Solved: Should My Thermostat Be on Fan or Auto?

Once the weather is cooling off, you may be thinking about how you’ll prepare your heating and cooling. After all, HVAC bills routinely add up to a large chunk of your monthly electric bill. To figure out new ways to reduce costs, some homeowners look closely at their thermostat. Is there a setting they can use to increase efficiency?

The majority of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what will the fan setting offer for your HVAC system? This guide will help. We’ll walk through just what the fan setting is and how you can use it to cut costs during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting means that the HVAC blower fan remains on. A few furnaces can generate heat at a low level in this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, 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 using the fan setting on your thermostat, and what’s ideal {will|can|should]] depend on your distinct comfort needs.

Advantages to using the Fan/On setting:

• You can keep the temperature in each room more uniform by enabling the fan to keep generating airflow.
• Indoor air quality can increase because continuous airflow will keep passing airborne pollutants into the air filter.
• A smaller number of start-stop cycles for the blower fan helps extend its life span. Because the air handler is often part of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to using the Fan/On setting:

• A continuous fan could increase your energy expenses 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.

Which Setting for My Thermostat? Fan or Auto in Summer/Winter

In the summer, warm air may stick around in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system may draw this warm air into the rest of your home, compelling the HVAC system to run longer to maintain the set temperature. In severe heat, this can lead to needing AC repair more quickly as wear and tear grows.

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

If you’re still trying to decide if you should try the fan/on setting, don’t forget that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on could be best for you if:

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

Your home deals with hot and cold spots. Many homes wrestle with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting can help minimize these changes by consistently refreshing each room’s airflow.