Weil McLain 511-624-401 Pressure Switch

The Weil McLain 511-624-401 Pressure Switch is a critical safety component designed specifically for high-efficiency gas boilers, including the Weil-McLain CGi-25 and CGi-3 series. As an OEM air pressure switch, it is factory-calibrated to a precise 1.79" WC (water column) set point to monitor the pressure differential created by the inducer blower. This SPST (Single Pole Single Throw) switch remains normally open and closes only when the system achieves the necessary venting pressure, ensuring safe combustion air flow before ignition. Featuring dual 1/4" barb connections, this switch provides a secure fit for silicone sensing lines to prevent vacuum leaks that cause nuisance short cycling or lockout codes.

For technicians servicing residential gas boilers, replacing a failed switch with this genuine Weil-McLain replacement part ensures the unit maintains its original safety parameters. This differential pressure switch is built for the rugged environment of a boiler cabinet and is rated for altitudes from 0' to 1999'. Proper installation of the 511-624-401 restores the sequence of operation and protects against dangerous blocked vent conditions.

• Precise Calibration: Factory set at 1.79" WC for reliable monitoring of the inducer motor performance.
• Direct OEM Fit: Guaranteed compatibility with Weil-McLain CGi series boilers, avoiding the drift issues common in universal components.
• Enhanced Connectivity: Features dual 1/4" barb connections for positive and negative pressure sensing lines.
• Safety Logic: The SPST configuration ensures the burner cannot fire if flue gas venting is obstructed.

• What causes a Weil-McLain 1.79" WC pressure switch to fail? Failures are often caused by diaphragm wear, moisture accumulation in the sensing lines, or dust blocking the 1/4" barb ports.
• How do I test the 511-624-401 for proper operation? Use a manometer to verify the inducer is pulling at least 1.79" WC and check for continuity across the SPST terminals when the vacuum is applied.
• Is this switch compatible with high-altitude kits? This specific model is rated for 0' to 1999'; high-altitude applications require a different Weil-McLain pressure switch with a lower set point.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.