What is the purpose of a flame sensor in a furnace and how does it contribute to the safe and efficient operation of the heating system?

A flame sensor in a furnace detects the presence of a flame. It ensures that the burner is lit and functioning properly. If the sensor does not detect a flame, it shuts off the gas supply to prevent a buildup of gas. This contributes to the safe operation of the heating system by preventing gas leaks and potential hazards. Additionally, the flame sensor helps the furnace operate efficiently by ensuring that fuel is being burned properly, which can save energy and reduce costs.