What is a Geothermal Heat Pump?

Geothermal heat pumps continue to make a name for themselves as an energy efficient and environmentally friendly heat source. They don’t rely on electricity to generate heat, which leads to less greenhouse gas emissions as well as energy savings for you!

But how do geothermal heat pumps warm a home? A few feet below the surface, the ground remains a constant temperature of around 45-70 degrees Fahrenheit. Depending on the location, that temperature remains the same all year long.

These systems utilize underground heat, exchanging heat energy with the ground to warm or cool a home.

How do they work?

Geothermal, or ground-source, heat pumps attach to ground loops. These ground loops install underground, in trenches, or underwater. A liquid refrigerant circulates within the ground loops, absorbing geothermal energy as it passes through. The refrigerant collects the heat, evaporates into a gas, and carries the heat inside the heat pump system. The gas condenses back into a liquid, which releases that energy. This allows the indoor unit to then distribute that warmth to your home.

The same process works in reverse to cool your home, pulling warmth from the room and depositing it into the ground.

These systems can function in warm and cool climates. However, if you live in a colder climate, we recommend using supplemental heating as well.

How efficient are they?

While many heating systems require electricity to create or generate heat, geothermal heat pumps transfer heat instead. They only require electricity to power them, which reduces the amount of energy you use, as well as your energy bill.

You can check the efficiency of the heat pump with the Energy Efficiency Rating (EER) and Coefficient of Performance (COP) rating. The EER rating will tell you how efficiently the heat pump cools. The COP rating will tell you how efficiently it heats. The higher the rating, the more efficiently the heat pump performs.

Types of Geothermal Heat Pumps:

You have options when it comes to the type of heat pump you choose. New geothermal technologies continue to get developed, including enhanced geothermal systems which could allow for more people to use high efficiency geothermal heat pumps and geothermal resources. You can also find options that utilize a desuperheater for domestic hot water.

When deciding which option to choose, consider ground loop orientation, installation costs, operational costs, and heat exchange method. Below we list some of the more common types of geothermal heat pumps:

Closed vs. Open Loop Systems:

Closed loop systems continuously circulate the same refrigerant within ground loops. As a closed system, nothing goes in or out except for heat energy.

Open loop systems use water from a nearby clean water source as a refrigerant. Unlike closed loop systems, they only use this water once. Open loop systems may return the water through a discharge well or drainage ditch. They may also direct it back to a pond or lake.

Not all municipalities allow open-loop systems as they can disturb or contaminate the water source.

Closed Ground Loop Orientations:

Horizontal closed loop systems require deep trenches to install the loops into. According to the U.S. Department of Energy, they serve as cost-effective options for residential installations.

Closed loop vertical systems work best in areas with shallow soil or areas with strict landscape requirements. Instead of trenching, the ground loops install vertically in holes, using a U-Bend to form a loop.

Pond/Lake closed loop systems exchange heat energy with a body of water instead of the ground. As a closed loop system, water from the pond or lake does not enter the system, only heat energy.

Though they function as a lower cost alternative, pond/lake systems must meet strict volume, depth, and quality requirements to install.

Dual-Source Heat Pumps:

You can find dual-source heat pumps that combine geothermal and air-source heat pump technology. They function as a more affordable alternative to only geothermal units. While not quite as energy efficient as geothermal, dual-source provide more energy efficiency than air-source units.


Heat and cool your home in an energy efficient and eco-friendly way with a geothermal heat pump system. Find geothermal heat pumps at HomElectrical!

Recommended Reading

Electricity is produced using fossil fuels, which release greenhouse gases. Discover which heating and cooling system works best for your home or business.

If you need to replace your old HVAC unit, consider the pros and cons of a ductless mini split system. A mini split system can reduce your heating cost by 25-50%, has improved safety over baseboard heaters, only requires you to make 3 small holes, has optimized airflow, and can climate control individual rooms.

Avery Dietzen
Avery Dietzen

Originally from Wisconsin, Avery earned her degree in English before making the trip down to the Atlanta, GA area. Writer by day, reader by night, she prides herself on having a creative outlook and tries to instill that in everything she writes. As a content writer for HomElectrical, she uses her skills to share tips and tricks about lighting, HVAC, and going green. If she’s not writing, she’s reading, painting, hanging out with her dog, or spending time with family and friends.

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