How often should you change your air filter?

For most homes, the air filter should be changed every 1 to 3 months. Check it once a month, and if it looks gray or clogged, swap it out even if three months haven't passed.

The right timing depends on your filter and your house. Thin fiberglass filters often need changing about once a month. Thicker pleated filters can often last 2 or 3 months. You may need to go sooner if you have pets, someone in the home has allergies, there is dust from a remodel, or the system runs nonstop during a long Chattanooga summer.

Why it matters: a dirty filter makes your heating and cooling system work harder to pull air through. That can raise energy use and add wear to the equipment. Federal energy guidance suggests checking the filter every month and changing it at least every three months.

Changing it is simple. Turn the system off and find the filter slot, which is often near a large return vent or the indoor unit. Note the size printed on the edge of the old filter. Slide the new one in with the airflow arrow pointing toward the unit. Write the date on the frame with a marker so you know when you last changed it.

Fortress changes the air filter on its Spring Refresh and Fall Prep visits. If the system itself isn't heating or cooling right, that is a job for a licensed technician, not a handyman.