A safety part for your HVAC system, usually a boiler or furnace, is the Lochinvar 100113151 Flame Sensor Rod Kit. It has a stainless steel rod that is resistant to corrosion and can tolerate temperatures as high as 185°F. The sensor rod is placed inside the burner assembly and uses temperature to determine whether a flame is present. https://www.partshnc.com/flame-sensor-rod-kit-3