What is the required supply rate for outdoor combustion air provided by a mechanical air supply system?

The required supply rate for outdoor combustion air provided by a mechanical air supply system is determined based on the specific needs of combustion appliances to ensure efficient and safe operation. In the context of this question, option C, which states 0.35 cubic feet per minute, aligns with standard guidelines set for adequate ventilation.

This supply rate is crucial because it helps maintain proper air-to-fuel ratios, preventing issues such as incomplete combustion, which could lead to the production of harmful carbon monoxide and reduced efficiency. Furthermore, this rate considers factors such as the type of appliance, its input rating, and the overall air quality requirements for proper combustion.

The other rates provided do not meet the recommended standards needed to ensure safe and efficient combustion, which emphasizes the importance of selecting the appropriate rate that corresponds to established guidelines in mechanical ventilation practices.