4040 Humidifier Solenoid Valve 24V Water Valve

4040 Humidifier Solenoid Valve 24V Water Valve

Key Features

• Controls water flow for whole-house humidifiers
• Operating Voltage: 24V AC
• Includes in-line strainer, compression sleeve, and nut

Replaces / Cross-Reference Part Numbers

• AprilAire: 4040
• Ranco: 4040-001

Compatibility & Fitment

• Designed for AprilAire Whole-House Humidifiers.
• Compatible Models: 220, 224, 400, 400M, 440, 448, 500, 500M, 550, 550A, 558, 560, 600, 600M, 700

When to Replace

• Humidifier does not receive water when operating.
• Water flow is weak, inconsistent, or stops completely during a cycle.
• Inability to maintain set humidity levels.
• Visible water leaks, drips, or corrosion on the existing valve body.
• Valve makes a buzzing noise but does not open to allow water flow.

Installation Tips

• Before installation, shut off the water supply and disconnect power to the furnace and humidifier.
• Note the water flow direction indicated on the original valve body and install the new valve in the same orientation.
• Use two wrenches during removal and installation to avoid twisting or damaging water lines.
• Ensure the included strainer is correctly seated to prevent debris from clogging the valve.
• After installation, slowly turn the water supply on and check all connections for leaks before restoring power.