The Air Filter Alertâ„¢ monitor reminds homeowners to replace or clean furnace air filters. According to the manufacturer, the device easily attaches to a return air vent. Then an electronic tone sounds either after a programmed number of months have passed or the filter gets dirty, whichever comes first. A filter is determined to be dirty when it is detected to have a 20 percent reduction in airflow from the time the detector was last reset. Two AA batteries are included.
Air Filter Alert Inc., 24992 Normans Way, Calabasas, CA 91302; 818-225-5313; 818-225-5314 (fax); www.airfilteralert.com.