AprilAire #4640 Humidifier Scale Control Insert, Replacement Part
AprilAire 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
