Surface Mount Auto-Reset High Limit Switch: Single Pole Single Throw Thermal Fuse Design (NO CAPILLARY)
This thermodisc-style safety switch attaches directly to your heater housing, monitoring actual water temperature as it flows through the heating chamber. The internal bi-metallic disc trips at 121°F, breaking the electrical circuit to prevent overheating. Depending on your control system, this may shut down all spa functions or only disable the heating element while pumps continue operating. Once temperatures drop below the trip point, the disc automatically reforms its original shape, closing the circuit and allowing heater operation to resume. This cycle repeats until the underlying problem is corrected. Unlike manual-reset models, this component requires no physical intervention to restore function.

Testing & Troubleshooting Guide: This is a normally-closed switch, meaning the circuit should be complete during normal operation. Replace this component if any of these conditions exist: circuit remains open at any temperature, switch fails to close when cool, trips before reaching 121°F, or won't automatically reset after cooling below the trip threshold.

Compatible with Sundance Sentry 850 heating systems and Cal Spa heat exchangers featuring wet element design. Cross-reference part numbers include: OEM 314100, 6000-093, SD6000-093, Sundance 6000-093, Allied 2-05-0110. Manufactured by Thermodisc. Also fits Jacuzzi J-200 Series heaters requiring surface-mount high limit protection.