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Is It OK To Run an HVAC Fan All Day?

Is it really necessary to have the HVAC fan running all day long? Many people think that it is a waste of energy and money to have the fan running when no one is home. There are also a lot of people who feel that it is OK to have the fan running all day. 

It’s perfectly fine to run your HVAC fan all day. In fact, there are several benefits to doing so. However, there are also some drawbacks to running your HVAC fan all day. One is that it can increase your energy bill. Additionally, it can also add wear and tear to your HVAC system.

The answer to this question may vary depending on who you ask. In this blog, we will look at both sides of the argument and try to come to a conclusion.

Is It Safe To Leave My HVAC Fan Running All Day?

Your home’s HVAC fan is designed to circulate air and keep your home comfortable. But if you’re like many people, you may wonder if running your HVAC fan all day is OK.

Actually, it’s perfectly fine to leave your fan running all day, and there are some benefits to doing so. For one, it can help circulate the air in your home and evenly distribute the temperature. Contrary to popular belief, this can actually help save costs on your energy bill since your HVAC system won’t have to work as hard to maintain a comfortable temperature.

Leaving your fan running also helps to filter the air in your home and can even reduce the risk of mold and mildew growth. Additionally, it can help remove airborne pollutants and improve indoor air quality. So if you’ve been wondering whether it’s safe to leave your HVAC fan running all day, the answer is yes!

Read: Why HVAC Damper Keeps Getting Stuck Closed?

Pros and Cons of Continuous HVAC Fan Usage

There are a few key benefits and disadvantages to running your HVAC fan continuously, even when your system isn’t heating or cooling your home. 


  • Indoor air quality: Continuous fan operation circulates fresh air throughout your home, which can help to improve indoor air quality. 
  • Temperature/humidity balance: Running your fan continuously can help to evenly distribute temperature throughout your home, which can help to avoid hot and cold spots
  • Reduce energy costs: It helps reduce overall energy costs by keeping your home at a more consistent temperature.
  • Prevent mold growth: It helps to lower the humidity in your home, making it less hospitable for mold and mildew to grow. 
  • Remove odors: Running the fan can help remove odors from your home and airborne allergens like dust and pollen. 
  • Reduce stress: When you start your fan, it adds extra stress to your HVAC system. Keeping your fan “on” all the time reduces unnecessary stress from startup and helps prolong lifespan.

So, if you’re looking for ways to improve indoor air quality, reduce hot and cold spots, or save on energy costs, consider running your HVAC fan continuously.


While there are some benefits to running your HVAC fan continuously, there are also some drawbacks to consider. 

  • Expensive: It can significantly increase your energy bills. If you live in an area with high summer temperatures, running your fan continuously can add up quickly. 
  • Decreases lifespan: Continuous fan usage can also shorten the lifespan of your HVAC unit due to wear and tear on the fan. 
  • Shorter motor life: If you run your fan continuously, it will shorten the life of your motor.
  • Filter changes: You’ll need to change your filters more often if you run your fan continuously. This is because the filters will get clogged faster with dust and grime.
  • Seasonal discrepancies: Your home will be less comfortable in the winter and summer if you run your fan continuously.
  • Less humidity control: Continuous fan operation can also lead to less humidity control in your home.

Read: How To Tell If HVAC Zone Damper Is Normally Closed Or Normally Open? 

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Alternative Option: HVAC Fan Auto Mode

HVAC fan auto mode is a setting that allows your system to automatically regulate the speed of the fan based on conditions within your home. This can help to improve indoor air quality and save you money on your energy bill.

If you’re looking for an alternative to continuously running your HVAC fan, you may consider using the fan’s auto mode. Auto mode will only turn the fan on when the system is actively heating or cooling your home. This can save you money on your energy bill and prolong your HVAC system’s life.

There are a few things to keep in mind when using the auto mode. You’ll need to ensure that your HVAC system is appropriately sized for your home. If it’s too small, the fan may run continuously in an effort to keep up with your heating or cooling needs. You’ll also need to adjust the settings on your thermostat to accommodate the fan’s auto mode. 


  • Energy-efficient: Auto mode can help save energy. The fan will only run when needed, so it won’t waste energy when it’s not in use. Additionally, the fan will only run at the necessary speed, which also helps to save energy.
  • Reduces wear and tear: By only running the fan when needed, you’ll be putting less wear and tear on it. This can help the fan last longer.


  • Poor heating/cooling: If your home has poor insulation, the fan may not be able to keep up with the demand, which can be frustrating. 
  • Ineffective ventilation: If the fan is set to a lower speed, it may not be able to effectively circulate the air in your home.
  • Low fan speed: The fan will only run at its lowest setting when in auto mode. So if you have a large home or a home with high ceilings, the fan may not move enough air to make a difference.

Read: Why HVAC Zone Damper Actuator Making A Clicking Noise? How To Troubleshoot?

HVAC Auto or Continuous: Which Is Better?

The answer to this question depends on the climate you live in and the efficiency of your HVAC system. In general, it’s best to let your fan run all the time in hot climates, as this will help keep your home cooler. In cooler climates, you can set your fan to Auto mode, as this will save energy.

The budget option would be to choose Auto mode, which will massively reduce operational and maintenance costs. For people more interested in indoor air quality, running the HVAC fan 24/7 is the superior choice. 

If you have a drafty home or live in an area with extreme temperatures, you may want to leave the fan running to help even the temperature. However, If you’re only interested in keeping your home comfortable, either mode will work fine. 

Not sure what’s best for your home? You can always consult with a local HVAC professional. They can help you determine the best settings for your HVAC system based on your climate and the efficiency of your system.

Read: Should An HVAC Zone Damper Bleed Air?

Running HVAC 24/7: Things To Keep in Mind

If you’re running your HVAC 24/7, there are a few things you’ll need to keep in mind:

  • Make sure that your system is sized correctly for your space. If it’s too small, it won’t be able to keep up with the demand. 
  • You’ll need to monitor your system closely and perform regular maintenance to keep it running efficiently. 
  • Be prepared for increased energy costs.


So, is it really OK to run your HVAC fan all day? Yes, it is! As a matter of fact, many experts recommend keeping the fan on. HVAC fans circulate the air in your home and can help to keep your home cool in the summer and warm in the winter. So, if you’re comfortable, go ahead and keep that fan running all day long!