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  Frequently Asked Questions
What is a Geothermal Heat Pump? A geothermal heat pump is an electrically powered device that uses earth’s natural heat and/or groundwater to heat and cool your home or business. How does it work? A geothermal heat pump’s scientific principle is the same as a refrigerator. Using this principle, geothermal heat pumps remove the earth’s fairly consistent temperature that is stored a few feet beneath the Earth’s surface and/or groundwater, and transfers it to your home to provide extremely efficient heating and cooling. In the winter, a fluid circulating through the underground pipes absorbs the earth’s heat and carries it into the home. It is then passed on to the geothermal heat pump inside the home where electrically driven compressors and heat exchangers in a vapor compression cycle concentrates the earth’s thermal energy to release it into the interior space for warmth. In a typical air system, duct fans distribute the heat to various rooms. With a Hydronic heating system, warm water is circulated throughout the building. In the summer, the process is reversed: Heat is extracted from the air in the home and passed on through the heat pump to the same ground loops. The fluid in the ground loops then carries the heat back into the earth. Only a small portion of external energy is needed: a small amount of electricity to run the heat pump, ground loop pump and distribution fan or pump. Is geothermal heating and cooling new? In fact, the basic technology has been around for more than 50 years. Many individuals and businesses have been enjoying the benefits of using the earth’s heat for much of that time. In just recent years, has the installation, material used, electronic control systems, and efficiencies of the compressors, heat pumps and other equipment been dramatically improved. There are now more than one million installations in the US today. What are the components of a geothermal heat-pump system? The three main parts are the heat pump unit, liquid heat exchanger medium and ductwork. Are all geothermal heat pumps alike? The most used heat pumps are fairly similar, but there are a lot out there to fit different needs. Most geothermal heat pumps are designed for air conditioning and heating, but there are some specifically for winter heating. There are heat pumps designed for higher temperatures for open-looped systems, and others with lower temperatures with a closed-loop system. There are units that combine the blower compressor, heat exchanger and coil in one single cabinet. Split systems utilize the existing blowers by just adding the coil to a forced-air furnace. Talk with one of Thermterra’s certified contractors to find the perfect fit for your needs. Will I have to add insulation to my home if I install one of these systems? Whether or not your home is well insulated, geothermal heat pumps will reduce your heating and cooling costs. However, insulating and weatherizing your home can reduce heating cost that much more. Can a GeoExcel heat pump heat water for my home? Yes. A desuperheater can be added to the unit to do that task. It is a heat exchanger that uses superheated gases from the heat pump’s compressor to heat water. This hot water then circulates through a pipe to the water heater tank. In the summer, when your system is in the cooling mode, the desuperheater uses the excess heat that would otherwise be put back into the ground for hot water. This can be a savings of 50% off of your water heating bill. If the geothermal unit isn’t running frequently, therefore the desuperheater isn’t producing enough; a conventional water heater meets the demands of the household hot water. Is a GeoExcel heat pump difficult to install? Most units are easy to install, especially if you are replacing an existing forced-air system. They do not have restricted areas where you can’t install them like fossil fuel furnaces do. When installing ductwork, the difficulty of it will vary, depending on the contractor. To find Thermterra’s certified dealers, please contact us at 218-724-5555. Can a GeoExcel heat pump be added to my fossil fuel furnace? Yes, you could get a split system, which is easily installed to an existing furnace. The heat pump would be the main source of heat, but in the extremely cold weather, the furnace could be used as backup heat. I have ductwork, but will it work with this system? Yes, it will. Minor adjustments might be needed, but your installer will be able to determine the ductwork requirements for you. Do I need to increase the size of my electrical service? Geothermal heat pumps do not require a lot of electrical amps to run. For most people, your existing service is just fine. Your contractor will be able to see whether or not you need to change your electrical service. Should I buy a GeoExcel heat pump large enough to heat my home with no alternative heating? You will be able to receive a heat loss/ heat gain through your contractor, to help you decide which heat pump would work best for your situation. Geothermal heat pumps are sized to meet your cooling requirements. Depending on your heating needs, a geothermal heat pump will supply 80 to 100% of your heating load. Sizing your heat pump to your exact heating needs might lower your energy costs insignificantly, but usually not enough to offset the added cost of buying a larger heat pump. There also have been dehumidification problems in the cooling mode with an oversized unit, causing discomfort in the summer. Do GeoExcel heat pumps have outdoor units? No, they are located inside your home, usually in the basement, garage or crawl space, which also extends the lifetime of the equipment greatly. What types of loops are available? There are two main types: open and closed. Open loops are submersed in ground water, and closed loops are either installed horizontally or vertically in the ground. Which option is best, open or closed? There is essentially no difference in the operating cost or efficiency between the two. Whether or not an open loop would work for you will depend on if you have a groundwater supply and means of disposal. If you do not, either a horizontal or vertical closed loop system would be your best choice. Over a period of years, a closed loop system will require less maintenance because it is sealed and pressurized, eliminating the possible mineral and iron buildups.
