| Genuine Aprilaire 4640 Scale Control Insert for Model 500 |
 The Aprilaire Scale Control Insert 4640 is the U-shaped component which encases the Water Panel Evaporator. Used with water panel number 10 and water distribution tray part number 4331. For Models 500A and 500M. Supplemental Information: Aprilaire 500 Series Installation Guide Aprilaire Humidifier Owner's Manual Related Products: Aprilaire 4330 Scale Control Insert For Model 600 Aprilaire 4040 24 Volt Solenoid Valve Aprilaire 4793 Humidifier Maintenance Kit Price: 19.99 |