The Raypak 006021F Roll-Out/Flue Sensor 150°F is a safety control device designed to monitor excessive heat around the burner and flue areas of compatible gas-fired HVAC equipment. Calibrated to activate at 150°F, it detects abnormal temperature conditions caused by blocked vents or flame roll-out and interrupts the burner circuit to help prevent unsafe operation. Commonly used in Ray... https://www.partshnc.com/006021f-raypak-roll-outflue-sensor-150f