Are you standing in front of your wall control right now, wondering if your thermostat should be set to “On” or “Auto”?
For 95% of homeowners, your thermostat fan should be set to “Auto.” Setting your fan to “Auto” is the most energy-efficient choice. It ensures the blower fan only runs when actively cooling or heating your home.
Leaving the switch set to “On” forces the fan motor to run 24 hours a day, 7 days a week, which will noticeably increase your monthly electricity bill and force you to buy air filters much more frequently.
Understanding the basic difference between auto and on for ac and heating systems comes down to control. “Auto” ties the fan to the temperature cycle, while “On” forces continuous air circulation regardless of the temperature.
Here is a breakdown of exactly when you should use each setting.
When to Use the “Auto” Setting (The Everyday Choice)
As the experts at Siemer Heating, Cooling & Plumbing, we highly recommend making “Auto” your default, everyday setting. It is the ultimate “set it and forget it” approach to home comfort.
You should leave your system on “Auto” to take advantage of:
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Lower Utility Bills:
According to ENERGY STAR®, heating and cooling account for nearly half of your annual home energy bill. Only running the fan when necessary is the easiest way to cut those costs.
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Longer Filter Life:
Your HVAC filter only traps dust when air is moving through it. By giving the system a break between cycles, your filter will last much longer.
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Winter Comfort:
Homeowners often debate whether to use the heater auto or fan setting in the winter. If you set it to “On,” the fan will blow room-temperature air when the furnace burners are off, which feels like a cold, uncomfortable draft against your skin. “Auto” ensures only perfectly heated air comes out of your vents.
By defaulting to the “Auto” setting, you strike the perfect balance between keeping your home comfortable and keeping your monthly energy costs as low as possible.
When to Use the “On” Setting (The Strategic Choice)
While “Auto” is the best everyday choice, the “On” setting still serves a very important purpose. Running the fan continuously provides excellent air circulation, but you have to be willing to accept higher utility bills and more frequent filter changes.
Instead of leaving it on 24/7, we recommend temporarily switching your thermostat to “On” for these specific use cases:
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During Heavy Cleaning:
Flip the fan to “On” while you are dusting, sweeping, or vacuuming. The continuous suction will pull all those kicked-up allergens directly into your HVAC filter.
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When Allergies are Peaking:
If someone in your home suffers from severe spring allergies or asthma, running the fan continuously can act as a whole-house air purifier (just be ready to change the filter monthly).
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To Balance Hot and Cold Spots:
If your upstairs is baking while your downstairs is freezing, temporarily turning the fan to “On” will constantly mix the air in the house, helping to even out the temperature.
Once you have cleared the air or balanced the temperatures in your home, simply flip the switch back to “Auto” to resume your normal, energy-saving schedule.
Call Your Highland HVAC Experts Today
Understanding the intricacies of your thermostat ensures you get the most value out of your heating and cooling equipment. If you are struggling with hot and cold spots, poor indoor air quality, or a thermostat that just won’t cooperate, we can help!
Our professionals at Siemer Heating, Cooling & Plumbing stand ready to offer practical, money-saving solutions for your home. Call us today or contact us online to schedule a service!