Should You Set Your Thermostat’s Fan Setting to “ON” or “AUTO”?

Have you been keeping your thermostat fan set to “ON” for your air conditioning or heating? You may be costing yourself big bucks.

Let’s break down the difference between keeping your fan “ON” versus “AUTO.”

The thermostat fan setting: ON or AUTO?

Here’s what each setting means:

AUTO: This means your furnace or air conditioning fan will only run until the temperature you’ve set on the thermostat has been reached, and then it will stop.

ON: This means your furnace or air conditioning fan will run CONSTANTLY, even if the desired temperature has been reached.

Why you shouldn’t use the fan’s ON setting

1) Poor humidity 
If the fan is constantly running, the AC unit won’t be able to regulate and dehumidify your home as well as it could be. 

2) Higher risk of damage to the fan 
A constantly-running fan could shorten the motor’s life and cause it to break down. That means repair or replacement costs.

3) Higher electric bill
Because the fan will run constantly, your electric bill will be higher. 

The electric bill increase is negligible if you have a high-efficiency ECM blower, which is like a dimmer switch: it precisely ramps up or down depending on your comfort needs., But, still, most homeowner have PSC single-speed motor, which will was a lot of money if left running 24/7.

Regardless of the blower type, you’ll lose more air out of air duct leaks, which are more common than you think. According to Energy Vanguard, a study showed that most air ducts leak up to 12% of the air going into a heating or cooling unit and 10% of the air coming out.

When should I keep the thermostat fan ON instead of AUTO?

Despite all that, there are a few reasons why you may want to set the fan to ON at times.

1) While cleaning or vacuuming
When you clean the house, dust kicks up. If you set the thermostat fan to “ON” when you clean, the return ducts will suck up excess dust in the air and prevent it from settling back down.

2) Make cleaner air for allergy sufferers
If you or your family members have bad allergies from home pollutants, it may be worth it to run your fan and help clear the air. However, when you aren’t home, you should still set your thermostat fan back to AUTO.

If you have questions about or problems with your thermostat, furnace, air conditioning, air ducts, or anything else, contact On Time Service Pros

We serve Hastings, Apple Valley, Burnsville, Cottage Grove, Eagan, Woodbury, Lakeville, Rosemount, Stillwater, the Twin Cities and more with quality HVAC, plumbing and electrical service.


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