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Ground-source Models
Ground-source Heat Pumps
Ground-source models are very efficient, taking advantage of the earth’s constant temperature.
Ground-source Models
Why install a ground-source heat pump?
A ground-source heat pump takes advantage of a renewable resource: the heat underground. Unlike outside air, the temperature of the earth, beginning just 5 to 10 feet below the surface, stays at about 50 to 60 degrees F year round. The same is true of ground water from subsurface aquifers, as well as water below the surface of lakes, ponds and rivers. You do not need a geothermal resource (hot water or steam) to take advantage of this technology. Ground-source heat pumps work well throughout PGE’s service area. They are a premium heating and cooling source that can cost considerably more than other options. Good applications can include:
  • Homes needing energy-efficient heating and cooling
  • Homes with access to ground water or surface water
  • Homes with sufficient outside space for a buried ground loop
  • Homes using forced-air or radiant hydronic wall registers
  • New homes where radiant hydronic piping can be located in the floor or ceiling

How a ground-source heat pump helps you
Ground-source heat pumps are among the most energy efficient of all heating and cooling systems. The advantages of ground-source heat pumps include:
  • Use up to 72 percent less energy per year, compared to electric resistance heating with standard air conditioning*
  • Efficiencies of 300 to 600 percent on the coldest winter nights, compared to 175 to 250 percent efficiency for a standard air-source heat pump*
  • Zero emissions
  • Embraced by LEED™ (Leadership in Energy and Environmental Design) and other green building organizations

How a ground-source heat pump works
A geothermal heat pump uses the constant, below-ground temperature of soil or water to heat and cool your home. In winter, it pulls heat from the earth or water (1) and brings it inside, using a heat exchanger (2). In summer, the process reverses to cool your home. The system usually includes a ground loop of piping, a heat exchanger and a distribution loop inside your home. You also can install a traditional, ducted air supply instead of the inside distribution loop. Some systems also supply hot water, further increasing energy efficiency.

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Closed loop system illustration

Hire an experienced contractor
These installations can be complex, so it’s critical to use a qualified licensed contractor with experience in ground-source heat pump installations. The Oregon Department of Energy maintains a statewide listing of tax-credit certified technicians (PDF).

Purchasing advice
The U.S. Department of Energy website has extensive information on how to buy an energy-efficient, ground-source heat pump (PDF).

*Source: U.S. Department of Energy

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