GEOTHERMAL FAQ
Table of Contents
General FAQ
What is Geothermal Heating?
Geothermal heating is a method of heating a structure that uses a ground source heat pump to remove heat from the earth and put it into your home. The systems are many times more efficient at space conditioning than conventional systems, and are saving regular households thousands of dollars per year on heating costs. These systems can be residential or commercial, and can work in almost any climate and soil type for both heating and cooling.
How efficient is a geothermal ground source heating system?
Geothermal ground source heating systems are the most efficient heating and cooling systems available today. The heat energy they deliver already exists and they just need to move it into the home. For every one unit of electricity the heat pump consumes it can deliver 3 to 4 times that amount of heat energy. This works out to be 300% to 400% operational efficiency. For cooling, they are 20-40% more efficient than air conditioners which are simply air source heat pumps.
What about comfort?
It will depend on the distribution system you choose to install. Radiant Heat systems provide even space heating to make rooms very comfortable, and are becoming the heating system of choice. Geothermal heating can also use a forced air system to deliver the heat. Warm air (90°-105° F) is circulated in higher volumes through the duct system, which warms the building more thoroughly, providing even heat without hot or cold spots, or the cold air blasts that are common with fuel furnaces.
Can these systems cool also?
Yes, the very same system can provide heating and cooling. The cooling works better if the distribution is forced air rather than a radiant floor. In order to effectively meet a cooling load we need to be able to remove excess humidity from the air and only forced air systems can do that. In dry climates radiant floor systems can be used to some effect at cooling a space but it should not be thought of as air conditioning.
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System FAQ
How does 40° Fahrenheit water from the ground provide heat?
A heat pump extracts the heat with a refrigeration process. It is the very same process that is used in your refrigerator or air conditioner only back wards. If you understand how air conditioning works then you understand how we can use 40° water to make 120° water.
How noisy is a GSHP?
Ground source heat pumps are relatively quiet because most use scroll type compressors which are known for their quiet operation. Each manufacture has different methods of reducing vibrations and insulating the cabinet to further reduce noise. The installation should also be done to minimize noise by properly securing piping and or using non ridged connections that will not transfer vibrations into the pipes.
How much maintenance is required?
Very little compared to conventional systems. If the distribution is air then filters would need to be changed. Heat pumps do not burn anything so most of the associated problems and maintenance required of boilers and furnaces is not an issue. Open loop systems that use ground water directly through the heat exchanger may need descaling every few years. Closed loop systems that circulate an antifreeze solution should be tested to ensure the quality of the antifreeze each season.
How much space does a GSHP take up?
A majority of the ground loop system is installed underground, and the heat pump itself is about the same size as a standard heating and cooling unit.
What is the life of my GSHP?
GSHP’s are as durable and reliable as a conventional heat system and if properly installed will provide decades of operation. The heat pumps themselves have factory warranties up to ten years and are expected to have a service life of 25 to 30 years. The earth loops are made of poly pipe that can last several hundred years.
How safe is a GSHP unit?
The GSHP systems are very safe and protected. There is nothing burned, so there is no flammable fuel or toxic fumes anywhere. There is no potential for deadly and orderless carbon monoxide to fill your home while you sleep.
Can a GSHP provide domestic hot water also?
Yes it can! Using a desuperheater, you can turn the waste heat from the system into hot water. In the summer when the system is in cooling mode, the excess heat goes straight to heating hot water. In the winter when it is in heating mode, only a portion of the water is heated. Desuperheaters are standard on some heat pumps, optional on others, and can also be bought separately.
Can a GSHP provide domestic hot water also?
Yes it can! Using a desuperheater, you can turn the waste heat from the system into hot water. In the summer when the system is in cooling mode, the excess heat goes straight to heating hot water. In the winter when it is in heating mode, only a portion of the water is heated. Desuperheaters are standard on some heat pumps, optional on others, and can also be bought separately.
What is the max temperature a GSHP can produce?
The max is recommended temp to run a heat pump is 120° F. While many heat pumps can produce temperatures hotter than that, (up to 140 F) is is not recommended as it is hard on the compressors to produce pressures/temperatures that high. The efficiency of the operation is also severely reduced at temperatures hotter than 120 F. In fact if you want really efficient operation you should keep the temperature set point as low as possible to satisfy the load.
