What is the function of a flame sensor in a gas furnace?

The function of a flame sensor in a gas furnace is to detect flame presence and ensure safety. This component is crucial for the safe operation of the heating system. When gas is introduced into the combustion chamber, the flame sensor monitors whether the furnace is igniting the gas correctly. If the sensor does not detect a flame, it signals the control board to shut off the gas supply, preventing the risk of gas buildup which could lead to dangerous conditions such as explosions or carbon monoxide leaks.

Having a reliable flame sensor is vital for the overall safety of the furnace, as it ensures that heating only occurs if there is a flame burning efficiently and within the combustion chamber. This mechanism helps maintain safe operation by quickly addressing any malfunctions in the ignition process, thus preventing potential hazards.