Frequently Asked Questions
- How does a geothermal heating & cooling system work?
- What makes a geothermal system different from ordinary systems?
- What is a geothermal heat pump?
- How deep are the geothermal ground loops buried?
- How much does a geothermal system cost?
- What the impact on my property?
- If the geo system runs on electricity, what happens if power goes out?
- Will the geothermal system increase my electric usage?
- How long does an installation take?
- Do geothermal systems require much maintenance?
- What's the return on investment (ROI) generally?
1. How does a geothermal heating & cooling system work?
Outdoor temperatures fluctuate with the changing seasons but underground temperatures don’t. Just a few 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” thermal 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 home. In summer, the system reverses, pulling heat from the home, carrying it through the earth loop and depositing it in the cooler earth.
Geothermal heating and cooling systems are the most efficient and environmentally friendly systems on the market today. These systems work differently than conventional systems by taking advantage of the sun’s solar energy that is absorbed and stored by the earth. Once you are below the frost line the ground maintains a fairly constant temperature, approximately the average annual outside air temperature for the region. In most systems, a water solution circulates in pipes in the ground to carry thermal energy to the heat pump in the winter for heating and moves heat from the house into the ground in the summer. Since so much of this energy actually comes from the ground, geothermal systems use relatively little electricity to convert this energy to comfortable temperatures inside a building year round.↑ Top
2. What makes a geothermal system different from ordinary systems?
A conventional heating system burns fossil fuels (e.g., natural gas, propane, oil, etc.) for space heating and a separate air conditioning system for cooling. Geothermal heating and cooling systems have one geothermal heat pump which both heats and cools leveraging the constant temperature of the ground to produce maximum efficiencies in both heating and cooling modes. So instead of burning fossil fuels to generate heat and expelling heat from the house in the summer into hot air outside, a geothermal system transfers heat to and from the earth to provide a more efficient, affordable and environmentally friendly method of heating and cooling your home. Typically, electric power is used only to operate the unit’s fan, compressor and pump.↑ Top
3. What is a geothermal heat pump?
The term heat pump technically describes all electric refrigeration systems, like your kitchen refrigerator or your car’s AC, but for the purposes of space heating the term heat pump typically includes the ability to reverse the cycle from heating to cooling. A geothermal heat pump is capable of leveraging the relatively constant temperature of the ground to provide renewable heat and extremely efficient air conditioning for homes and businesses. A fluid circulates thermal energy to and from the building and the geothermal heat pump is designed to very efficiently raise the temperature in the winter or deposit the buildings thermal energy to the ground in the summer. Geothermal heat pumps are the most efficient heating systems available on very cold days and the same system can reverse to provide the most efficient air conditioning on hot days. Most geothermal heat pumps can also be equipped to heat domestic water very efficiently.↑ Top
4. How deep are the geothermal ground loops buried?
Horizontal closed loop systems in Upstate New York are buried in the 6 to 8 foot range over a relatively large area. This can be configured in a series of long relatively narrow trenches or a larger rectangular excavations with a network of loops similar to a pattern you might see for a radiant floor system.
Vertical closed loop systems are often hundreds of feet down – so 300 to 450 feet are common for a single geothermal borehole. Larger homes and commercial buildings will have more than one vertical loop to ensure there is sufficient thermal exchange with the ground. Most single family homes typically have one or two boreholes, while a large commercial building might have over 100 boreholes, each borehole 400 feet deep on 20 foot centers (spacing), concealed under a large parking lot.
BTW- for scale a 400 foot borehole is a depth similar to the height of a 40 story building!↑ Top
5. How much does a geothermal system cost?
The initial investment for a geothermal system is greater than that of a conventional system. However, when you consider the operating costs of a geothermal (heating, cooling, and water heating) system, energy savings quickly offset the initial difference in purchase price. In addition, you can also expect an installation charge for any electrical work, ductwork, water hook-up, and other provisions or adaptations to your home that are required.↑ Top
6. What the impact on my property?
The majority of geothermal heat pump installations done by Aztech are closed loop system with buried pipes below the ground in your yard (i.e., horizontal ground loop) or vertically drilled systems with the geothermal pipes inserted down the borehole. Horizontal systems take up an area similar to the conditioned area of the home/building which needs to be excavated, pipes installed and backfilled back to “rough grade”. This works best if you have an area near the home/building that is not a manicured lawn or is a new construction project where landscaping will take place as a part of the larger project. Vertical systems will have less impact since most of the thermal exchange happens vertically – straight down. On a vertically drilled systems there is still heavy equipment and some amount of excavation back to the building to bring the pipes to through the foundation below grade.↑ Top
7. If the geo system runs on electricity, what happens if power goes out?
Just for perspective, all modern central heating and air conditioning systems rely on electricity to run; and so does a geothermal system. Even some wood stoves have an electric blower! So when the power goes out, so does your heat or AC – unless you have a back-up generator. A geothermal system can be run on a back-up electric generator and we can help make sure it’s sized properly.↑ Top
8. Will the geothermal system increase my electric usage?
Your electric bill will increase but cost only a portion of what you were paying for your previous heating system.↑ Top
9. How long does an installation take?
It is largely house specific but on average 2-3 days for the interior portion and 2-4 days for the exterior portion. Usually the interior and exterior will coincide with each other. If whole house ductwork needs to be installed it could take 2-4 weeks depending on the size of the home and ease of installation.↑ Top
10. Do geothermal systems require much maintenance?
No. The geothermal parts of your heating and cooling system are virtually maintenance free. Most of the geothermal heat pumps we install are factory sealed refrigeration systems – very much like a kitchen refrigerator. When installed properly, the buried loop will last for generations simply circulating a water solution at low pressure. All the mechanical equipment is safe indoors, protected from weather conditions. Geothermal heat pumps typically switch from heating to cooling automatically and most only require an air filter to be changed a couple times a year. Many of our customers have one of our technicians come out once a year to check things over, while other customers do the routine maintenance themselves.↑ Top
11. What's the return on investment (ROI) generally?
Geothermal heat pump systems are recognized as the most efficient heating and cooling systems available, but they have a higher first cost (installation cost) than many other alternatives. For a typical single family home without access to natural gas, the additional cost to upgrade to a geothermal system will have returns on the 5% to 8% annually at today energy prices for propane and heating oil. So if the system cost $10K more to install, it would be like getting 5% to 8% return annually on a $10K investment – which is pretty good these days!
For businesses the range is greater depending on your tax status and a number of other factors. The best returns are much higher.↑ Top