HVAC fan controlMost traditional heating and AC thermostats have separate settings for heating, air conditioning, and the fan. The heating and AC settings are straightforward.

During the cold months, when you want to warm the house, you set the system to heat. In the summer when you want to cool, you set it to cool. During periods of the year when you need neither, you can simply set the thermostat to OFF to conserve energy.

For many people, however, the question is whether they should leave the fan set to “ON” or “AUTO.”   The truth is, there is no right or wrong answer.  Each option has its own pros and cons.

Setting the HVAC fan to ON

When set to ON, the fan will keep running 24/7, regardless of the heating or cooling setting.

The biggest advantage of this is that air will be pulled through your filtration system, thereby cleaning it so you’ll be breathing cleaner air around the clock. Keeping the fan ON circulates the air through your home so you don’t wind up with some rooms or areas that are warmer or cooler than others. Fewer starts and stops can also prolong the fan’s life.

On the flip side, keeping the HVAC fan ON 24/7 can be very expensive. Running the fan every second of every day can cost $50 or more depending on the HVAC system – that’s $600 per year. Constantly circulating your indoor air can also cause the HVAC system’s filter to lose efficiency much faster as dust, pet dander and other contaminants accumulate on it.  The can lead to more frequent filter replacements and ultimately higher costs. Lastly, keeping the fan ON in winter can also make the house feel colder.

Setting the fan to AUTO

When the HVAC fan is set to AUTO, it only runs when necessary to heat or cool your home to the desired temperature.

As you’d guess, this results in less energy usage because the fan will run for fewer hours and at lower speeds.  As a result, you’ll need to clean or replace your filters less frequently which further reduces the overall cost of heating and cooling your home.

On the other hand, during periods when the fan isn’t running, your indoor air may not feel as fresh – a condition that some refer to as a “stuffy” feeling. The lack of constant air movement can also cause some rooms to be warmer or cooler than others depending on their proximity to the thermostat. Finally, frequent starts and stops can cause more wear and tear on the fan which can lessen its life expectancy.

The choice is yours

When it comes to the question of setting your HVAC fan to ON or AUTO, the answer comes down to personal preference.  If you’d rather spend more and get the most comfort possible, keep the fan ON. But if you’re keen on maximizing energy efficiency, then AUTO makes more sense.  Most people alternate between the ON and AUTO settings throughout the year.

If neither setting seems to deliver the results you want, the problem may be more than the fan setting.  If it’s been awhile since you’ve had your system inspected, scheduling an HVAC tune-up is the logical first step.  It could also be a problem with the thermostat itself.

At Metro Energy Savers, we recommend replacing old, inefficient thermostats with a “Smart” thermostat.  Call or click the link for more information about our thermostat installation services in the greater Fort Worth area.