Radon & Your HVAC — Homeowner Guide

What is radon and how does it enter a house?

Radon is a naturally occurring, invisible gas that can seep into a house through the foundation. It moves from the ground into living spaces when the air pressure inside the building is lower than the pressure outside.

Radon originates naturally and travels upward from the ground. When a house sits on a foundation, porous materials provide a pathway for this gas to enter the living space. The movement of this gas is largely driven by pressure differences between the interior and exterior environments. If the interior of a house operates under negative pressure, the building acts like a vacuum, pulling outside air and ground gases inward. While radon testing and mitigation are specialist work, it helps to understand how the air inside your house behaves. The way air moves through a building dictates how various gases travel from room to room.

Why does indoor air pressure matter for radon?

Indoor air pressure determines whether a house pushes air out or pulls air in. When a house experiences negative pressure, it draws in outside air and ground gases, which can increase the concentration of radon indoors.

Air pressure is a fundamental concept in building science. When the air pressure inside is higher than outside, the house pushes air outward through gaps. Conversely, negative pressure occurs when the indoor pressure drops below the outdoor pressure. Under negative pressure, the house attempts to equalize by pulling air in from any available opening. Because the foundation is in direct contact with the ground, negative pressure can draw naturally occurring gases upward into the living space. Exhaust fans remove air from the house, and if replacement air does not enter easily, the indoor pressure drops. Your heating and cooling equipment also moves a considerable volume of air, making it a factor in the pressure balance.

Can an air conditioning or heating system cause a radon problem?

Heating and cooling equipment does not create radon, but it can alter indoor air pressure. If ductwork is unbalanced or leaking, the system might inadvertently depressurize the house, encouraging more ground gases to enter.

A central heating and cooling system uses a network of ducts to circulate air. The equipment pulls air from the house through return ducts, conditions it, and pushes it back through supply ducts. However, ductwork is rarely airtight. If the return ducts have leaks, the system might pull in air from unconditioned spaces, changing the pressure dynamics of the entire house. If the supply ducts leak, the system pushes conditioned air into spaces where it is not needed, which can depressurize the main living areas. You can learn more about how equipment manages air in our guide to how a heat pump works.

How does ventilation affect indoor air quality?

Ventilation introduces fresh outdoor air into the house, which helps dilute indoor pollutants. Proper ventilation strategies balance the air coming in with the air going out, which helps maintain neutral indoor pressure.

Without adequate ventilation, the air inside a house becomes stale. Odors, dust, and naturally occurring gases can accumulate. Introducing fresh air is necessary to dilute these pollutants and improve overall indoor air quality. Simply running exhaust fans removes stale air but creates negative pressure if fresh air is not actively brought in to replace it. Exchanging indoor and outdoor air helps maintain neutral pressure within the house. By controlling the introduction of fresh air, you can dilute indoor contaminants without inadvertently turning the house into a vacuum.

Should you use your heating and cooling equipment to mitigate radon?

No, heating and cooling equipment is not designed for radon mitigation. Radon mitigation is specialist work that requires dedicated systems to vent gases from below the foundation directly to the outdoors.

It is a misconception that running an air conditioner or furnace fan will solve a radon issue. While circulating indoor air might mix the air, it does not remove the source of the gas or address the underlying pressure dynamics pulling it in. Dedicated radon mitigation systems operate independently of your heating and cooling equipment. These systems use a specialized fan and piping to draw air from beneath the foundation and exhaust it above the roofline. You might find our article on indoor air quality solutions and your heating system helpful.

What steps should you take if you are concerned about radon?

Testing is the standard method to determine if a house has elevated radon. If levels are high, you should contact a specialized mitigation contractor to install a dedicated venting system.

Testing determines the concentration of the gas in a living space. If a test indicates elevated levels, the next step is to consult a mitigation specialist. Mitigation contractors design systems tailored to the specific foundation of the house. When a mitigation system is in place, it works to divert the gas away from the living areas. While mitigation is handled by specialists, you can still take steps to improve your overall indoor air quality. Keeping your heating and cooling equipment operating with balanced airflow helps maintain neutral indoor pressure. You can also monitor your thermostat settings, check for visible obstructions around outdoor units, and keep a clean air filter in place.

When should you contact a professional?

If you notice uneven temperatures or excessive dust, a professional can help you weigh the options for your home.

Managing the air inside your house involves understanding how the different systems interact. Talk with Airflow Systems about your options for your heating and cooling system.

If you have questions about your ductwork, airflow, or general indoor air quality, contact Airflow Systems through our contact page or call (434) 979-4328.