Should You Use the On or Auto Thermostat Setting?

The common thermostat is a relatively simple device. Even the modern programmable models, with all their bells and whistles, in most cases aren’t that hard to figure out. However, many homeowners remain puzzled by the thermostat setting for fan operation. Should it be set to “on” or “auto”? We’ll try to walk you through the various pros and cons of thermostat fan settings.

The “on” setting means the fan that pushes conditioned air through your house is always on, whether any cooling or heating is happening or not. The “auto” setting, on the other hand, only runs the fan when the thermostat temperature setting signals the A/C, heat pump or furnace to create warm or cold air.

Many HVAC experts recommend the default “auto” setting for a variety or reasons, though the “on” setting does have its own advantages.

Advantages of the Auto Setting

• If your HVAC fan isn’t running all the time, you’ll save energy on fan operation plus the blower component won’t undergo as much stress. It should last longer before repair or replacement is required.
• You won’t have to change the air filter as often. It will stay clean longer, adding to system efficiency and performance.
• Ductwork receives less stress when air isn’t constantly blowing through the ducts. Continuous air movement is a factor in duct leakage.
• Non-continuous fan operation means less opportunity for dirty air to sneak into ductwork in the attic, crawl space or garage, and circulate with household air.
• The “auto” setting isn’t as noisy as the “on” setting, since the fan is silent for much of the time.
• The system will dehumidify better in the cooling mode if the fan is set to “auto”.

Advantages of the ‘On’ Fan Setting

• If you have an effective air filter for your HVAC system, you’ll get cleaner air when the fan is circulating air 24/7.
• Full-time fan operation in some cases is needed for proper air circulation but you run the risk of higher humidity levels in the cooling mode.

For more information on the best thermostat setting for your Coastal Bend home, for both comfort and efficiency, please contact us at CCAC, Inc.

Our goal is to help educate our customers in Corpus Christi, Texas about energy and home comfort issues (specific to HVAC systems). For more information about thermostat settings and other HVAC topics, download our free Home Comfort Guide or call us at 361-678-2495.

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