Using a ground source (geothermal) heat pump system is a very efficient way to both heat and cool homes and businesses. We will eventually update this section with neat colorful charts and graphs to allow you to compare costs and the energy savings realized with a ground source heat pump. Until then, the following is general information concerning typical installation costs in New England.

1. A typical 2,200 to 2,500 square foot home requires a 4-ton or 5 ton ground source heat pump system.
2. Cost to complete all inside work ranges from $5,000 per ton (for a basic air duct system) to $7,000 per ton (for a more elaborate air duct & radiant floor heating system). By the way, the PEX tubing used as part of the radiant floor heating system is guaranteed for 100 years.
   1. If you want heating & air conditioning using only air ducts (no radiant floor heating), you only need the air ducts installed. This option is the least expensive option at about $5,000 per ton.
   2. If you're interested in radiant floor heating only, then you don't need air ducts installed. This option is about $6,000 per ton.
   3. If you want radiant floor heating and air conditioning, you do need the air ducts installed in addition to the radiant floor system. This option is about $7,000 per ton.
3. The complete earth coupling work (deep wells) ranges from $1,600 to $1,800 per ton.

So a 5-ton geothermal radiant floor heating system with an air duct cooling system will cost about $35,000. In addition, the cost for the earth coupling (well) will be about $8,500. The total cost for this system is $43,500. No back-up heating system is needed, however, if you lose power, the heat pump will not work.

Solar Thermal Assisted Heat Pump For Maximum Efficiency

For homes, a 3-collector solar thermal system with a 120 gallon hot water storage tank could be used both as a pre-heat for your domestic hot water, and as a pre-heat for your ground source heat pump, increasing its efficiency. The total cost for this 3-collector solar thermal system is about $10,000. You'll get a $2,000 federal solar tax credit, so figure you're really spending $8,000.

Since the ground source heat pump system and the solar thermal system will not usually supply 100% of your domestic hot water requirements, you'll need a back-up oil, gas or electric hot water heater. If using gas as a back-up to heat your domestic hot water system, then a tankless water heater is recommended. Gas water heaters need to be vented outdoors which greatly increase standby losses. Tankless water heaters eliminate all standby losses.

In summary, the total estimated installed cost for a the 5-ton geothermal heating and cooling system with a solar thermal hot water system about $55,000. This system includes radiant floor heating, air ducts for cooling and a tankless water heater.

If you're not planning to install radiant floor heating, then you'll save an estimated $10,000. The complete estimated cost for a 5-ton geothermal heating and cooling system (without radiant floor heating) with a solar thermal hot water system and a tankless water heater is about $45,000.

Geothermal Heat Pump Incentives: Rebates and Tax Credits

Eventually we'll update this section with a breakdown of geothermal or ground source heat pump incentives and rebates offered by each state. Until then, please visit www.dsireusa.org. This website offers a comprehensive list of all renewable energy and energy efficiency incentives offered in each state.

How a Ground Source (Geothermal) Heat Pump Works

The following explanation was copied from the Department of Energy's Energy Efficiency and Renewable Energy website.

Almost everywhere, the upper 10 feet of Earth's surface maintains a nearly constant temperature between 50 and 60°F (10 and 16°C). A geothermal heat pump system consists of pipes buried in the shallow ground near the building, a heat exchanger, and ductwork into the building. In winter, heat from the relatively warmer ground goes through the heat exchanger into the house. In summer, hot air from the house is pulled through the heat exchanger into the relatively cooler ground. Heat removed during the summer can be used as no-cost energy to heat water.

Geothermal heat pumps (sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps) have been in use since the late 1940s. Geothermal heat pumps (GHPs) use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly high efficiencies (300%-600%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.

While many parts of the country experience seasonal temperature extremes-from scorching heat in the summer to sub-zero cold in the winter-a few feet below the earth's surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45°F (7°C) to 75°F (21°C). Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The GHP takes advantage of this by exchanging heat with the earth through a ground heat exchanger.

As with any heat pump, geothermal and water-source heat pumps are able to heat, cool, and, if so equipped, supply the house with hot water. Some models of geothermal systems are available with two-speed compressors and variable fans for more comfort and energy savings. Relative to air-source heat pumps, they are quieter, last longer, need little maintenance, and do not depend on the temperature of the outside air.

A dual-source heat pump combines an air-source heat pump with a geothermal heat pump. These appliances combine the best of both systems. Dual-source heat pumps have higher efficiency ratings than air-source units, but are not as efficient as geothermal units. The main advantage of dual-source systems is that they cost much less to install than a single geothermal unit, and work almost as well.

Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5-10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 40,000 geothermal heat pumps installed in the United States each year.

• Types of Geothermal Heat Pump Systems
• Benefits of Geothermal Heat Pump Systems
• Selecting and Installing a Geothermal Heat Pump System

Benefits of Geothermal Heat Pump Systems

The biggest benefit of GHPs is that they use 25%-50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units of heat from the earth. According to the EPA, geothermal heat pumps can reduce energy consumption-and corresponding emissions-up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. GHPs also improve humidity control by maintaining about 50% relative indoor humidity, making GHPs very effective in humid areas.

Geothermal heat pump systems allow for design flexibility and can be installed in both new and retrofit situations. Because the hardware requires less space than that needed by conventional HVAC systems, the equipment rooms can be greatly scaled down in size, freeing space for productive use. GHP systems also provide excellent "zone" space conditioning, allowing different parts of your home to be heated or cooled to different temperatures.

Because GHP systems have relatively few moving parts, and because those parts are sheltered inside a building, they are durable and highly reliable. The underground piping often carries warranties of 25-50 years, and the heat pumps often last 20 years or more. Since they usually have no outdoor compressors, GHPs are not susceptible to vandalism. On the other hand, the components in the living space are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done on a timely basis.

Because they have no outside condensing units like air conditioners, there's no concern about noise outside the home. A two-speed GHP system is so quiet inside a house that users do not know it is operating: there are no tell-tale blasts of cold or hot air.

List of local GHP installers:

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