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How a Geothermal Heat Pump Works

Maryland homeowners have multiple options when it comes to home comfort, but geothermal heat pumps are usually the most efficient and cost-effective choice. Geothermal systems provide levels of efficiency that can't be matched by other types of home heating and cooling equipment. They also offer multiple additional benefits that make them an exceptionally good option for North Carolina climates. The following overview of geothermal heat pumps will give you an idea of how these systems work and why one might be the best type of home heating and cooling system for you.

Geothermal Heat Pumps: Operation

Geothermal heat pumps work on the same principle as air-source models: they capture heat and move it from place to place. In the summer, they move heat out of your home to provide indoor cooling. In the winter, they bring in heat from the outdoors to provide heating. What sets geothermal heat pumps apart is the source they use for acquiring and releasing heat. Unlike an air-source heat pump that uses the air around the unit, geothermal systems pull heat out of the ground or a body of water. They also use these areas as a "heat sink" where heat from inside your home can be easily dispersed during cooling operation.

Heat capture and release is accomplished using an antifreeze solution or plain water circulating through a series of pipes, called the loop system. The loop consists of a network of tubes or pipes either buried underground or submerged in a body of water. The loop pipes are placed at a depth where temperatures in the surrounding soil or water stay relatively consistent all year long, no matter how hot or cold it gets at the surface. When the system is set to provide indoor heating, the solution in the loop pulls in heat from the ground or water source. The heated solution circulates to the indoor unit of the system, where the heat pump itself uses a refrigerant-filled heat exchange coil to transfer the heat to air used to warm your home. The air is distributed by an air handler or blower, just as in an air-source heat pump system. The system works essentially in reverse when providing cooling, capturing heat from your indoor environment and moving it outside, where the heat is released into the ground or water.

Geothermal Heat Pumps: Efficiency

The operation of geothermal heat pumps means that these system can be incredibly efficient. When providing heating, for example, it's not uncommon for geothermal systems to achieve efficiency levels of 300 or 400 percent. This means that the system produces three or four units of heating for each unit of electricity consumed by the equipment. Geothermal systems reach this exceptional level of efficiency because 1) they do not burn fossil fuels to produce heat; and 2) unlike an air-source heat pump, which is absorbing or releasing heat energy into extremely hot or cold air, a geothermal heat pump has a much less energy-intensive heat-exchange process. it just takes a lot less energy to absorb/release heat from/into moderate temperatures that you find in the ground or underwater.

Geothermal Heat Pumps: Benefits

The tremendous efficiency of geothermal heat pumps translates into their greatest benefit: substantial savings on monthly heating and cooling costs. A geothermal system can slash heating costs by 70 percent or more over the comparable performance of a gas heating system. They can be up to 30 percent more efficient than a standard air-source heat pump. Electricity usage for heating and cooling can be reduced by up to 50 percent.

Some additional benefits of geothermal heat pumps include:

