Lochinvar & A.O. Smith 100157718 System Sensor

The Lochinvar & A.O. Smith 100157718 System Sensor is a critical OEM boiler replacement part engineered to provide precision water temperature sensing for high-efficiency heating systems. Known in the field as the KIT3078, this sensor is a direct replacement for the discontinued 100274767 and is essential for maintaining the operational integrity of Lochinvar Knight and A.O. Smith commercial and residential units. As a veteran-grade HVAC control sensor, it monitors real-time system parameters to ensure the heat exchanger operates within specified thermal limits, preventing energy waste and thermal stress on the internal components.

This boiler system thermistor is designed for a wired connection directly to the control board, delivering high-accuracy data required for modulating burner firing rates. It is fully compatible with a wide range of models including the KHN, WHN, and KB series (KHN055 through KHN285). By providing exact feedback to the hydronic heating control system, the 100157718 prevents short-cycling and ensures the stability of the heating loop in demanding commercial water heater applications.

• Exact OEM Replacement: Functionally identical to KIT3078 and 100274767 for a seamless drop-in installation without cabinet modifications.
• Enhanced System Efficiency: Delivers precise temperature data to the control unit to optimize fuel consumption and minimize emissions.
• Broad Compatibility: Integrated system sensor for Lochinvar Knight and A.O. Smith units, covering residential and commercial capacities from 55k to 500k BTU.
• Critical Safety Regulation: Monitors for over-temperature conditions to protect the boiler block and prevent localized boiling within the heat exchanger.

Is the 100157718 the same as the KIT3078?
Yes, the 100157718 and KIT3078 are identical parts. Lochinvar and A.O. Smith often cross-reference these numbers for the same temperature sensing kit.

Which boiler models use this system sensor?
This part is the standard Knight boiler system sensor used in WHN, KHN, and KBN models, as well as several A.O. Smith high-efficiency series. Always verify the part number against your specific burner’s technical manual.

What happens if this sensor fails?
A faulty system sensor typically triggers a "Sensor Open" or "Sensor Short" fault code on the digital display, causing the system to lockout to prevent unsafe operation or inaccurate modulation.

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.