Replace HVAC filter

Short answer

Every three months, slide out the old filter, check its size, and insert a new one with the airflow arrow pointing toward the furnace.

Priority: High
Difficulty: DIY
Time: 10 min
How often: Every 3 months

Why It Matters

A clogged filter restricts airflow, strains the blower motor, wastes energy, and worsens indoor air quality.

Materials

Replacement filter, same size as the old one

How to Do It

Buy a replacement filter that matches the size printed on the edge of your current filter.
Locate the filter slot, usually on the furnace itself or on the return air duct leading into it.
Slide out the old filter and dispose of it.
Note the airflow arrow printed on the new filter's frame.
Insert the new filter with that arrow pointing toward the furnace (away from the return duct).

Schedule furnace tune-up Once a year
Clean air ducts professionally Every 3 years
Clean HVAC supply vents and registers Every 3 months

Part Of

Last updated 22 September 2026

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