Honeywell Thermocouple Q370A 1006

This thermocouple is a flame detection device for atmospheric gas burners. It generates a small millivolt signal when heated by a pilot burner flame, which holds open a safety gas valve. The cable length is 900 mm. The maximum operating temperature is 750 °C at the hot junction and 415 °C at the cold junction.

Replacements of this type are selected by thread type, tip style, and cable length; these must match the existing pilot burner and gas valve layout. The tip must seat correctly in the pilot burner bracket, and the retaining nut should tighten without cross-threading. Measure the distance from the pilot burner to the gas valve to confirm the cable reaches.

These thermocouples commonly fail from a broken sheath or diminished signal output caused by thermal cycling or tip contamination. The equipment may keep the pilot lit but fail to fire the main burner, or the pilot may go out after the reset button is released. Checking the tip for contamination and the sheath for damage can reveal the fault.