The Jandy R0457400 High‑Limit Switch Assembly is a genuine OEM safety component designed for use in Jandy legacy (LRZE/LRZM) and LXi pool and spa heaters. It includes the high-limit temperature sensors and wire harness assembly that monitor outlet water or manifold temperature and initiate shutdown when unsafe conditions are detected. 

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Key Features

• Complete switch harness assembly for high-limit protection in specified Jandy heater models. 

• Compatible with heater families: LRZE-series, LRZM, and LXi Low-NOx units. 

• Triggers at preset temperature thresholds (commonly ~130 °F and ~150 °F) to safeguard against overheating. 

• Plug-and-play harness design for straight-forward installation; maintains manufacturer-spec safety integrity.

• Lightweight, compact component for ease of stocking and service replacement.

• Prevents excessive temperature operation that could damage heat-exchanger, plumbing, or heater components.

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Product Overview
Ensuring safe operation of a gas heater requires reliable temperature monitoring to shut down the system if water or manifold temperatures exceed safe limits. The R0457400 assembly fulfills this by combining high-limit sensors and wiring harness into a ready-to-install OEM kit.
In field service, high-limit trips are a common fault code when flow is restricted, sensors fail, or the manifold overheats. For example, a pool-owner posted: