Fan On vs. Auto: Which One Should You Choose When Setting Your Thermostat?

July 16, 2015

The trusty thermostat controls the basic cooling, heating and airflow functions of the HVAC system in your Des Moines area home. While the degree number you choose when setting your thermostat controls your home's temperature, the fan settings "on" and "auto" control the blower in between the "cool" and "heat" modes. Keep reading to learn which fan setting serves your needs for better comfort, indoor air quality and your energy budget goals.

Setting Your Thermostat When the fan is set to "on," the HVAC blower is going to run continuously, whether or not the cooling or heating systems are engaged. If you set the thermostat fan mode to "auto," the blower will turn on and off in time with the cooling and heating systems. There are advantages and disadvantages to both fan settings. It really depends on your comfort preferences and energy budget goals. Here's why:

  • Indoor air quality: Perhaps the biggest perk to running the fan continuously in the "on" setting is better indoor air quality. With continuous airflow, a substantially greater number of airborne contaminants are captured by the HVAC system's air filter. Just remember to change your air filter regularly.
  • Energy budget goals: Keep in mind that if you run the fan setting in the "on" mode, the continuous operation of your blower motor will increase your energy bills. If the air filter isn't changed or cleaned on a more frequent schedule due to the continuous airflow, the HVAC system uses more energy to pull airflow through a dirty or clogged filter.
For more tips on setting your thermostat for the best comfort and efficiency results, contact Lozier Heating & Cooling today. We've served Des Moines area homeowners for more than 100 years. Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems). Credit/Copyright Attribution: "Daniel Hodac/Shutterstock"