Lochinvar & A.O. Smith 100157743 Kit

Professionals in the field know that maintaining system integrity starts with high-quality safety components. The Lochinvar & A.O. Smith 100157743 Kit is a direct OEM replacement part featuring a 230F manual reset high limit switch. This kit is technically identical to the Lochinvar KIT3117, engineered specifically for high-performance water heaters and boiler systems. When a primary thermostat fails, this 230-degree high limit kit acts as a critical failsafe, opening the control circuit to prevent hazardous overheating conditions. Its manual reset function ensures a technician must physically inspect the unit for underlying issues—such as scaled heat exchangers or restricted flow—before returning the system to service. Built to withstand the thermal cycling typical of commercial hydronic applications, this high limit control provides the precise thermal protection required to keep your clients' equipment running within safe operating parameters. Trust this genuine Lochinvar boiler part for exact fitment and reliable bimetal switch actuation in every service call.

• Exact OEM Compatibility: Serves as a 1:1 replacement for 100157743 and KIT3117, ensuring no mounting modifications are required during install.
• Fixed Thermal Cut-Out: Pre-set at 230°F to provide a rigid safety barrier against excessive water temperatures.
• Manual Safety Reset: Forces a thorough system diagnostic following a high-temperature event, preventing "nuisance" cycling of dangerous conditions.
• Contractor-Grade Durability: Designed for long-term HVAC safety control in both residential and heavy-duty commercial boilers.

What causes this high limit switch to trip frequently?
Repeated tripping typically indicates restricted water flow, excessive lime and scale buildup on the heat exchanger, or a failing primary operating control. Always verify pump operation and temperature rise across the heat exchanger after installing a new 100157743 kit.

Is this part interchangeable with the KIT3117?
Yes. In the Lochinvar and A.O. Smith catalogs, 100157743 is the current part number for what was previously identified as KIT3117. They are functionally and physically identical.

How do I test this switch for proper operation?
With the power off, use a multimeter to check for continuity across the terminals. If the system is cool and there is no continuity, the bimetal disc has likely tripped or the internal contact has failed, necessitating a replacement.

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.