In a gas furnace equipped with an induced draft motor, which switch must function properly to continue the ignition sequence?

In a gas furnace equipped with an induced draft motor, the pressure switch plays a crucial role in ensuring safe and efficient operation. This switch detects whether the induced draft motor is generating sufficient airflow through the flue for proper venting of combustion gases.

Before the ignition sequence can proceed, the pressure switch must close, indicating that there is adequate draft and that the system is safe to operate. If the pressure switch does not function correctly or fails to close, the ignition process will be inhibited to prevent the risk of gas build-up or unsafe operating conditions.

The importance of the pressure switch in this context is underscored by its role in safeguarding the system, as it prevents ignition if there is insufficient airflow, which could indicate a blockage or malfunction in the venting system. This ensures that the furnace operates safely and efficiently, aligning with safety protocols and reducing the risk of hazardous situations.