CLOSED LOOP SYSTEMS: A closed-loop system is a continuous loop of pipe acting as a heat exchanger that re-circulates its heat through the heat pump inside the home using antifreeze solution within a sealed, underground pressurized piping system. Is there just one way to install a closed loop system? No, you can either do a horizontal ground closed loop or vertical ground closed loop. A horizontal ground closed loop is usually the most cost effective way to install, if there is enough yard space for trenches. It is best for a new home, but the option of horizontal boring is possible. Workers use trenchers or backhoes to dig the trenches six to eight feet below surface, and then lay a series of parallel plastic pipes down. The average length of a horizontal loop is 800 feet long per ton of heating and cooling capacity. The other option is a vertical ground closed loop system. This is ideal for homes with limited amount of yard space. A contractor bores vertical holes in the ground 150 to 450 feet deep. Each hole contains a single loop of pipe with a u bend at the bottom. After a pipe has been inserted, the hole is then backfilled or grouted. Each vertical pipe is then connected to a horizontal pipe, which is also concealed underground. The horizontal pope then carries fluid in a closed system to and from the geothermal system. Vertical loops are generally more expensive to install, but require less piping than horizontal loops because the earth deeper down is cooler in summer and warmer in winter. Where can this loop be located? This depends on the amount of land available and terrain. Most closed loops are trenched horizontally in yards that border the home. But any area near the home or business with suitable soil conditions and sufficient amount of square footage will work. How deep and long will my trenches be? Trenches are normally four to six feet deep and up to 400 ft long. This depends on how many pipes are in a trench. How long will the loops be? This depends on a number of factors: the type of loop configuration used, a home’s heating and air conditioning load, soil conditions, local climate and landscaping. Larger homes with a larger space conditioning requirements generally need larger loops than smaller homes. Homes in climates where temperatures are extreme also generally require larger loops. A heat loss/heat gain analysis is done by Thermterra before the loop is installed. How is the pipe sections of the loop jointed? By heat fusing the two ends together using a fusion kit, which is available for rental or purchase from Thermterra. Once the two pipes are fused together, they form a joint stronger than the original pipe. How long will the loop pipe last? The loop is made of a material that is extraordinarily durable but allows heat to pass through efficiently. When the certified installers heat fuse sections of the pipes together, it makes the connections stronger than the loop itself. Loop manufacturers offer a lifetime warranty on their high-density polyethylene loop.
Will ground loops affect my lawn or landscape? Can I reclaim heat from my septic system disposal field? No, a ground loop will reach temperatures below freezing during extreme conditions and may freeze your septic system such usage is banned in many areas. If the loop falls below freezing, will it hurt the system? No. The antifreeze solution in the loop will keep it from freezing down to about 10° F. Three types of antifreeze solution are acceptable: propylene glycol, calcium chloride and methyl alcohol. Thermterra stocks the propylene glycol. Can I install the loops myself? This is not recommended. Non-professional installations may result in less than optimum system performance.