  • Savings on water heating: A geothermal system can be configured to provide hot water for home use. The equipment diverts a small percentage of the heat it captures to heating water. Geothermal water heating can reduce residential hot water costs by up to 30 percent.
  • Quick recovery of initial investment: Since geothermal systems are so efficient and reduce monthly expenses so much, the initial investment in geothermal equipment can be recovered quickly through monthly savings alone. It's not uncommon for geothermal systems to pay for themselves within three to five years.
  • Long functional life: Geothermal heat pump systems are relatively sturdy and reliable, requiring minimal preventive maintenance and infrequent repairs. The heat pump component inside the house can be expected to last for about 20 years or more. Loop pipes are typically guaranteed for up to 50 years. If you install a geothermal system, you can expect a long and reliable functional life from the equipment.
  • Quiet, safe operation: Geothermal systems operate very quietly without the noise associated with furnaces and air conditioners. They have no outside unit cycling on and off throughout the day. They are also much safer than heating systems that burn fossil fuels and combine a volatile fuel source with an open flame. Except for the minimal electricity needed to operate the fans, geothermal equipment does not utilize energy sources that produce greenhouse gases or potentially dangerous substances such as carbon monoxide. Since the loop is mostly inaccessible, there is no chance of accidental burns or injuries associated with hot pipes.
  • Improved and more consistent indoor comfort: The operation of geothermal equipment means that it produces a consistent level of heating and cooling throughout your home. There is always plenty of heat available for home comfort, even during the coldest days of winter. Geothermal systems do not lose efficiency when the outdoor temperature drops below freezing. Geothermal heat pumps are also appropriate for any size home in any climate, making them applicable in just about any region of the country.
  • Tax credits: Geothermal heating and cooling systems can often qualify a homeowner for income tax credits that help offset the cost of purchasing and installing the equipment. Federal tax credits continue to be available for geothermal systems installed on or before Dec. 31, 2016. State and local governments may also offer renewable energy incentives that support the installation and use of geothermal equipment. Utilities and manufacturers may offer discounts and rebates, as well.

Geothermal Heat Pumps: Disadvantages

For all their benefits, there are still two major disadvantages to using geothermal heat pumps.

  1. Larger initial investment: Geothermal heat pump systems will require a larger up-front investment for both equipment and installation. Heat pumps in general are more costly than traditional air conditioners or furnaces. The installation is a more complex process that will require expert preparation, then trenching and digging in your yard, or access to a water source, for putting in the loop pipes.
  2. Disruption of yards and landscaping: Since the ground-loop pipes must be buried underground relatively close to your home, your yard will have to be disrupted to create the trenches that contain the pipes, or the deep drilling needed for a vertical loop system. This could destroy landscaping, require the removal of trees or shrubs, or create a situation in which outbuildings must be moved or eliminated completely. Geothermal installers recognize the potential damage that can occur to lawns and yards, and the better installers will be capable of restoring your outdoor environment to near-new condition.

Geothermal Heat Pumps: Choosing a Contractor

If you decide to proceed with purchasing a geothermal heat pump, make sure the equipment is installed by a licensed contractor with technical knowledge of geothermal equipment. Geothermal installation is a complex process that requires specialized expertise to ensure safe, efficient and correct operation of the system. When selecting a geothermal contractor, you should:

  • Make an effort to learn about geothermal equipment: The more you know about geothermal systems and their operation, the better decision you'll be able to make when it comes to choosing a contractor.
  • Evaluate the contractor: Use a contractor who is properly licensed, insured and bonded. Ask to see licenses and certifications; a legitimate contractor will be happy, even proud to explain his and his company's qualifications to serve you. Ask if the contractor belongs to any industry organizations or trade associations, which tends to indicate a dedication to the HVAC industry and its best practices. Make sure your contractor can handle all aspects of geothermal installation, maintenance, and repair, including excavation for the ground loop (or sinking of the water loop), heat pump installation, and any service that may be needed later.
  • Evaluate all aspects of using and installing a geothermal system, not just price: You can expect to pay a premium price for quality geothermal equipment and installation. However, the benefits of using geothermal systems make the cost easily justifiable. When choosing a contractor, look at more than just the cost estimate. Low-cost installation or equipment may not turn out to be the bargain it looks like at the beginning.
  • Get a signed, itemized contract: Make sure your contractor provides an itemized contract that is signed by you and the contractor's representative. The contract should specify what you're buying, what services are being performed, and what you can expect from the transaction.

With more than 100 years of experience in the HVAC industry, Griffith Energy Services, Inc. serves the Mid-Atlantic communities of Baltimore, Hagerstown, Edgewater and Frederick, Maryland; Manassas and Berryville, Virginia; and Martinsburg and Charles Town, West Virginia, with high-quality, professional installation, maintenance and repair. Contact us today for more information on geothermal heat pumps and for expert assistance with deciding if a geothermal system is right for your residential needs.

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