How Often Should I Change My AC Filter? A Simple Guide
If you only do one thing for your heating and cooling system, change the air filter. It is cheap, takes a minute, and prevents a long list of problems including poor cooling, frozen coils, high bills, and early equipment failure.
How often to change it
These are general guidelines. Always check the filter monthly and replace it when it looks dirty.
1 inch filters: every 1 to 3 months
4 to 5 inch media filters: every 6 to 12 months
Homes with pets: lean toward the shorter end
Homes with allergies or asthma: change more often
During construction or remodeling: check every couple of weeks
Peak summer and winter: check monthly, since the system runs the most
In Central Oklahoma, wind, dust, pollen, and cottonwood season can load up a filter faster than you might expect.
How to find your filter
Filters are usually located in one of two places: in a slot at the indoor unit (furnace or air handler) or behind a return air grille in a wall or ceiling. Some homes have more than one. The size is printed on the edge of the old filter.
Which filter should I buy?
Filters are rated by MERV, which ranges from 1 to 16 for home filters. Higher numbers catch smaller particles.
MERV 1 to 4: basic fiberglass filters that protect the equipment but do little for air quality
MERV 8 to 11: a great choice for most homes, balancing airflow and filtration
MERV 13: better for allergies, but can restrict airflow on some systems
More is not always better. A very restrictive filter on a system that was not designed for it can reduce airflow and cause the same problems as a dirty filter. If you are unsure, ask us during your next visit.
Install it the right way
Look for the arrow on the edge of the filter. It should point toward the indoor unit, in the direction the air flows.
A simple tip
Write the date on the edge of the filter when you install it, or set a reminder on your phone.
Have questions about filters or indoor air quality? Call Red Rock Mechanical at (405) 305-3085.
Comments