Lennox 49M84 Flame Sensor

The Lennox 49M84 Flame Sensor is a crucial safety component in Lennox gas-fired HVAC systems. It safeguards against gas leaks by detecting the presence of a flame within the burner assembly. When the furnace ignites, the sensor rod heats up to temperatures between 1200°F and 1800°F. This signals the control board that combustion is happening properly. If the flame sensor doesn't detect a flame or the temperature falls outside the expected range, the control board shuts down the gas supply to prevent a dangerous gas leak. The sensor is a small rod, typically measuring 3 to 5 inches long and 1/16 to 1/8 inches thick.