Setting Your Thermostat: Is Fan On or Auto Best?

Setting Your Thermostat: Is Fan On or Auto Best?Setting your thermostat fan control can be somewhat confusing. Is it better to leave the fan “on” or set it on “auto?” Leaving the fan in the on position and operating continuously may seem logical to increase comfort and reduce A/C energy consumption, but it can actually erode comfort and cost more in the long run. Learning the purpose of each setting and its pros and cons can help clarify which option is best.

Auto Setting

When the fan is set on auto, it starts and stops in tandem with the A/C’s evaporator coil whenever cooling is called for by the thermostat. Running the fan on auto is the most energy efficient option if you have a single-speed air handler, and you won’t have to change the air filter as often. The only drawback is there’s no air circulation for a brief period during each cycle, so the living space may start to feel stuffy before the A/C and fan start up again.

On Setting

When the fan setting is in the on position, it runs continuously, even when the air conditioner cycles off and stops producing cool air. It’s okay to use the on setting for short periods to boost air filtration, but leaving it running isn’t recommended unless the A/C has a variable-speed air handler. Disadvantages of leaving the fan in the on position include the following:

  • The average HVAC fan motor is 500 watts. It consumes roughly the same amount of energy as a refrigerator. Running it nonstop will increase your monthly utility bills.
  • When the cooling coils cycles off, the ducts quickly fill with warm, humid air. With the fan on, all that heat and moisture gets circulated through the home. This puts unnecessary strain on the air conditioner and makes effective humidification difficult.
  • Operating the fan nonstop can also increase your cooling costs, since the A/C has to run for longer periods to compensate for recirculated heat and humidity.

Please note that if you’re using an air filter with a high MERV, you may need to run your fan continuously on a seasonal basis to effectively reduce indoor air pollutants. If you’re not sure, consult your HVAC professional for assistance.

For expert advice on setting your thermostat correctly to maximize comfort and energy savings in your Peachtree City home, contact the pros at Powers Heating & Air.

Our goal is to help educate our customers in Peachtree City, Georgia and surrounding areas about energy and home comfort issues (specific to HVAC systems).

Credit/Copyright Attribution: “Heymo/Shutterstock”