Should You Leave Your HVAC Fan On?

The fan that moves air through your home is a crucial component of running your HVAC system. Your thermostat has two options: fan on or auto. But which setting should you use?

The answer depends on your home’s needs, energy goals, and personal comfort preferences. Understanding the pros and cons of keeping your HVAC fan on all the time is important. This knowledge will help you choose what is best for your home’s comfort and efficiency.

HVAC Fan Settings: On vs Auto

Your HVAC fan circulates cooled or heated air from your HVAC unit through your ductwork and back into your living spaces.

When the fan is set to “on,” it runs all the time, even when your AC or furnace isn’t heating or cooling your home. It just provides continuous airflow. When the fan is set to “auto,” it only runs during the heating or cooling cycle.

Benefits of Leaving Your HVAC Fan On

There are some advantages to running your HVAC fan continuously.

Improved Air Circulation

Leaving your HVAC fan always on promotes even air distribution. This can help eliminate hot or cold spots and improve comfort, especially in larger homes or multi-story properties.

Better Indoor Air Quality

When your fan is always on, it continuously pulls air through your HVAC system’s filter. This means more frequent filtration of dust, allergens, and other airborne particles.

Enhanced Humidity Control

Consistent air flow helps regulate moisture levels throughout your home, reducing the risk of mold and mildew in bathrooms, basements, or other damp areas.

Drawbacks to Having Your HVAC Fan Always On

While there are benefits, there are also a few things to consider before deciding to have your fan always on.

Higher Energy Bills

The fan motor uses electricity. If you always leave the HVAC fan on, it will use more energy. The “auto” setting only runs when needed, saving energy.

Increased Wear and Tear

Running the fan motor constantly can put added stress on it. This may shorten its lifespan and lead to more HVAC system repairs.

More Noise

HVAC fans are usually quiet, but their hum can be noticeable. This can be distracting, especially at night or in quiet places like bedrooms or home offices.

When to Use “On” or “Auto” for Your HVAC Fan

Choosing between the HVAC fan settings depends on what you value most, whether it’s comfort, air quality, energy savings, or quietness.

You might consider running your HVAC fan continuously if:

• You want better air circulation, especially in homes with uneven temperatures, multiple floors, or stuffy rooms.
• You or your family have allergies or asthma and you want to filter out dust and allergens regularly.
• You live in a humid area, have moisture-prone spaces like basements or bathrooms, and want to prevent mold or mildew buildup.

On the other hand, keeping the HVAC fan on auto may be the better option if:

• You’re aiming to reduce your energy bills, since the fan will only run when your system is in a heating or cooling cycle.
• You have a newer or more energy-efficient HVAC system that balances comfort and performance well.
• You’re sensitive to background noise and want a quieter environment, especially at night.

Ultimately, the best setting depends on your home’s layout, comfort needs, and energy goals.

Get Personalized HVAC Guidance from Thornton Heating

At Thornton Heating Service, we specialize in helping Chicagoland homeowners make informed decisions about their HVAC systems.

Our skilled technicians can check how well your system works, find airflow problems, and suggest the best fan setting. This will help improve comfort and save energy.

We can help with uneven temperatures, indoor air quality concerns, and utility bill reductions. We offer a complete range of cooling, heating, and indoor air quality services. Our goal is to give you the best home comfort possible.