July 30, 2015

Almost all thermostats come with the “on” and “auto” fan settings. A deeper understanding of both settings helps you know the right time to use each.

The “On” and “Auto” Setting

When the thermostat is set to “auto,” the fan only works during the heating and cooling cycles. Once the thermostat’s temperature is reached, it stops running.

Setting the thermostat to “on” makes the fan run continuously, regardless of whether or not your home’s cooling and heating cycles are on or off.

Pros of the “Auto” Setting

The “auto” setting uses less energy than the “on” setting because there are time gaps when the fan isn’t running. The filter lasts longer because it doesn’t work constantly, and the system also dehumidifies the air better.

On the other hand, the fan makes many stops and starts, making it wear over time. The setting also allows for more hot and cold spots.

Pros of the “On” Setting

The “on” setting always cycles air through the filter, allowing more allergens to be removed. This is highly beneficial for allergy and asthma sufferers. This setting also allows air to be circulated more evenly throughout your home, which helps the fan last longer due to fewer stops and starts.

“On” Setting Cons

The main disadvantage is that it increases your monthly utility bills due to the fan running around the clock. On this setting, you’ll have to replace the air filter more frequently since the fan continually pulls air through it, causing clogging over a relatively short period of time. The blower will also need maintenance more often.

In the winter, this setting can make cold air come out of the vents when the furnace is off. Another significant disadvantage is that humid air sucked in by your air conditioner is circulated back into your home’s air.

While the “on” setting gives you extra filtration and comfort benefits, it has more disadvantages than advantages so it’s only beneficial for short periods of time.

For more information on setting the thermostat, contact us at Wolff Mechanical. We’ve served the central Arizona area for over 20 years.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems).

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