AprilAire #4640 Humidifier Scale Control Insert, Replacement Part SSX140301B Renovations in the home that

Renovations in the home that create wood or drywall dust or similar contaminants will shorten the life expectancy of the HEPA filter

factory recommended upgrade kit

All 500 and 600 Models: 550

Replacement True HEPA Filter # W4-0840

Carrier or Bryant Filter Model #   PGAPAXX1625

AprilAire #4640 Humidifier Scale Control Insert, Replacement Part SSX140301B Renovations in the home thatAprilAire Humidifier Scale Control Insert Replacement Part # 4640 This is the u shaped component which encases the Water Panel Evaporator. Used with water panel number 10 and the water distribution tray number #4331 , sold separately Fits: Aprilaire Model 500, 500A and 500M