Lochinvar & A.O. Smith 100108951 Thermostat

The Lochinvar & A.O. Smith 100108951 Thermostat is a critical OEM replacement part designed for high-performance commercial and residential electric water heaters. As a heavy-duty upper thermostat, it provides precise temperature control to ensure the heating elements cycle correctly and maintain system efficiency. This thermal regulator comes integrated with an Emergency Cut Off (ECO) safety switch, which manually trips to prevent overheating conditions that could lead to tank damage or component failure. The 100108951 model is engineered specifically for Lochinvar and A.O. Smith water heaters, ensuring a direct fit and electrical compatibility with the original wiring harness. The package includes the necessary protective thermostat cover to shield sensitive electrical contacts from moisture and debris, common in demanding mechanical room environments. For contractors handling water heater repair, using this genuine 100108951 upper thermostat with ECO is essential for restoring the safety and reliability of the appliance's thermal management system.

• OEM Precision: Genuine Lochinvar 100108951 part ensures the temperature sensing calibration matches the original factory specifications for consistent performance.
• Integrated ECO Safety: Features a manual-reset Energy Cut Off to provide secondary protection against high-limit temperature excursions.
• Durable Construction: Built with high-temperature resistant materials and includes a protective thermostat cover for long-term reliability in humid conditions.
• Technician Friendly: Standardized terminal layout and included mounting hardware facilitate a seamless swap during routine HVACR maintenance.

How do I know if the ECO has tripped on my 100108951 thermostat?
If your water heater has no power despite the breaker being on, check the red reset button on the upper thermostat. A visible or "clicked out" button indicates a high-limit trip. Resetting it may restore power, but persistent tripping usually indicates a faulty element or scale buildup.

Is this part compatible with non-Lochinvar brands?
While A.O. Smith manufactures parts for several brands, this 100108951 thermostat should only be used in systems where the technical manual specifically lists this part number to ensure correct amperage and voltage ratings.

What is the difference between an upper and lower thermostat?
The upper thermostat (like the 100108951) manages the initial heating cycle and controls the ECO safety switch. It prioritizes heating the top of the tank first before passing power to the lower element via the lower thermostat.

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.