loop system recirculates its heat-transferring solution in a pressurized pipe.
Q: Where can this loop be located?
A: That depends on land availability and terrain. Closed-loops are trenched horizontally in yards adjacent to the home if the yard is large enough. Or, for smaller yards, the loops can be installed vertically using a drill rig, much like a water well installation.
Q: How long will the loop pipe last?
A: Properly installed, these pipes will last over 50 years.
Q: Will an earth loop affect my lawn or landscape?
A: No, research has proven that loops have no adverse effect on grass, trees or shrubs. Most horizontal loop installations use trenches about 3 feet wide or less. This, of course, will leave temporary bare areas that can be restored with grass seed or sod. Vertical loops require less space and result in minimal lawn damage.
Q: I have a pond near my home. Can I put a loop in it?
A: Yes, if it’s deep enough and large enough. A minimum of 8-10 feet in depth at its lowest level during the year is needed for a pond to be useable. Generally, a minimum of 1/2-acre pond is required to provide adequate surface area for heat transfer.
Q: What is an open-loop system?
A: The term “open loop” is commonly used to describe a geothermal heat pump system that uses groundwater from a conventional well as a heat source in winter and a heat sink in summer. The groundwater is pumped through the heat pump where heat is extracted (in winter) or rejected (in summer), then the uncontaminated water is disposed of in an appropriate manner. Since groundwater is a relatively constant temperature year-round, it is an excellent heat source/heat sink for a geothermal system.
Q: Can a geothermal heat pump also heat water for my home?
A: Yes, using a hot water generator (HWG), some types of geothermal heat pumps can save you up to 50% on your water-heating bill by pre-heating tank water. The HWG is a factory-installed option.
Q: Can a geothermal heat pump be added to my fossil fuel (gas, oil, propane) furnace?
A: Split systems can easily be added to existing furnaces for those wishing to have a dual-fuel system. Use the heat pump as the main heating source and a furnace as a supplement in extremely cold weather if additional heat is needed.
Q: I have ductwork, but will it work with this system?
A: In most circumstances, yes. Your installing contractor should be able to determine ductwork requirements and any minor modifications, if needed.
Q: What does a system like this cost?
A: A geothermal system for the typical home will cost more than if you bought a conventional central air conditioning system. But you wouldn’t be comparing “apples to apples.” To get an accurate comparison of costs you need to consider the following:
- Payback, or how long it takes to recover the difference in costs between the two systems using energy savings. Payback for most geothermal heat pump systems runs three to five years.
- Federal, state and local tax credits / incentives will significantly reduce the upfront cost of installing a geothermal system.
- Energy efficiency of the two systems. To get an accurate picture, make sure efficiency claims are substantiated. Your lifestyle and how well your home is insulated affect how economical a system will be, too.
- Total operating savings from heating, cooling and domestic hot water must be combined to get an accurate picture of total energy savings.
- Energy costs and availability, both present and future.
- Maintenance costs and system reliability.
- System lifespan.
Q: Can I get a tax credit for installing a geothermal system?
A: Yes, up to 30% of the total investment for all ground loop or ground water geothermal heat pump installations. This includes the cost of all labor, equipment and landscaping accompanying your geothermal install.
Q: Can I use a heat pump for radiant floor heating (warm floors)?
A: Yes, water-to-water heat pumps heat water instead of air. The principle is the same as far as loop piping is concerned. Warm water is circulated through the floor to heat the home.