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Should I Select On or Auto on My Thermostat?

Senior woman saving energy by dressing warm and adjusting her thermostat.

Great question! On most thermostats, there are two temperature options: Heat and Cool. Nearby, you can choose between On or Auto for your fan setting. On tells your HVAC unit to run its fans all the time, even when the air isn’t being heated or cooled. Auto means the fan only runs when your air is being treated. Each option has its advantages and disadvantages, and our team at Dean’s Shop Inc. is happy to help you select what works best for you if you’re still having trouble deciding after reading below.

On Setting

The Advantages

Your air is constantly circulated. This means more particles are caught by the filter, and mold has a less comfortable environment where to grow. If someone in your household suffers from allergies, this option is of great benefit. Also, fewer stops and starts for the fan means it may last longer.

The Disadvantages

More circulation means the air filter needs cleaning or replacing more often. It also uses more electricity than Auto, which means you are paying more at the end of each month. During colder weather, the On setting might be annoying, since the air keeps blowing when the heat is off.

Auto Setting

The Advantages

Auto is the more popular setting. Since the fan only blows when heating or cooling the air, it uses much less electricity than On. With this setting, you’re using your energy more efficiently, resulting in a lower monthly energy bill.

The Disadvantages

The starting-and-stopping mechanism is hard on your fan after awhile. It may decrease its longevity, eventually leading to replacement. You’ll also get less air circulation.

Final Recommendations

It might be a good idea to try a combination of both settings. If you like the ventilation feature of the On setting, keep it set to On only when you’re home, then set it to Auto at night. This way, you’re still getting the air filtration you desire without overspending on electricity.

For more information on HVAC systems, give Dean’s Shop Inc. a call at 512-353-4770. We are located just around the corner from you here in San Marcos, TX. If you ever need HVAC advice, installations, or maintenance, we’re your team.


Ballard Natural Gas Services is proud to offer services to Seattle, Shoreline, West Seattle, Capitol Hill, Lake Forest Park, Richmond Beach, Bellevue, Mercer Island, Edmonds, Mountlake Terrace and the surrounding communities. Call us at 206-784-8101 or request service online today!

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