Lochinvar & A.O. Smith 100109888 Gas Valve

The Lochinvar & A.O. Smith 100109888 Gas Valve is an OEM natural gas control valve engineered for precision combustion in high-efficiency boilers and water heaters. Designed for 24V applications, this negative pressure gas valve facilitates the exact air-to-fuel ratio required for modern condensing units. For technicians troubleshooting a "GV Relay Fail" or ignition lockout, this valve serves as the direct replacement to restore reliable burner operation. The robust internal solenoid construction ensures consistent gas flow regulation under varying inlet pressures, maintaining the 3.5" WC standard common in many Lochinvar Knight and A.O. Smith ProLine XE series. When performing a swap, always verify the gas valve manifold connection and inspect the venturi flange for debris or moisture, which often indicates heat exchanger backflow issues. This gas water heater control valve is built to withstand high-cycle commercial and residential environments, providing the safety and modulation necessary for peak thermal efficiency and low-NOx performance.

• OEM Compatibility: Precision-matched for Lochinvar and A.O. Smith heating systems to ensure seamless gas valve installation.
• Enhanced Safety: Integrated redundant solenoid valves prevent hazardous gas leakage and ensure immediate shutdown during flame failure.
• Optimal Combustion: Supports negative pressure regulation for precise modulation and improved fuel economy.
• Durable Construction: Engineered to hold steady pressure at 3.5" water column, reducing erratic burner behavior.

How do I diagnose a faulty 100109888 valve?
If the control board signals a "GV Relay Fail" or the unit fails to ignite despite a spark, check the 24V signal at the Molex connector. Use a manometer to verify if the valve opens and the manifold pressure rises from negative toward zero during the ignition trial.

Can this natural gas valve be converted to LP?
This specific model is calibrated for NAT GAS. Any conversion to liquid propane requires a manufacturer-approved LP conversion kit with the correct orifice and spring adjustments; never attempt a field conversion without the designated OEM kit.

Why is my boiler locking out with a "Gas Valve Fault"?
This often occurs due to a bad wiring harness, moisture in the electrical terminals, or a failed internal coil. Ensure the 24V power supply is stable and that there is no water backup in the valve outlet from a restricted heat exchanger.

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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.