Lochinvar & A.O. Smith 100165923 Flame Sensor

Experienced technicians know that a reliable flame rectification signal is the difference between a high-performance system and a recurring "no-heat" service call. The Lochinvar & A.O. Smith 100165923 Flame Sensor is a critical HVAC replacement part engineered to withstand the intense thermal environment of high-efficiency condensing boilers and commercial water heaters. This OEM component, which is the direct cross-reference for PLT30003 and PLT20002, includes the mounting gasket to ensure a robust, airtight seal at the burner plate, preventing combustion bypass and ensuring accurate microamp readings.

When troubleshooting ignition failure or short-cycling in Lochinvar Crest (FBN/FBL 2500-5000), Copper-Fin, or A.O. Smith Cyclone models, verify the flame rod for carbon fouling or ceramic cracking. The 100165923 provides the precise flame sensing continuity required by the smart valve or control board to maintain the gas valve circuit. Using an internal gasket with this sensor is non-negotiable for maintaining proper cabinet pressure and thermal isolation. This hot water heater sensor is a standard-issue item for professional HVAC maintenance to prevent nuisance lockout codes like A.O. Smith Error 11 or 72.

• Direct OEM Cross: Identical to manufacturer part numbers 100165923 and PLT3003 for seamless field installation.
• Complete Kit: Includes the essential flame sensor gasket to maintain the combustion chamber seal.
• Broad Compatibility: Fits a wide range of Lochinvar boilers and A.O. Smith gas water heaters, including the FB, FBN, and FBL series.
• High Conductivity: Designed for consistent DC microamp signals, ensuring the control board proves flame within the safety timing window.
• Durable Construction: Features a high-grade ceramic insulator and stainless steel rod to resist high-temperature oxidation.

• Why does my system ignite for 4 seconds and then shut down? This is the classic symptom of a dirty flame sensor or a faulty signal. The control board is not receiving the required microamp current through flame rectification and closes the gas valve for safety.
• Can I use this to replace a PLT20002? Yes, the 100165923 is the updated service replacement for the PLT20002 and PLT30003 part numbers.
• Is the gasket required for installation? Absolutely. Replacing the flame sensor gasket ensures there is no air leakage at the mounting point, which can cause combustion issues and improper sensing.

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.