What component prevents operation when the vent motor on a power vent water heater fails?

The pressure switch plays a critical role in ensuring the safe operation of a power vent water heater. When the vent motor fails, the pressure switch detects this malfunction and prevents further operation of the appliance. This is an essential safety feature designed to avoid dangerous situations that might arise from inadequate venting, which could lead to the accumulation of harmful combustion gases inside the home.

The pressure switch functions by monitoring the airflow generated by the vent motor. If the motor ceases to operate, airflow is disrupted, triggering the pressure switch. This switch then signals the gas valve to shut off, ensuring that combustion does not occur without proper venting, thus protecting both the appliance and the occupants of the home from potential hazards.

In this context, the other components listed do not have the same primary safety function linked specifically to the failure of the vent motor. For example, while the thermostat controls the temperature of the water, it does not directly respond to the status of the vent motor. Similarly, the gas valve and limit switch have different operational controls in the system, focusing on gas supply management and temperature regulation, respectively. Thus, the pressure switch is uniquely responsible for safety during a vent motor failure.