A Ground Source System is an electrically powered system that taps the natural heat stored in the earth to heat in the winter and to cool your home or business in the summer. In addition, this system can be used to heat your water.

Q: What are the components of a Ground Source System?

There are three: the heat pump unit, the liquid heat exchanger medium (the closed loop pipe system) and the air delivery system (ductwork).

Q: How does it work?

The system simply moves heat energy from one place to another. Your refrigerator works on the same scientific principle. Just as it removes heat from your food to the surrounding air, in the summer a Ground Source System removes heat from your home and transfers it to the ground. In the winter, the system removes heat stored in the earth and transfers it to your home.

Q: Is the earth really a solar collector?

Yes, it is the original solar collector. In the day it absorbs heat from the sun, even on cloudy days. At night it radiates that heat back out into the night sky.

Q: How is heat transferred between the earth and my home?

Heat is extracted from the earth by water circulated through underground pipes and pumped to a heating and cooling appliance called a water source heat pump. The heat is further concentrated by a compressor and used to heat the air of your home. In summer, the process is reversed. Indoor heat is extracted from your home and transferred to the earth through the liquid. As a side benefit, this system will also heat your water at no extra cost.

Q: How large are the indoor components of the system?

The system used for most residences is no larger than (and often smaller than) a typical gas furnace.

Q: Does one system both heat and cool?

Yes. One of the things that makes a Ground Source System versatile is its ability to be a combination heating and cooling system. You can change from one mode to another with a simple flick of a switch on your indoor thermostat.

Q: How efficient is a Ground Source System?

They are more than three times as efficient as the most efficient fossil fuel furnace. Instead of burning a combustible fuel to make heat, the system simply moves heat that already exists. By doing that, they provide three units of energy for every one unit used to power the system.

Q: How can homeowners afford the investment?

The investment requirement for a Ground Source System, unlike other projects, produces a very attractive annual savings and payback, and increases the market value of the home. A typical payback period is three to five years. Your dealer/installer and your local utility will be able to advise you about the availability of special financing.

Q: What other costs exist besides the Ground Source System?

You can expect an installation charge for any electrical work, ductwork, water hookup and other provisions or adaptations to your home that are required.

Q: What is a closed-loop system?

The term "closed-loop" is used to describe the Ground Source System which uses a continuous loop of special buried 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 antifreeze solution is circulated.

Q: Where are these loops located?

The closed-loops are laid in trenches, horizontally, or in wells, vertically. Both are placed in yards adjacent to the building. Any area near a home or business with appropriate soil conditions and adequate square footage will work. The design used depends on available space, but neither design is superior to the other.

Q: Will I need separate ground loops for heating and cooling?

No. The same loops work for both. Changing from heating to cooling, or vice versa, is very simple. The flow of heat is simply reversed with the flick of a switch.

Q: Are Ground Source Systems difficult to install?

Most units are easy to install, especially when they are replacing another forced-air system. Ductwork must be installed in homes that don't have an existing air distribution system. This cost of installing ductwork can be assessed by your dealer/installer.

Q: Can I install an earth loop myself?

It's not recommended. In addition to thermal fusion of the pipe, drilling and trenching are procedures best handled by licensed professionals. Nonprofessional installations may result in less than optimum performance, which could cancel out the anticipated savings and may void manufacturer's warranty.

Q: How long should the pipe be?

The length and diameter are determined by the size of the Ground Source System, climate, soil type, depth and operating cycle pattern for each installation.

Q: How long will loop pipe last?

Polyethylene or polybutyalene pipe when properly installed will last over 50 years. (The International Ground Source Heat Pump Association recommends the minimum cell classification number acceptable for polyethylene pipe is PE355434C or PE345434C when tested under ASTM 3350).

Q: How effective is this underground system?

The buried pipe, or ground loop, is the most recent technical advancement in heat pump technology. The idea to bury pipe in the ground to gather heat energy began in the 1940's. Only recently, however, have new heat pump designs and improved pipe materials been combined to make Ground Source Systems the most efficient heating and cooling systems available.

Q: Will my existing ductwork function with this system?

Yes, in most cases. Your dealer/installer will be able to determine ductwork requirements and minor modifications needed, if any.

