If the Vent Motor fails, which component will shut off the Gas Valve and stop the Gas Flow?

The air pressure switch is designed to monitor the airflow within the venting system of a gas appliance. If the vent motor fails and airflow is disrupted, the air pressure switch will detect the lack of sufficient pressure, indicating that the venting system is not functioning correctly. In such an event, the air pressure switch will open its circuit, effectively shutting off the gas valve to prevent gas from flowing into the burner system. This safety feature is crucial to avoid potential hazards, such as gas buildup, which could lead to dangerous situations, including explosions or poisoning.

The other components, while important in the overall operation of a gas appliance, do not directly monitor or respond to the vent motor's performance in the same way. The gas regulator manages gas pressure, the power switch controls the appliance's overall electrical supply, and the thermostat regulates the temperature, but they do not have the capability to shut off the gas valve in response to a vent motor failure. Thus, the air pressure switch plays a critical role in ensuring the safe operation of gas appliances by responding to changes in venting conditions.