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The Mr. Heater 21925 Thermocouple is a genuine OEM replacement part designed to restore proper flame-sensing operation in Mr. Heater and Heat Star infrared heaters. This 13-inch thermocouple is built to original factory specifications and ensures safe, reliable heater performance.
This part fits Mr. Heater MH125 and Heat Star HS125 LP/NG units not equipped with a tip or limit switch, typically manufactured between 2009–2013. If your heater fails to stay lit or shuts down shortly after ignition, a worn or damaged thermocouple is often the cause.
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