The air filter is the cheapest, most-skipped bit of home maintenance. A clogged one strains your furnace and AC and pushes dust right back into your rooms.
How often to swap it
Check monthly; replace most 1-inch filters every 60–90 days. Go shorter if you have pets, allergies, or run the system hard in summer and winter.
Get the size right
The size is printed on the cardboard frame of the old one (like 20x25x1). Match it exactly — a loose filter lets air sneak past unfiltered.
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Do not overpay for MERV
MERV 8–11 handles dust and most allergens for a typical home. Very high MERV can choke airflow on some systems, so higher is not always better.
Set a reminder
Write the date on the new filter’s edge, or set a recurring phone reminder, so it never gets forgotten again.
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