How to Change a Furnace Filter

Turn off your furnace, locate the filter compartment, slide out the old filter, and insert the new one with airflow arrows pointing toward the furnace.

1. Kill the Power First. Switch off your furnace at the thermostat and the main power switch. This prevents the system from running while you work and protects the motor from debris. Wait a few minutes for any moving parts to stop completely.
2. Hunt Down Your Filter. Find the filter slot, typically located where the return air duct connects to the furnace or in the blower compartment. It may be behind a removable panel or door. Some filters are housed in a separate return air grille on the wall or ceiling.
3. Slide Out the Dirty One. Pull out the existing filter carefully. Note which direction the airflow arrows point before removing it completely. Dirty filters can be dusty, so have a vacuum or trash bag ready. Check the filter size printed on the frame.
4. Arrows Point Home. Slide the new filter into place with the airflow arrows pointing toward the furnace unit. The arrows should point in the same direction as the old filter. Make sure the filter fits snugly with no gaps around the edges that would allow air to bypass it.
5. Flip It Back On. Replace any panels you removed, then turn the furnace back on at both the power switch and thermostat. Listen for normal operation and check that air is flowing properly through your vents.