Lochinvar & A.O. Smith 100109908 Flame Sensor

The Lochinvar & A.O. Smith 100109908 Flame Sensor is a critical OEM replacement part designed for precise flame rectification in high-efficiency water heaters and boilers. As a seasoned tech, you know that a failing flame sensor rod is the primary culprit behind intermittent data signals and "no flame detected" lockouts. This genuine factory part (formerly identified as part number 9004520215) ensures the flame sensing circuit maintains the microamp signal necessary to keep the gas valve energized. Precise flame monitoring is essential for preventing unburned gas accumulation and ensuring the safety of the combustion cycle. Unlike aftermarket flame sensors, this Lochinvar flame sensor is engineered to meet the exact thermistor and conductivity specifications required by the 100109908 module, providing a reliable flame rectification signal. If you are experiencing rapid cycling or short-flame lockouts, replacing the hot surface ignition system's sensor is the standard procedure to return the unit to peak operational status.

• OEM Compatibility: Specifically engineered for Lochinvar and A.O. Smith units, ensuring seamless integration with the existing ignition control module.
• High-Sensitivity Probe: Features a high-grade flame sensor rod designed to withstand intense combustion temperatures while maintaining signal accuracy.
• Direct Replacement: Replaces deprecated part number 9004520215, making it the current standard for water heater flame sensors in professional applications.
• Reliable Safety: Restores the flame proving sequence, preventing hazardous gas buildup caused by undetected ignition failures.

• Why is my boiler locking out after a few seconds of ignition? A dirty or oxidized flame sensor often fails to send the DC microamp signal to the control board, triggering a safety shutdown.
• Can I clean the 100109908 instead of replacing it? While temporary cleaning with fine-grit steel wool can remove carbon buildup, the porcelain insulator on the OEM flame sensor can develop microscopic cracks that require a full replacement.
• Is this compatible with natural gas and propane units? Yes, this flame rectification sensor is designed to operate within the flame paths of both fuel types in supported models.

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.