Heat pumps and geothermal systems are not the same thing, though geothermal is one type of heat pump

A heat pump is a broad category of equipment that moves heat from one place to another using electricity and refrigerant. A geothermal heat pump is a specific kind of heat pump that pulls heat from the ground or groundwater instead of from the air. Most residential heat pumps you see installed are air-source models, which pull heat from outdoor air. Geothermal systems are less common, more expensive to install, but often more efficient over their lifetime.

The confusion happens because the terms get used interchangeably in casual conversation, but they describe different things. When a contractor says "heat pump," they usually mean an air-source model unless they specifically say "geothermal." Understanding the difference matters because the two systems have different installation costs, space requirements, and long-term operating costs.

Key Takeaways

  • Heat pumps are a category of systems that move heat; geothermal heat pumps are one type within that category.
  • Air-source heat pumps pull heat from outdoor air and are the most common residential model; geothermal systems pull heat from underground.
  • Geothermal systems cost significantly more to install because they require digging or drilling, but they often run more efficiently in cold climates.
  • Both types heat in winter and cool in summer by moving heat rather than generating it, so both are more efficient than furnaces or air conditioners.
  • Geothermal systems work in any climate, but air-source models lose efficiency in very cold weather without a backup heating source.

How air-source and geothermal heat pumps differ

An air-source heat pump exchanges heat with the outdoor air through a condenser unit sitting outside your house. In winter, it pulls heat from the cold air and moves it indoors; in summer, it reverses and pulls heat from inside and releases it outdoors. The system works as long as outdoor air exists, but the colder the air gets, the harder the compressor has to work, and efficiency drops.

A geothermal heat pump exchanges heat with the ground or groundwater through a loop of pipe buried underground or drilled into a well. Ground temperature stays relatively stable year-round—usually between 45 and 75 degrees depending on your location and depth. Because the system always has a warmer or cooler source to exchange with, it does not have to work as hard, especially in very cold climates. The tradeoff is that installation requires excavation or drilling, which costs thousands of dollars more upfront.

Both systems use the same basic refrigeration cycle and both can heat and cool. The difference is what they exchange heat with: air versus ground.

Installation costs and space requirements

An air-source heat pump typically costs between $4,000 and $8,000 installed, depending on your region and the size of your home. Installation is relatively straightforward: the outdoor unit sits on a pad or mounts on a wall, and refrigerant lines run to an indoor unit or to your existing ductwork. You need outdoor space for the condenser, but not much—usually a few feet of clearance on one side of your house.

A geothermal system costs between $15,000 and $30,000 installed, sometimes more. The bulk of that cost is the ground loop. A horizontal loop requires excavating trenches across your yard—typically 4 to 6 feet deep and 100 to 300 feet long depending on your heating and cooling load. A vertical loop requires drilling one or more boreholes 150 to 300 feet deep. Both methods need space and can disrupt landscaping. If your lot is small or you have bedrock close to the surface, installation becomes difficult or impossible.

Some areas offer rebates or tax credits for geothermal systems because they are more efficient. Check with your local utility and the federal tax credit programs to see what is available in your region—these can offset some of the upfront cost.

Efficiency in different climates

Air-source heat pumps work in most climates, but their efficiency drops as outdoor temperature falls. In mild climates—roughly zones 8 and warmer—an air-source system can heat your entire home without backup. In colder climates, most air-source systems include a backup electric heating element that kicks in when outdoor temperature drops below about 35 degrees. That backup heating is less efficient than the heat pump itself, so your operating costs rise during the coldest months.

Geothermal systems maintain high efficiency across all climates because ground temperature does not fluctuate the way air temperature does. In very cold regions, a geothermal system will heat your home more efficiently than an air-source system, which means lower monthly heating bills. Over 15 to 20 years, that efficiency gain can offset the higher installation cost, especially if you stay in the home long enough to recoup the investment.

If you live in a climate where winter temperatures regularly drop below zero, geothermal makes more financial sense. If you live somewhere mild or moderate, an air-source system usually pays for itself faster because the installation cost is so much lower.

When geothermal makes sense

Geothermal is worth considering if you have adequate land, plan to stay in your home for at least 10 to 15 years, live in a cold climate, and have the upfront capital or can finance the system. It is also a good choice if you are replacing an old heating system and want to eliminate fossil fuels entirely—geothermal can be your sole heat source without a backup furnace.

Geothermal does not make sense if your lot is small, you have shallow bedrock, you plan to move within a few years, or you cannot afford the installation cost. In those cases, an air-source heat pump is a practical alternative that still saves energy compared to a traditional furnace and air conditioner.

Maintenance and lifespan

Both air-source and geothermal heat pumps need annual maintenance: a technician should inspect the refrigerant charge, clean or replace filters, and check electrical connections. Air-source units also need the outdoor condenser coil cleaned periodically to remove dust and debris. Geothermal systems have fewer outdoor components exposed to weather, so they often require less maintenance overall.

A well-maintained air-source heat pump lasts 15 to 20 years. A geothermal system typically lasts 20 to 25 years for the heat pump itself, and the ground loop can last 50 years or longer if installed correctly. That longer lifespan is another reason geothermal can make financial sense over decades, even though the upfront cost is higher.

Frequently Asked Questions

Can I convert an air-source heat pump to geothermal later?

Not easily. The systems use different heat exchangers and controls. If you want to switch, you would typically replace the entire system. Plan ahead: if you think geothermal might make sense for your home, have a geothermal contractor evaluate your property before you install air-source equipment.

Do geothermal systems work in areas with clay soil?

Yes. Clay actually conducts heat well, which is why geothermal works in many regions. The real limiting factors are lot size, bedrock depth, and local groundwater. A geothermal contractor can do a site assessment to tell you whether your property is suitable.

What happens to a heat pump in a power outage?

Both air-source and geothermal heat pumps stop working without electricity. If you want heating during an outage, you need a backup generator or a backup heating source like a wood stove or propane heater. Some people install a small generator specifically to run their heat pump during emergencies.

Is geothermal worth it if I only need cooling?

Geothermal is less cost-effective for cooling-only applications because the upfront expense is high and you do not get the winter heating benefit. An air-source heat pump that cools and heats is usually the better choice if cooling is your main need.