Lochinvar & A.O. Smith 100170574 Limit Switch

The Lochinvar & A.O. Smith 100170574 is a critical safety component designed for high-limit temperature monitoring in commercial and residential heating systems. Operating within a precise range of 50-270°F, this manual reset limit switch (M/R) functions as a fail-safe to prevent heat exchanger damage and unsafe operating conditions. Also identified as the TST2015, this switch ensures that if temperatures exceed the calibrated threshold, the burner circuit is interrupted and requires a manual technician intervention to restart the system, facilitating a necessary safety inspection. This OEM replacement part is engineered for high-accuracy thermal response and is compatible with a wide array of Lochinvar boilers and A.O. Smith water heaters. Integrating this genuine limit control maintains the intended sequence of operation and protects the structural integrity of the appliance under high-demand HVACR applications.

• Precise Thermal Protection: Monitors internal temperatures from 50°F to 270°F to protect against overheating.
• Manual Reset Security: The M/R functionality ensures the unit stays offline until a technician confirms the system is safe to operate.
• Exact OEM Specifications: Direct replacement for part 100170574 and TST2015, ensuring seamless fitment and electrical compatibility.
• System Longevity: Prevents permanent damage to heat exchangers and internal components by cutting power before reaching critical failure points.

Is this switch compatible with my specific boiler model?
The 100170574 is used extensively across Lochinvar and A.O. Smith platforms. Because these parts are model-specific, you should verify the part number in your equipment’s technical manual or contact a specialist to confirm the serial number compatibility.

What is the difference between an auto-reset and a manual reset limit switch?
An auto-reset switch closes the circuit once it cools down, whereas a manual reset limit switch like this one requires a physical press of the reset button. This is a safety requirement for high-limit scenarios to ensure the cause of the overheat is investigated.

Can I use a generic limit switch as a substitute?
Using non-OEM components in a water heater safety circuit can lead to improper calibration and potential safety risks. Always use factory-authorized parts to maintain professional HVACR standards and equipment reliability.

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.