What can prevent a furnace from igniting?

A furnace may fail to ignite for a variety of reasons, and one of the most common causes relates to the components responsible for starting the combustion process. When a furnace has faulty ignitors or dirty burners, it can hinder the ignition sequence.

The ignitor is crucial for providing the necessary spark or heat to ignite the gas, and if it's malfunctioning, the gas will not ignite. Similarly, if the burners are dirty, they may not allow gas to flow properly or may fail to ignite due to blockages or obstructions. This can prevent the furnace from functioning correctly and lead to heating issues in the home. Thus, identifying and addressing these issues with the ignitors and burners is essential for proper furnace operation.

Other factors mentioned, such as clean burners and functioning ignitors, or a good gas supply, ensure that the furnace operates correctly, but if the ignitors are faulty or the burners are dirty, these positive conditions cannot lead to ignition.