How often to change filters will vary based on the type of filter you have. For example, a basic, 1-inch air filter will most likely need to be replaced more often than a larger 4-inch filter. You should follow the filter manufacturer’s recommendations, but a good rule of thumb is to inspect your AC filter at least once every 2-3 months. Additional factors that can affect the timeline of how often you change your filter regularly include:
Thermostat settings: If you tend to enjoy cooler settings in summer, your system will run more often, which may decrease time between filter changes. If you set the thermostat back to save energy, you’ll run the system less and potentially increase time between filter changes.
Poor system installation: An undersized system will run longer and filters will likely collect more pollutants. Poorly installed ductwork may invite more airborne pollutants into the system as well. Both of these examples can potentially reduce the time between filter changes.
Pets: If you are a pet owner, the number, size and type of animals in your home might affect timing between filter changes. Larger animals or longer-haired animals that shed more will shorten the time between filter changes.
Quality/age of home: Older homes or poorly sealed homes tend to draw more dirt, dust and other airborne pollutants from outside. Especially in areas with air pollution issues, you will likely need to inspect and replace your filter more often.
As filter inspections become a part of your routine, you might want to purchase replacement filters in advance and have a clean filter available in case an inspection indicates it’s time for a change.