The HVAC thermostat in your home provides two options for running the AC fan. In most cases, you have a choice of “Fan On” and “Fan Auto.” The “Fan On” selection will run the system fan at all times, even when the air conditioning or furnace mode cycles off. “Fan Auto,” conversely, starts the fan only when the system’s cooling or heating cycle begins, then shuts it down each time those functions cycle off.
At first glance, “Fan On” may seem like the best option for your AC fan. Here are some advantages of keeping the AC fan running 24/7:
- Less wear and tear on the fan motor when it runs nonstop versus repeatedly turning on and off.
- Continuous circulation of air through the system filter may benefit indoor air quality.
- Temperature control may be more consistent in certain houses if the fan continues circulating air at all times, even as AC and furnace functions cycle on and off.
“Fan Auto” may actually be the preferred setting, however, when you consider these facts:
- Indoor humidity actually increases when the system fan runs nonstop. Humidity inside a home is an important aspect of comfort, particularly during air-conditioning season. The indoor evaporator coil in a central AC condenses water vapor from indoor air, which drains away from the coil when the fan cycles off. If the unit is in nonstop “Fan On” mode, however, residual moisture in the coil is blown back into the ductwork instead of draining away, making the indoor environment more humid and harder to cool.
- Electrical costs are higher. The large HVAC blower fan typically uses about 500 watts of electricity. Continuous 24/7 operation of the system fan consumes nearly the same amount of power as a small refrigerator.
For more information about the benefits and drawbacks of AC fan settings, talk to the HVAC professionals at Energy 1 Heating & Air Conditioning.
Energy 1 Heating & Air Conditioning
1 (440) 246-5440
Serving the Lorain, OH Area