Is There An Advantage To Setting My Thermostat Fan To On So The Fan Runs Constantly?

Setting your thermostat fan to "On" so that the fan runs constantly can have both advantages and disadvantages. Let's explore both sides to help you make an informed decision based on your preferences and needs:


  1. Improved Air Circulation: Keeping the fan running constantly helps distribute air more evenly throughout your home. This can lead to a more consistent temperature in different areas and reduce hot or cold spots.

  2. Filtration and Air Quality: A constantly running fan helps filter and circulate the air, which can improve indoor air quality by trapping and removing dust, allergens, and pollutants from the air. This is particularly beneficial for people with allergies or respiratory issues.

  3. Humidity Control: The fan running continuously can also aid in maintaining a more consistent level of humidity throughout your home, which can contribute to comfort and prevent mold growth in humid climates.

  4. Reduced Energy Spikes: With the fan constantly circulating air, your HVAC system might not have to work as hard during the cooling or heating cycles. This can lead to more consistent energy usage and potentially reduce the strain on your HVAC equipment, which might extend its lifespan.


  1. Increased Energy Usage: Running the fan constantly can result in higher energy consumption, as the fan requires electricity to operate. This could lead to slightly higher utility bills.

  2. Noise: Depending on the location of your thermostat and the design of your HVAC system, the constant noise from the fan might become a nuisance, especially during quiet hours or when you're trying to sleep.

  3. Reduced Efficiency: While the constant fan circulation might help with temperature balance, it can also hinder the efficiency of your HVAC system's cooling or heating cycles. The system might not be able to dehumidify or heat/cool your home as efficiently when the fan is always running.

  4. Comfort Challenges: In certain weather conditions, like extremely hot or cold days, a constantly running fan might not provide the desired comfort. The air blowing from the vents might not be the right temperature to match the set thermostat temperature.


Ultimately, the decision to keep your thermostat fan set to "On" or "Auto" depends on your priorities and comfort preferences. If you value improved air circulation, air quality, and more even temperatures, running the fan constantly could be beneficial. However, if energy efficiency and lower utility bills are more important to you, using the "Auto" setting might be a better choice.

A potential compromise could be using the constant fan mode during specific times, such as during days with high pollen counts or when you're using the fireplace, and then switching back to "Auto" mode during times when you're not at home or when energy efficiency is a higher priority.

In any case, it's a good idea to monitor your energy usage and comfort levels to determine the best setting for your specific situation.

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