The cross-sectional area of the common vent must be equal to or greater than what?

The cross-sectional area of the common vent must be equal to or greater than the cross-sectional area of the largest connector. This is critical for ensuring proper venting and preventing backdrafts or inadequate exhaust of combustion gases. A vent with insufficient cross-sectional area can create pressure imbalances that lead to dangerous conditions, such as the accumulation of carbon monoxide and other harmful gases.

Using the largest connector's cross-sectional area as a benchmark ensures that the vent can handle the maximum amount of gas flow from all connected appliances. This is essential for safety and efficiency in gas appliance operation, as it allows for optimal air intake and exhaust pathways.

While other options discuss the area of different connectors, they do not provide the necessary assurance of adequate venting capacity. The focus on the largest connector ensures that even under maximum operating conditions, the vent can safely accommodate the exhaust needs, maintaining a safe and efficient system.