What is the function of the limit switch in a gas furnace?

The limit switch in a gas furnace is primarily designed to prevent overheating by monitoring the temperature within the furnace. When the temperature reaches a predetermined threshold, the limit switch will shut off the burner to prevent damage to the furnace and reduce the risk of fire. This safety mechanism ensures that the furnace operates within safe temperature limits, protecting both the equipment and the home.

In the context of a gas furnace, safety is paramount, and the limit switch plays a crucial role in maintaining safe operation. It does not ignite the burner, control gas flow, or monitor indoor air quality, which are functions fulfilled by other components in the furnace system. The effective operation of the limit switch is essential for preventing dangerous situations and ensuring efficient heating.