High Limit Switch used in many gas & electric heaters. Used on almost all pool and spa heaters. Found on the Inlet side of a gas pool or spa heater heater.  AKA Thermal Cutout. Commonly fail after time due to corrosion, or when replacing the brass temp sensor locator.

Raypak:
131 Gemini, Raypak 280, Raypak 350, Raypak 430, RP2100 and many more.

Important Information:
- These are an Extremely Important Safety feature found on heaters. They must be replaced when necessary. 
- When installing, make sure both male & female thread are clean. We recommend lightly lubricating the thread, and *gently* screwing them in, as the thread shaft is thin brass. Dirty threads, or over-tightening can break the shaft. This is not covered by warranty.

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