Q: How long does it take to install a horizontal system?

Time is dependent on soil conditions, length and depth of pipe and the equipment required. A typical installation can be completed in one to three days.

Q: What if there's not enough room for the loop?

Ground Source Systems can also be vertical. Holes are bored to about 120-180 feet per ton of heat pump capacity. U-shaped loops of pipe are inserted in the hole. The holes are then backfilled with a sealing solution.

Q: How long does it take to install a vertical system?

With the vertical installation, time varies with conditions at the site, such as type and depth of the overburden, type and hardness of the bedrock and presence of aquifers. Typical drilling times are one to two days and the total installation can usually be accomplished in three days.

Q: What are the advantages and disadvantages of the horizontal -vs- vertical installations?

Horizontals are simpler, require lower cost equipment and less training of installers. However, they require longer lengths of pipe due to variations in soil temperature and moisture content, and installations can be affected more by extensive rainy weather. A much larger area is required. Extensive hard rock may dictate a vertical installation. Verticals require more highly trained operators for the drilling machines, but less pipe length is required which offsets much of the higher drilling cost. Vertical installations, however, are ideal where land area is limited.

Q: How can I be sure the pipe is installed properly?

Use a reputable contractor. Don't be afraid to ask for references. Reputable dealers and loop installers will be happy to give names and numbers for you to call and confirm their capabilities. Also, check with your utility company representative.

Q: Will an underground loop affect my lawn or landscape?

No. Research has proven that loops have no adverse affect on grass, trees or shrubs. Most horizontal loop installations use trenches about six inches wide. Temporary bare areas can be restored with grass seed or sod. Vertical loops require little space and result in no significant lawn damage.

Q: Does the system have outdoor units?

No. The equipment goes inside your home, in the basement, garage or crawl space. Because they are housed indoors, the life-span of the compressor and major components are greatly extended, most lasting 20 years or more, and you won't have the noise or servicing problems you have with an outdoor unit.

Q: My yard contains many shade trees. Will this affect the ground temperature and my ability to use it as an energy source?

Not at all.

Q: Do freezing soil conditions create any problems?

This is not a problem if the system is properly designed. The three to four feet depth allows the sun to melt the frozen soil. Adequate length-per-ton capacity prevents objectionable soil movement.

Q: What changes in performance can be expected at freezing operating conditions?

A drop in soil temperature from 40F to 30F results in a loss of capacity and efficiency of about 10 percent. At 30F, the latent heat of the freezing of the moisture in the soil adds considerably to the capacity of the system.

Q: Will I have to add insulation to my home for one of these system?

No, the system will reduce your heating and cooling costs regardless of how well your home is insulated. However, insulating and weatherizing are key factors in gaining the most savings from any type of heating and cooling system.

Q: Does the system help in the new, small, highly insulated homes?

Yes. As energy costs increase, the savings will be increasingly more significant. The payback and return on investment will be about the same as for larger systems.

Q: Can a Ground Source System also heat my water?

Yes. Using what is called a desuperheater, some types of systems can save you up to 50% on your water heating bill by preheating tank water.

Q: Can a Ground Source System be added to my fossil fuel furnace?

Yes. These "split systems" can be easily added to existing furnace for those wishing to have a dual-fuel heating system. Dual-fuel systems use the Ground Source System as the main heating source, and a fossil fuel furnace as a supplement in extremely cold weather should additional heat be needed.

Q: Is a Ground Source System, which is large enough to handle my total heating needs, advisable?

Your dealer/installer should provide a heating and cooling load calculation to guide your equipment selection. Ground Source Systems are sized to meet all your cooling needs and 80-100% of your design heating load. Sizing the system to handle your entire heating needs may result in slightly lower heating costs, but the savings may not offset the added cost of the larger system.

Q: How comfortable can the system make my home?

The system moves warm air throughout your home via standard ductwork. It creates an even comfort level by moving the warm air in slightly higher volumes, and saturating the home with warmth more evenly. This eliminates hot or cold spots.

Q: Is this system compatible with the environment?

Yes. Ground Source Systems work towards the preservation of nature by minimizing present environmental problems like acid rain, air pollution and the destruction of the ozone layer.