Close-Up of a thermostat's fan settings

Should An HVAC Fan Run Constantly?

Energy Savings

There are many homeowners who are not familiar with HVAC units, and often learn the in and outs of them only when it is too late, and when they are about to replace one because of their lack of knowledge about upkeep and how to properly run them. One of the most common questions that HVAC companies receive is customers asking whether they should set their units to fan or auto, or to keep them continuously running. This is a topic that has both pros and cons, and both will be explored here.

Pros to Continuous Fan Setting

When the unit is set to the “on” setting, you are instructing it to stay running 24 hours a day, every day of the week. This is regardless of the heating or cooling setting. A few positives to this feature are:

  • By keeping the fan on, a more even distribution of circulation of air is achieved, whether it be heating or cooling and is good for cold or hot spots in the house such as above a garage or in a certain bedroom.
  • Having less repeated starting and stopping of the unit can reduce stress put on it, and can increase its lifespan in the long run.
  • Keeping the unit fan on can lead to cleaner air inside because the air is being put through the filtration system/UV light system. People with allergies find this most beneficial.

Cons to Continuous Fan Setting

There are also downsides to keeping your HVAC fan on the continuous setting. While it can be more energy efficient at times, the constant running could cost you hundreds of dollars more every year.

  • A homeowner who has a 500-watt fan could be hiking up their energy bill around 50 more dollars a month. This 500-watt fan is basically equivalent to using around as much energy as a refrigerator over the span of a year.
  • If kept running in the hot summer months, the fan will be blowing hot air all over your house. In turn, this necessitates the need to run the AC much more often to combat the extra heat.
  • The same goes for running the fan in the winter months. More cold air is circulated throughout the house causing the need to hike your heat up.

Setting Your HVAC Fan to Auto

Putting your fan on the auto mode gives the unit the ability to decide when the fan needs to be engaged and is much more cost effective and works with the heating and cooling system so that the fan runs at the slowest speed and for the least amount of time that it is needed. This saves on wear and tear of the unit, and therefore can help make your furnace last longer. This method is not quite the answer many are looking for; with this setting there is less even distribution of heating and cooling. And once the thermostat has done its job, the fan will stop moving air to other areas throughout the home. However, setting your fan to auto can help you save money and wear on your unit.

If you’re still concerned about lack of circulation, one may want to consider upgrading to newer grade thermostats that now have a “circulate” option- this will allow the fan to be set to the “on” option for a certain amount of time every hour. This in turn can lower bills and give an increased comfort level throughout the home.

For more information about running your HVAC, or to consult a professional about a repair or upgrade, contact AirOne Heating and Air Conditioning Repair, located in San Marcos, TX.

Photo credit: CORGI HomePlan on Visualhunt / CC BY

Menu