Should You Keep Your HVAC Fan Running?

by | Oct 27, 2022

Heating, ventilation, and air conditioning systems provide easy access to fresh air with a fan control right on your thermostat. Fans help circulate the air around a room, working to remove hot air until the desired temperature is reached. HVAC fans are equipped with two working modes, Auto and On. But which one is best? 


Both modes have benefits and disadvantages, so much will depend on the preferences of those living in the home. If you experience cold or hot spots in your home, running your HVAC fan can help regulate a comfortable temperature. But some argue the Auto setting is more cost and energy efficient. Now, the integration of smart thermostats offers the capability for custom fan settings. Do you know which HVAC fan setting is right for you?

HVAC Fan Settings

Fans circulate air throughout the home, providing ventilation and maintaining a comfortable thermal consistency. HVAC fans can help remove pollutants and contaminants from the air and are integral to maintaining indoor air quality


The ON Setting

Setting the fan to ON tells your HVAC fan to run continuously, blowing air even when the system is not heating or cooling. 


The AUTO Setting

Setting the fan to Auto tells your HVAC fan to run only when the system is heating or cooling. Once the temperature inside reaches the temperature setting on your thermostat, the system turns off automatically– including the fan. 


Benefits of Keeping Your HVAC Fan Running

  • Increase air circulation in your home. Setting your fan to ON creates an even distribution of heating and cooling. This eliminates cold and hot spots in less-ventilated areas. 
  • Extend the life of your HVAC system. It may sound counterintuitive, but keeping your fan running can be easier on your system in the long run. With fewer starts and stops, your HVAC fan may last much longer. 
  • Eliminate unwanted odors. When the fan is running continuously, you don’t have to worry about the room getting too stuffy. Keeping your fan running keeps the air clean and eliminates odors. 
  • Improve indoor air quality. Keeping the HVAC fan on ensures that your air is being filtered. Filters remove tiny particles like mold, dust, pollen, allergens, bacteria, and even harmful contaminants like lead. The Environmental Protection Agency (EPA) suggests keeping the fan on to guarantee that the air is safe from contaminants. 


Disadvantages of Keeping Your HVAC Fan Running

  • Increased energy bills. Keeping your fan running could result in higher energy bills. 
  • More maintenance is required. More use requires more maintenance! If the air is being circulated constantly, the air filters will become clogged more quickly. Change them frequently, as often as every 3 to 4 weeks.
  • Introduce hot air in the hotter months. Ducts in attics and walls can fill with hot air in the hotter months, and keeping your HVAC fan running can result in circulating this hot air throughout the house. 
  • Potential humidity issues. Running the fan continuously can make it difficult to maintain safe humidity levels. When the HVAC system turns off, the condensation from the evaporator coils collects at the bottom and is removed from the home. If the system is kept running, this condensation evaporates back into the air and can contribute to high humidity levels and the potential for mold. 


Benefits of Switching Fan to Auto Setting

  • Save on energy bills. Choosing Auto as your HVAC fan setting means it will only run to achieve the desired temperature. Since the fan is only running when the system is heating or cooling, the Auto setting is more energy efficient and could help reduce your energy bill
  • Maintain preferred humidity levels in your home. The Auto feature is created for optimal humidity control within the home. As soon as the desired temperature is reached, the fan stops along with the heating or cooling system, allowing the condensation to be collected and discarded. 


Disadvantages of Switching Fan to Auto Setting

  • Temperature inconsistencies. When the system shuts off automatically, the air will stop circulating. The hot air in the home will continue to rise and contribute to uneven temperature.
  • Wear and tear on your HVAC system. The Auto setting can result in more stress for the fan motor as it turns on and off more frequently. More wear and tear on your HVAC fan will result in more maintenance and a shorter lifespan.


Which HVAC Fan Setting is Right for You?

Should you keep your HVAC fan running? When it comes to maintaining the comfort of your home, it comes down to managing your own personal preferences and priorities. Whether you decide to set your AC fan to ON or Auto will depend on you, as both have their pros and cons.


HVAC fans are essential to indoor air quality. HVAC fans don’t bring in outside air. Rather, they circulate the air inside the home to regulate the temperature and eliminate hot and cold spots. Keeping the fan running is a great way to remove stale air and improve ventilation and is perfectly safe for extended periods of time. Choosing Auto mode can result in a reduced energy bill and more humidity control. 


Note: If you live where humidity levels are particularly high, you may want to consider using the Auto feature. If it’s already humid, keeping your fan running can lead to excess moisture and contribute to mold growth. 


To make the most of your HVAC system and fan settings, remember to maintain and service your system regularly. Contact us today to extend the life of your heating and cooling systems with preventative HVAC maintenance. 

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