Answered: Should My Thermostat Be on Auto or Fan?

When the weather begins to cool off, you might be concerned about how you’ll make the most of your heating and cooling. After all, HVAC expenses can make up a large chunk of your monthly electric bill. To figure out new ways to save, some owners look closer at their thermostat. Maybe there’s a setting they could use to increase efficiency?

The bulk of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what can the fan setting provide for an HVAC system? This guide should help. We’ll review what exactly the fan setting is and whether you can use it to reduce costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting signifies that the system’s blower fan keeps running. A few furnaces will generate heat at a low level with this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will turn on the fan during a heating or cooling cycle and switch it off after the cycle is complete.

There are advantages and disadvantages to using the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort preferences.

Advantages to trying the Fan/On setting:

• You can keep the temperature in every room more consistent by allowing the fan to keep running.
• Indoor air quality will be highest since steady airflow will keep forcing airborne particles into the air filter.
• A smaller number of start-stop cycles for the blower fan helps expand its life span. As the air handler is typically part of the furnace, this means you could minimize the risk of needing furnace repair.

Disadvantages to switching to the Fan/On setting:

• A constant fan can raise your energy costs by a small margin.
• Continuous airflow can clog your air filter soon, increasing the frequency you’ll need to replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air will sometimes persist in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may draw this warm air into the rest of your home, compelling the HVAC system to run longer to keep up with the set temperature. In severe heat, this can result in needing AC repair more often as wear and tear grows.

The opposite can take place in the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually flow into the rest of your home. Leaving the fan setting on could pull more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to figure out if you should use the fan/on setting, remember that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may be best for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on should help to increase indoor air quality, helping your family breathe easier.

Your home deals with hot and cold spots. All kinds of homes deal with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting can help lessen these changes by steadily refreshing each room’s supply of air.