There are several different types of air filters and their replacement intervals vary.  In addition, your lifestyle can determine how often air filters are changed.  The disposable filters in your returns should be replaced every 30 days.  The pleated filters can be replaced every 90 days.  Large media filters and CleanEffect filters are replaced about once per year.  If you have pets, smoke or have some other issue where allergens can get in the air, you will need to replace your filters more often.  Learn more about air filters by reading our article on benefits of changing your air filter.