How Geothermal Works in Central Virginia

What is a geothermal heat pump?

A geothermal heat pump is a heating and cooling system that transfers heat between your house and the earth. It uses the temperature of the ground to provide conditioned air during hot weather and cold weather.

Traditional heating and cooling systems exchange heat with the outside air. A geothermal system exchanges heat with the earth. The ground stays steadier than outdoor air. By tapping into this environment, the system can move heat rather than generating it from combustible fuels. You can read more about geothermal installation and replacement to understand the equipment involved.

A heat pump operates by moving thermal energy from a source to a destination. When you want to warm your living space, the system gathers thermal energy from the outdoor environment and moves it indoors. When you want to cool your living space, the process reverses.

How does the ground loop function?

The ground loop is a network of underground pipes that circulates a water-based fluid. This fluid absorbs heat from the ground or releases heat into the ground, depending on whether the system is heating or cooling.

The ground loop acts as the bridge between your indoor equipment and the earth. The fluid inside the pipes absorbs thermal energy from the ground during cold weather. During hot weather, the fluid carries thermal energy from your house and releases it into the ground. The fluid travels in a cycle, moving from the underground pipes to the indoor unit and back again.

The fluid inside the pipes is a mixture of water and a standard antifreeze solution. This mixture prevents the fluid from freezing when the ground temperature drops. For more details on loop configurations, see our guide on whether geothermal is right for your property.

How does the system cool your home?

During hot weather, the geothermal system removes heat from your indoor air and transfers it to the ground loop. The fluid carries this heat underground, where it is absorbed by the cooler earth.

The cooling cycle relies on the phase changes of the refrigerant. When the warm indoor air blows across the evaporator coil, the liquid refrigerant absorbs the thermal energy and turns into a gas. This gas travels to the compressor, which increases its pressure and temperature. The hot refrigerant gas then moves to the heat exchanger. At the heat exchanger, the thermal energy moves from the hot refrigerant to the cooler fluid circulating from the ground loop.

As the refrigerant loses thermal energy, it condenses back into a liquid state. This liquid refrigerant then flows through an expansion valve. Meanwhile, the ground loop fluid travels back underground. For related cooling topics, you might review our post on how your air conditioner works.

How does the system heat your home?

In cold weather, the process reverses. The ground loop extracts heat from the earth and carries it to the indoor unit, where the heat pump moves the heat and distributes it throughout your house.

The reversing valve is a component that allows the heat pump to provide both heating and cooling. By changing the direction of the refrigerant flow, the reversing valve switches the roles of the indoor coil and the heat exchanger. During cold weather, the heat exchanger acts as the evaporator, absorbing thermal energy from the ground loop fluid.

The compressor plays a vital role in this process by pressurizing the refrigerant gas. This pressurization raises the temperature of the refrigerant, allowing it to provide warmth to the indoor air. If you are curious about how other heat pumps operate, read our guide on how a heat pump works in cold weather.

What components make up the indoor unit?

The indoor portion of a geothermal system contains the compressor, heat exchanger, blower motor, and air filter. These components work together to transfer thermal energy and circulate conditioned air through your ductwork.

Inside the cabinet, the blower motor is responsible for moving air through the ductwork. The blower motor pulls unconditioned air from the return ducts, pushes it over the indoor coil, and forces the conditioned air into the supply ducts. The heat exchanger facilitates the transfer of thermal energy.

The compressor is the engine of the refrigeration cycle, responsible for pumping the refrigerant through the lines and altering its pressure. The indoor unit also houses the control board, which communicates with your thermostat. You can learn more about the importance of airflow and filtration in our post on understanding static pressure and air filters.

How does geothermal differ from air-source heat pumps?

While air-source and geothermal systems use refrigerant to move heat, air-source heat pumps exchange heat with the outside air, whereas geothermal systems exchange heat with the ground.

Air-source heat pumps feature an outdoor cabinet that contains the compressor and the outdoor coil. This outdoor unit is exposed to the elements and uses a large fan to pull outdoor air across the coil. Typical closed-loop geothermal systems do not have an outdoor cabinet with a fan. Instead, the outdoor portion consists entirely of the underground pipe loop. This means the main mechanical components, including the compressor, are typically located inside the house.

Both types of systems rely on a blower motor to circulate conditioned air through the ductwork. The primary distinction lies in the medium used for heat exchange. Homeowners considering different options should note that the federal 25C and 25D tax credits for heat pumps and geothermal ended December 31, 2025. Ask about current utility rebates.

When should you call a professional?

If your geothermal system fails to turn on, produces unusual odors, or struggles to maintain the temperature set on your thermostat, a professional can help you weigh the options for your home.

Homeowners should avoid attempting to service the mechanical parts of the system. The compressor, the heat exchanger, and the reversing valve involve complex refrigeration principles. The control board and the blower motor involve electrical connections. The ground loop involves pressurized fluid circulation. A professional can help you weigh the options for your home if any of these components malfunction. If you notice a sudden change in the operation of your equipment, it is time to seek assistance.

You can schedule the Annual Tune-Up & System Evaluation. If you have questions about your system's performance, talk with Airflow Systems about your options. You can reach out to us by visiting our contact page or calling (434) 979-4328.