Change HVAC filter

Replace your HVAC air filter to maintain air quality and system efficiency

Why it matters#

A dirty filter makes your system work harder, increasing energy bills by 5-15% and reducing equipment lifespan. It also circulates dust, allergens, and particles through your home.

What you'll need#

Materials#

Replacement air filter (check size on current filter, e.g., 16x25x1)

Check these common locations: inside the return air vent (large vent on wall or ceiling), in a slot on the side/bottom of the air handler, or in a filter grille where ductwork connects to the furnace/air handler.

2. Turn off your HVAC system#

Optional but recommended. This prevents unfiltered air from being pulled through while you work and makes it easier to handle the filter.

3. Remove the old filter#

Open the vent cover or access panel and slide the filter out. Note the airflow direction arrow printed on the frame—you'll need to match this with the new filter.

4. Check the filter size#

Read the size printed on the filter edge (e.g., 16x25x1, 20x20x4). If not visible, measure length x width x depth in inches. Write this down or take a photo for future reference.

5. Insert the new filter#

Align the new filter with the airflow arrow pointing toward the blower/furnace (toward the unit, away from the living space). The arrow should point in the direction air flows through the system.

6. Mark your calendar#

Write today's date on the filter edge with a marker. Set a reminder for 1-3 months depending on your filter type, household (pets, allergies), and home conditions.

Pro tips#

Buy filters in bulk to save money and always have one ready
Homes with pets or allergies may need changes every 1-2 months
Pleated filters last longer than fiberglass but cost more—they're usually worth it
MERV 8-11 is ideal for most homes; higher ratings can restrict airflow in older systems
If your filter is black/gray after just 2 weeks, investigate—you may have an air quality issue

Warnings#

Never run your HVAC without a filter—debris will damage the system
Make sure the filter fits snugly with no gaps around the edges
Don't use a higher MERV rating than your system is designed for—check your manual

When to call a pro#

If you can't locate your filter, the filter housing is damaged, or you notice unusual noises, smells, or poor airflow even with a clean filter.