What is the minimum sized combustion air opening for a confined space connected to an unconfined space?

In a confined space that is connected to an unconfined space, the minimum size of the combustion air openings must comply with safety standards to ensure there is adequate air for proper combustion of cooking appliances. The correct answer of 100 square inches reflects the established guidelines which state that for each 1,000 BTUs of input rating of the appliance, at least 1 square inch of combustion air opening is required.

When appliances are used in a confined area that also has a source of combustion air from an unconfined space, the total calculated input should lead to having sufficient airflow that meets operational and safety needs. Ventilation is crucial to prevent the buildup of harmful gases and to ensure efficient operation. This is why 100 square inches is deemed appropriate, as it provides the necessary airflow for effective combustion and minimizes risks associated with inadequate combustion air.

Other larger options, while they may appear to offer increased safety, exceed the minimum requirements set forth by regulations, thus being unnecessary for the scenario described.