How is the combustion process initiated in a gas furnace?

The combustion process in a gas furnace is initiated through an electronic igniter or pilot light, which serves a critical role in safely lighting the gas that has been released into the combustion chamber. The electronic igniter operates by creating a spark that ignites the gas, ensuring a quick and reliable start to the combustion process. In modern gas furnaces, electronic ignition systems are preferred due to their efficiency and safety in comparison to older pilot light systems or manual ignition methods.

While a thermostat is involved in controlling the overall operation of the furnace by signaling when heating is needed, it does not directly initiate combustion; it simply regulates the system based on the desired temperature. Manual ignition with a match is outdated and not a safe practice due to the risk of gas buildup before ignition. A gas detection system is important for safety to monitor gas leaks, but it does not start the combustion process; it simply provides safety measures to prevent dangerous situations. Thus, the use of an electronic igniter or pilot light is the most effective and modern method to initiate combustion in a gas furnace.