Lochinvar & A.O. Smith 100291049 Sensor Assembly

The Lochinvar & A.O. Smith 100291049 Sensor Assembly is a critical NTC component designed for high-precision thermal monitoring in commercial and residential water heating systems. This SA-10K thermistor kit provides essential feedback to the control board by translating fluid temperature into electrical resistance (10K ohms at 77°F/25°C). Engineered specifically for 2-4 channel systems, this assembly allows for accurate multi-point data collection, ensuring that boilers and water heaters maintain setpoint temperatures without excessive cycling or overheating.

As a genuine OEM replacement, it is built to the exact electrical and physical tolerances required by A.O. Smith and Lochinvar digital control circuits. The 100291049 temperature sensor is frequently utilized in diagnostic sequences to resolve error codes related to sensor failure or "out of range" resistance readings. Replacing a drifting or faulty thermistor with this factory-spec assembly restores thermal efficiency and helps prevent the unsafe operation of high-recovery units. This component is optimized for performance in harsh HVACR environments, meeting rigorous standards for chemical and heat resistance.

• System Compatibility: Explicitly engineered for 2-channel to 4-channel control setups in Lochinvar and A.O. Smith boilers.
• High-Accuracy Monitoring: Features an SA-10K NTC thermistor element for stable, non-linear resistance output across various operating ranges.
• OEM Reliability: Direct factory match for part number 100291049, ensuring correct plug-and-play integration with the main control board.
• Operational Safety: Provides the precise thermal feedback necessary to avoid scalding risks and equipment damage from overheating.
• Direct Troubleshooting Solution: Resolves common sensor-related fault codes (e.g., E20, E21) in compatible water heating equipment.

How do I test if my existing 100291049 sensor is faulty?
Using a digital multimeter set to ohms, disconnect the sensor and measure resistance. At room temperature (approximately 77°F), the reading should be near 10,000 ohms. A reading of infinity (open) or zero (short) indicates a failed sensor.

Is this sensor compatible with both tank-type and tankless units?
This assembly is used across a variety of Lochinvar and A.O. Smith products, including select commercial gas and electric units. Always verify your specific model and serial number against the manufacturer’s parts list to confirm the 100291049 is the correct part.

Can I use a universal 10K sensor instead?
While many thermistors are rated at 10K, the resistance curve and wire harness configuration of the 100291049 are specific to Lochinvar and A.O. Smith control logic. Using a non-OEM part may lead to inaccurate temperature readings or system errors.

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.