If the pressure switch closes before the induced draft motor starts, what will happen?

In a typical HVAC system, the pressure switch is a safety device that ensures the induced draft motor is functioning correctly before allowing ignition of the furnace. If the pressure switch closes before the induced draft motor starts, it indicates that there is a problem with the proper air flow or venting conditions.

In this case, the Integrated Fan Control (IFC) would not initiate the motor because it relies on the pressure switch to confirm that the system is ready for safe operation. If the switch closes prematurely, it means the system has not reached the required operating conditions, and the IFC will prevent the motor from starting to avoid potential hazards such as the buildup of combustion gases or improper ventilation.

Therefore, the scenario accurately reflects the purpose of the pressure switch as a safeguard, ensuring that the system operates safely and effectively. This understanding of the role of the pressure switch and the subsequent safety protocols in HVAC systems is critical for troubleshooting and operational safety.