The Lochinvar 100187882 Flame Sensor is a crucial safety component in gas-fired HVAC equipment like furnaces and boilers. Made of ceramic and measuring 3-4 inches long, it withstands high temperatures (up to 1000°C) while operating on a low voltage range (5-30V). This sensor detects the presence of a flame by sensing the ultraviolet light it emits. It then transmits this signal to the... https://www.partshnc.com/flame-sensor-121