Lochinvar & A.O. Smith 100109966 Flame Sensor

The Lochinvar & A.O. Smith 100109966 Flame Sensor is a critical diagnostic component designed for precise flame rectification in high-efficiency commercial boilers and water heaters. This OEM replacement flame sensor (formerly part number 9004526005) ensures the burner control module receives a consistent microamp signal, preventing nuisance lockouts and ignition failure. Constructed with high-grade alumina ceramic insulation and a durable Kanthal sensing rod, it withstands the extreme thermal cycling found in Lochinvar Knight and A.O. Smith Cyclone series units. When troubleshooting a ventilation or combustion error code, verifying the integrity of the 100109966 is a standard diagnostic step. This sensor provides the necessary low-voltage feedback loop to maintain safe burner sequence operation, ensuring the gas valve remains energized only when a stable flame is present. Proper alignment and a clean rod surface are essential for peak signal strength and system reliability.

• Direct OEM Compatibility: Engineered specifically for Lochinvar and A.O. Smith commercial venting systems to eliminate installation variables.
• Enhanced Signal Reliability: Maintains a stable microamp flame signal to the ignition module, reducing service calls for intermittent flame loss.
• High-Temperature Durability: The specialized alloy probe is resistant to carbon buildup and oxidation, extending the intervals between preventative maintenance cleanings.
• Rapid Response Time: Facilitates immediate flame detection during the trial for ignition period, ensuring efficient thermal transfer and safe operation.

How do I test the 100109966 flame sensor?
Set your multimeter to the DC microamp (µA) setting and connect it in series with the flame sensor wire. A healthy reading typically ranges between 2.0 and 6.0 µA, depending on the specific control board requirements.

What causes this flame sensor to fail prematurely?
The most common issues are carbon soot accumulation, cracked ceramic insulators caused by thermal shock, or improper positioning within the burner's flame envelope, which inhibits proper ionization.

Can I clean the rod instead of replacing it?
While light cleaning with a non-abrasive material like steel wool can temporarily restore flame signal, any pitting or degradation of the metal rod warrants immediate replacement to prevent future boiler lockout.

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.