When the weather starts to cool off, you might be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC expenses can make up a big portion of your monthly electric bill. To try and find ways to save, some people look closely at their thermostats. Is there a setting they can use to increase efficiency?

The bulk of thermostats includes both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what can the fan setting offer for an HVAC system? This guide will help. We’ll review just what the fan setting is and when you can use it to reduce costs during the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting indicates that the air handler’s blower fan remains on. Certain furnaces will run at a low level in this setting, but in most cases, heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will turn on the fan during a heating or cooling cycle and turn it off after the cycle is over.

There are benefits and drawbacks to trying the fan setting on your thermostat, and whether you do or don’t will depend on your distinct comfort needs.

Advantages to trying the Fan/On setting:
  • You can keep the temperature in each room more balanced by permitting the fan to keep circulating air.
  • The indoor air quality will be highest because steady airflow will keep forcing airborne contaminants into the air filter.
  • A smaller number of start-stop cycles for the blower fan helps lengthen its life span. Since the air handler is usually connected to the furnace, this means you can minimize the risk of needing furnace repair.
Drawbacks to switching to the Fan/On setting:
  • A continuous fan could increase your energy costs by a small margin.
  • Constant airflow may clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

Should My Thermostat Be on Fan or Auto in Summer/Winter

During the summer, warm air can linger in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system might gradually move this warm air into the rest of your home, compelling the HVAC system to work harder to keep up with the set temperature. In serious heat, this may result in needing AC repair more regularly as wear and tear grow.

The opposite can occur over the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually drift into the rest of your home. Keeping the fan on will sometimes pull more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should switch to the fan/on the setting, keep in mind that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on might be ideal for you if:

Someone in your household deals with allergies. Allergies and similar respiratory conditions can be stressful for the family. Leaving the fan on is more likely to increase indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. All kinds of homes deal with difficult hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting can help limit these changes by steadily refreshing each room’s ventilation.

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