Los Angeles HVAC: Auto or Fan On? Learn Which Thermostat Setting Is Best for Your Home

Los Angeles HVAC: Auto or Fan On? Learn Which Thermostat Setting Is Best for Your Home

Many of us take our home thermostats for granted. We set the temperature we want and then forget about it. But you can save money on utility bills while improving your comfort if you pay closer attention to thermostat settings. For example, your choice with the fan setting – “on” or “auto” – can make a meaningful difference in energy use and home comfort.

What’s the Difference?

Any forced-air HVAC system has two separate modes of operation: the equipment that creates the heating or cooling, and the system with a motor, fan and ducts that circulates the air throughout your home. There’s some overlap with A/C and heat pump systems, but that’s basically it.

The fan setting on the thermostat controls the second part of that equation: the air distribution. If it’s set to “auto,” the fan only operates when the HVAC equipment is producing cool or warm air. In the “on” mode, the fan operates all the time, regardless of whether heating or cooling is happening.

Some HVAC experts swear by the 24/7 fan operation (“on”), but most recommend using “auto” for several reasons.

Why “Auto” Is Better

• If your A/C or heat pump is oversized, which is quite likely, it will cycle on and off frequently. The bigger capacity cools the home quickly and then shuts down till it needs to come on again. During the “off” cycle, residual moisture from the cooling process will be left on the evaporator coil. If the fan continues to operate during this time, it will absorb that moisture and redistribute it into the household air. Your A/C will have to work harder to remove that moisture a second time.
• Running the fan continuously uses more energy than if it stops operating when the home isn’t being heated or cooled.
• If your ductwork is leaking, the 24/7 operation will draw more humid and dirty air into the duct system, which then gets circulated in your home.

For some advice on the proper thermostat settings in your home, please contact us at Air-Tro Inc. We’ve been keeping Southern California cool since 1969.

Our goal is to help educate our customers in the greater Los Angeles, California area about energy and home comfort issues (specific to HVAC systems).

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