OPEN LOOP SYSTEMS: “Open-loop” is often referred to a geothermal system that uses groundwater from a conventional well as a heat source. The ground water is pumped into the heat pump to extract the heat, and then the water is disposed. Since groundwater is fairly constant year around, it is an ideal heat source. Is there only one way to install an open loop system? Yes. This set up is used less frequently, but may be more cost effective if ground water is plentiful. They are the simplest to install and have been used successfully for decades in areas where local laws permit. In this system, ground water from an aquifer is piped directly from the well to the building, where it transfers its heat to a heat pump. After it leaves the building, the water is pumped back into the same aquifer which is a second well or a drain tile. What do I do with the discharge water? There are various ways to dispose of water. The open discharge is the easiest and most economical. Open discharge releases the water into any stream, river, lake, pond, ditch or drainage tile that can handle that capacity. The return well is a second well bore that returns the water to the ground aquifer. Make sure the return well is tested to the capacity before you use it as a return. How much groundwater does an open-loop system need? This depends on the size of the unit, and manufacturer’s specifications. The water requirement of a specific model is usually in gallons per minute (gpm). Either the certified dealer or Thermterra staff can give you your specific requirement. What problems can be caused by poor water quality? Poor water quality can be a serious issue. Always make sure you get your water tested which can be done by a certified installer for hardness, acidity and iron content before installing an open loop system. You also want to be sure there will be no organic matter or excessive particles that will flow through the loops; this can clog up the heat pump, making it not work. Mineral deposits can also build up inside the heat pump exchanger. You can easily remove the build up with mild acid solution. But impurities like iron can eventually clog a return well. If your water has a high iron count, make sure that the discharged water is not exposed before it is injected into a return well. Do open-loop systems cause environmental damage? No, they are pollution free. Water goes in, water goes out with no noxious waste added whatsoever. The only change in the water returned to the environment is the slight change in temperature. Are there any laws that apply to open-loop installations? In some regions, the installation may be subject to local regulations, contracts or licensing requirements. You will want to check with your specific area. I have a pond near my home. Can I put a loop in it? Yes, if you have a deep enough and large enough pond that has a minimum of 6 feet in depth at its lowest level during the year. Copper, polyethylene or polybutylene pipe can be used.
GEOTHERMAL HEAT PUMPS: WHAT ARE THE MAJOR BENEFITS? Using a typical 3 ton system for over a 20 year lifespan is equivalent of converting about 58,700 cars to zero-emission vehicles or planting more than 120,000 acres of trees. A geothermal heat pump is protected from the harsh weather by being located indoors, most commonly, the attic or basement, because they are compact and there is no need to use the outdoor air like a conventional system requires. Also, they are so quiet, that a homeowner doesn’t even realize it is on. Since a geothermal system draws a fairly consistent and moderate heat from the ground, it doesn’t have to use as much energy, therefore, help keeping the electricity bills lower. How efficient is a GeoExcel heat pump? GeoExcel heat pumps are 3 to 5 times as efficient compared to the most efficient fossil fuel furnaces on the market. Since they are only moving the heat that already exists, they provide three units of energy for every one unit used to power the heat pump system. How much does a system like this cost? The upfront cost of a geothermal system in a typical home will cost more than if you were to purchase a furnace and central air-conditioning system. But to get an accurate comparison you would have to take into account the payback period, energy efficiency, total operating savings from heating, cooling and domestic hot water, energy costs and availability, and maintenance costs and system reliability. Thermterra can give you an estimate by calling 218-724-5555. How long will it take for my system to pay for itself? This answer depends on what it would have cost you if you were to use another heating and cooling system, and how much lower your bills will be when you are using the geothermal system. Thermterra takes pride in providing free cost analysis’ to our contractors which would tell you about how much it will cost you to operate the system, and how long it will take for the savings to cover the cost of the system completely. What about Comfort? A geothermal system has very steady, even heating and cooling. This is because the warm air is moved in a slight higher volume than a furnace does, which saturates the home with warmth more evenly. This evens out the hot and cold spots in your home. There is no blast of cold air that comes with fossil fuel furnaces. You also have that peace of mind knowing you are being environmentally responsible. Can I get a tax credit for installing this system? Yes. Currently there is a 30% federal residential energy tax credit available for installing a geothermal system as well as a 10% commercial federal tax credit. For further details go to www.dsireusa.org. Are there any financial incentives for installing a geothermal system? Yes. To see a comprehensive listing of incentives for renewable energy systems, go to www.dsireusa.org. You also might want to consider calling your state energy office or local utility for more information. Many of the utility power companies are offering big rebates on geothermal installations, and a special (lower) electrical rate for geothermal heat pumps. How long is the payback period for your geothermal heat pump system? Your certified installer is able to get to you an energy audit that would provide the estimated payback period. You must know how much per year you would be saving with a geothermal system, and the difference between that and a conventional heating system and central air conditioner. If a home has a ceiling cable heat or baseboard heat, do air ducts need to be installed? This is not always the only option, but it is desirable to install geothermal heat pump room units. The ceiling cable and baseboards can then be used as secondary heat. If I want to know more about geothermal heat pumps, whom should I contact?
There are many people you can contact: |
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