Once 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 costs can add up to a large chunk of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners take a closer look at their thermostat. Could there be a setting they should use to boost efficiency?
Most thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what will the fan setting offer for the HVAC system? This guide can help. We’ll review what exactly the fan setting is and when you can use it to cut costs over the summer or winter.
What Is the Fan Setting on My Thermostat?
For the bulk of thermostats, the fan setting signifies that the HVAC blower fan keeps running. Some furnaces will operate at a low level with this setting, but in most cases heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan through a heating or cooling cycle and turn it off after the cycle is finished.
There are benefits and drawbacks to using the fan setting on your thermostat, and what's ideal will depend on your unique comfort needs.
Advantages to using the Fan/On setting:
- You can keep the temperature in each room more consistent by allowing the fan to keep running.
- Indoor air quality will be highest as steady airflow will keep forcing airborne particles through the air filter.
- A smaller amount of start-stop cycles for the HVAC fan helps expand its life span. Since the air handler is often a component of the furnace, this means you could minimize the risk of needing furnace repair.
Disadvantages to switching to the Fan/On setting:
- A continuous fan can increase your energy costs by a small margin.
- Continuous airflow could clog your air filter up more quickly, 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 will sometimes persist in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system can pull this warm air into the rest of your home, forcing the HVAC system to run longer to keep up with the set temperature. In severe heat, this could result in needing AC repair more regularly as wear and tear gets worse.
The reverse can happen over the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually drift into the rest of your home. Keeping the fan on could draw more cold air upward, increasing the amount of heating you need to remain warm.
If you’re still trying to decide if you should use the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on might work for you if:
Someone in your household has allergies. Allergies and other 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 has hot and cold spots. All kinds of homes wrestle with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting should help limit these changes by constantly refreshing each room’s airflow.