Industrial Maintenance Technician Practice Test

A limit switch is a critical safety device found on a gas-fired furnace. It plays a vital role in the safe operation of the furnace by monitoring the temperature within the system. When the temperature exceeds a predetermined limit, the limit switch opens the circuit, which can shut off the gas supply or discontinue the furnace operation. This prevents overheating and potential hazards such as fire or equipment damage.

In the context of furnace operation, the limit switch is essential for ensuring that the furnace operates within safe temperature ranges, providing both safety for the equipment and protection for the occupants of the building. While a thermostat is responsible for regulating the temperature by turning the furnace on or off, and a pressure relief valve is aimed at preventing excessive pressure in gas systems, the limit switch specifically addresses temperature regulation in a safety capacity. A humidistat, on the other hand, is used to control humidity levels rather than directly contributing to the safety of the gas furnace operation.