For optimal performance change your furnace filter at least every 90 days.
Use a 3-month pleated 1-inch home HVAC filter in your furnace air conditioner or HVAC system.Pleated Air Filter, MERV 5, 14 in W x 20 in H x 1 in D Made with exclusive Filtrete 3-in-1 technology including an MPR 300 and MERV 5 rating your AC filter will help pull and capture lint household dust and dust mite debris while letting cleaner air flow through.. Filtrete 14x20x1 MPR 300 Air Filter made by 3M helps capture unwanted particles from your household air to contribute to a cleaner fresher home environment.