How to Replace Your HVAC Filter
Replacing your HVAC filter is one of the simplest and most impactful maintenance tasks you can do for your home. A clean filter improves air quality, reduces energy bills, and extends the life of your heating and cooling system. Most homeowners can complete this task in under 15 minutes.
What You'll Need
Supplies
- •Replacement HVAC filter (check your current filter for size, e.g., 20x25x1)($15-25)
- •Foam weatherstripping tape (if filter fits loosely)(optional)($3-5)
Tools
- •Step stool or small ladder (if filter is in ceiling or high wall)(optional)
- •Permanent marker (to write install date on filter)(optional)
Step-by-Step Instructions
Turn off your HVAC system
Switch your thermostat to the OFF position before removing the filter. This prevents unfiltered air from circulating through your system and protects the blower motor from debris.
Pro Tip: Some systems have a dedicated power switch on the unit itself. If yours does, turn that off too for added safety.
Locate your filter
Find the filter compartment, which is typically located in the return air duct near the furnace or air handler, or behind a return air grille on a wall or ceiling. On some systems, the filter slides into a slot on the side of the unit.
Pro Tip: If you have never changed the filter before, look for a 1-inch wide slot near the blower compartment. Many units have a small label or arrow indicating the filter location.
Remove the old filter
Slide the old filter out of its slot. Note the size printed on the frame (e.g., 20x25x1 or 16x20x4). Also look for an arrow on the frame showing the airflow direction -- you will need to install the new filter the same way.
Pro Tip: Take a photo of the old filter's size and airflow arrow with your phone. This makes it easy to buy the correct replacement next time.
Check the old filter's condition
Hold the old filter up to a light source. If you cannot see light through it, it was overdue for replacement. A heavily clogged filter means your system has been working harder than necessary, using more energy and wearing down faster.
Insert the new filter
Slide the new filter into the slot with the airflow arrow pointing toward the blower motor (toward the ductwork, away from the return air). The arrow should point in the same direction as the old filter. Make sure the filter fits snugly with no gaps around the edges.
Pro Tip: If the filter is slightly loose, a strip of foam weatherstripping tape around the edges can seal any gaps and prevent unfiltered air from bypassing the filter.
Turn the system back on and note the date
Switch your thermostat back to your normal setting. Write the installation date on the filter frame with a marker so you know exactly when it was last changed. Set a reminder for 90 days to check it again.
Pro Tip: Consider buying 3-4 filters at once so you always have a replacement on hand. Buying in bulk is often cheaper per filter.
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