The Basics of Geothermal Heating Systems

By: Beth Krietsch Environmental responsibility, Featured

Geothermal heating is growing in popularity as individuals are increasingly seeking clean, efficient, and renewable energy options. The process heats your home through transferring energy that’s been extracted from the earth. Geothermal heating systems are expensive to install, but the payoff in reduced utility bills over time is large.

The basics of geothermal heating systems

Geothermal heating systems, transfer heat through an underground system of water-filled pipes that run between the house and the ground. Just a few feet under the earth’s surface, the ground maintains a stable temperature between 45°F and 75°F year round. In cool winter months, the piping system brings heat into your home by using this temperature-stable underground as a means for energy exchange. In the summer, the piping system extracts warm air from your home and bring it back to the earth. Rather than creating warmth by burning fuel, a geothermal heating system creates warmth by moving heat from the earth to your house. In addition to heat, some geothermal heat pumps are even capable of supplying your home with hot water.

A significant benefit of using geothermal heat pumps is that the energy source is reliable, consistent, and stable, so you won’t need to rely on the strength of the sun, wind, or outdoor air temperatures like with some other types of environmentally friendly heating. Indoor components of geothermal heating systems last about 25 years, and the underground piping system can last 50 years or more. This type of heating system is also known to be extremely quiet—you won’t even notice the heat pump is running.

Geothermal coils eight feet underground. This is the end of system used to heat and cool a large residential home.

Types of geothermal heating systems

Most geothermal heat pumps fall under four different categories. The first three are considered closed-loop systems.  

  • Horizontal—In a horizontal system, pipes are installed at least six feet below ground. This variety of installation requires a large plot of land, but is less expensive than a vertical system. This is a very common installation type for residential homes.
  • Vertical—A vertical system is useful when you do not have a huge expanse of terrain to work with. To deploy this system, pipes are installed into holes with a four-inch diameter that are approximately 15 feet apart from one another. The holes extend to a depth of 100–400 feet.
  • Pond/lake—This type of system uses heat from water rather than the ground. Coiled pipe is installed at least eight feet deep and water sits atop the piping. When there is a body of water nearby, this is often the most affordable option.
  • Open loop—Open loop systems are less common. To work, water from a well or body of water is used to transfer heat and the water circulates through the system.

Cost of geothermal heating systems

Geothermal heat pumps are expensive. Many cost $20,000 or more to install, and pricing depends on location, lot size, soil type, and landscape.

But there is an upside—the payback on energy savings is huge, especially if you plan on staying in your home for many years, and federal, state, and local tax credits are available to help reduce costs as long as the system meets ENERGY STAR requirements. According to the US Department of Energy, most will be able to recoup their initial investment within 2–10 years of having the system installed.

A trench filled with plastic tubing used for the installation of a geothermal residential heating and cooling system.

Efficiency of geothermal heating systems

ENERGY STAR ranks geothermal as one of the most efficient heating technologies available, and the US Department of Energy says that heat pumps can lower heat-related home energy use by nearly 50% compared to electric systems.

Maintenance requirements

Maintenance for geothermal heat pumps is minimal. Expect to do a semi-annual filter change and annual coil cleaning, but beyond these basic maintenance steps, you won’t be burdened with expensive or time-consuming upkeep if the system has been properly installed.

Installation of geothermal systems

Geothermal heating pumps must be installed by a professional. You can find a qualified individual to install your geothermal heating system by searching listings of qualified installers through the Ground Source Heat Pump Association, Geothermal Heat Pump Consortium, or by calling your local utility company. The US Department of Energy recommends asking potential installers for references regarding geothermal heat pump installations completed at least a few years ago and checking these references before making a hire.

Note that heat pump installation can be highly disruptive to your property. Hold off on planting gardens or putting money into your landscaping until installation is complete.

 

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