How to Replace Your HVAC Air Filter

Replacing your HVAC air filter is the single highest-value DIY maintenance task in your home. A clean filter keeps your system efficient, lowers energy bills, and improves air quality.

How often?

• 1-inch standard filters: every 1–3 months
• 4-inch+ pleated filters: every 6–9 months
• Sooner if: you have pets, allergies, or live in a dusty area

What you need

• The correct size filter (printed on the side of the old one, e.g. 16x25x1)
• A step stool if the unit is wall-mounted

Steps

1. Turn the system off at the thermostat so the blower doesn't kick on.
2. Locate the filter — usually at the return air vent or inside the air handler.
3. Note the airflow arrow on the old filter's frame. The arrow points toward the furnace/AC.
4. Slide the old filter out and slide the new one in with the arrow pointing the same way.
5. Close and latch the filter cover door tightly.

When to call a pro

If you find heavy dust inside the unit, damaged ductwork, or unusual noises, don't open the motor housing — call a licensed HVAC technician.