Thermostat Settings – On or Auto?


Heat, Cool, and Off are the straightforward settings of one switch on many thermostats. But what about the other switch? Should you choose On, or Auto? What’s the difference?

On means the fan is going to run continuously, 24/7. Auto means that the fan will only run while the system is actively heating or cooling the air. The setting you use can depend on a number of factors, and ultimately your personal preference. Here’s some basic information to get you thinking about a strategy that works best for you and your family.

On Setting


More air circulation means cleaner air. Since the air is running through a filter, this setting may be better for family members that suffer from allergies or asthma. Leaving it On means less starts and stops for the fan, and may prolong the life of your fan.


Since the air is getting filtered more, you’ll need to check and replace your filter more often. The On setting is going to be more expensive. You will probably notice a difference in your monthly energy bill. In the winter it might feel like cold air is coming through the vent. It only seems cold compared to your body temperature. It’s not cold air. It’s the temperature set on your thermostat, and it’s not actively being heated.



The fan runs less often, as it will only run while the air is actively being heated or cooled. This is more energy efficient and may result in a lower monthly energy bill. Auto is the setting that most homeowners use.


More starts and stops for your fan may shorten the life of your fan in the long run. In general you’ll get less air circulation in your home if you leave it on the Auto setting.

Try a combination of both:
Set it to On when you are at home during the day. Then, turn it to Auto at night or when you are away. With this strategy you will enjoy the benefits of better air circulation while you are home, and the cost saving of only using the fan when the systems needs to while you are sleeping, or away.

Trouth is a local HVAC contractor that provides service to residents of Sulphur, Louisiana and nearby areas. Call 337-527-8683 today to consult with the experts at Trouth to decide which setting best suits you and your family. Or, request service online.

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Call us at 337-527-8683!

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