COSTS FAQ
How expensive are these systems?
The initial expense is generally greater than conventional systems but there are some exceptions to that. If the site has easy and sufficient access to ground water then the cost of the ground loop is greatly reduced. Each site is different but in the best-case scenarios the total system installation would cost the same as a conventional heating system using a furnace or boiler. In all cases the geothermal system will begin paying off its installation costs the moment you start using it. All other conventional systems will consume energy and money for their entire service life.
How is the money saved?
Geothermal heating saves you tons of money all year in operating and maintenance costs. You can provide the same heating you are used to for a fraction of the cost. The initial investment can be made up in these savings in as little as three years. Until then there is actually usually a positive cash flow, because the savings from the system exceeds the payments on the system. Then after it is paid off, the savings are gigantic.
How much can I save?
Ground source heat pumps deliver heat at 400% efficiency. They operate on electricity. Depending on what we are comparing it to, you can expect savings of up to 70% on what you would pay for conventional heat. Consider the average Montana home that is using propane as it primary means of heat will spend $2000 per year for domestic heat and heat for the domestic water. A geothermal system could provide that same energy for $600. That’s a savings of $1,400 every year! Easily enough for the payment to pay off the system.
Are there any state or federal incentives for installing a GSHP system?
Yes, there are many incentives available on both the state and federal levels. The current federal tax credit is 30% of the cost of the installed system. You can visit DSIRE to see if your state has any incentives.
Installation and Building FAQ
Where can these systems be installed?
Virtually anywhere. There are several ways to tap into the earth’s energy and a site specific review will determine the most cost effective way.
Can geothermal heating be used with forced air distribution?
Yes, but the duct work should be sized for a larger volume of air than would be used with a furnace. The lower temperature air that will be distributed to the room needs to be delivered in greater quantities than the high temp air a furnace provides. The comfort level of geothermal systems exceeds that of a furnace because the air is not as dry, there is more air exchange and fewer cold or hot spots in the home.
How far are the boreholes in a vertical loop system spaced?
All the boreholes in a vertical loop system are typically spaced about 10-15 feet apart, which also depends on the terrain and soil composition.
Can Geothermal Heat Pumps be installed in retrofit situations?
Yes, but some structures and locations are more ideal than others. The existing distribution will need to be able to be compatible with the lower temperatures of geothermal (120 Fahrenheit). Radiant floors are an ideal distribution system. High temp radiators are not ideal and some type of supplemental heat would be required.
How far apart are the trenches spaced in a horizontal loop system?
In a horizontal loop system, the trenches are usually spaced 6-10 feet apart, depending on the terrain and soil characteristics.
How is the system sized?
The systems are generally sized based off the heating load needed in the house and the climate of the area. But many considerations come into play in determining that size. Soil composition, structure size and layout, area, and land size all play a role in determining the size of an individual system.
ENVIRONMENT & CLIMATE FAQ
Is geothermal heating considered renewable energy?
Absolutely! It uses the heat that is from the sun and stored in the earth to heat your home. It is considered clean, green and renewable energy. There is no fossil fuels burned, combustion, or dependency on a finite fuel source. It only uses electricity to run the heat pump, and that also can come from many different renewable sources as our electric grid starts to change and develop.
Can a geothermal heating system still work in climates with frozen soil?
Absolutely! That is the exact environment where we are thriving in. Winters in Montana are very harsh, and the soil is probably frozen for over half of the year. But because the ground loops are installed below the freeze line (usually 6-8 feet in depth, depending on soil type), the changing temperatures above ground do not effect the heating capabilities.
Do GSHPs protect the environment?
Yes they do. The GSHP system runs very efficiently to provide climate control from renewable energy, which lowers emissions. It does not burn fossil fuels and is a completely enclosed system, so no dangerous gases are released into your home or the environment. All the refrigeration systems are factory-sealed, so they seldom or never have to be recharged, which also protects our environment.
Can I use the GSHP for snow melt capabilities?
Yes, the geothermal systems can be effectively used to provide the heat for snow melt systems.
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