What is the relationship between vent size and draft hood size?

The correct understanding is that vent size must be greater than draft hood size. This is primarily due to the need for proper venting to ensure effective venting of flue gases. A larger vent size compared to the draft hood is crucial to facilitate adequate airflow and maintain a negative pressure, which helps in preventing any backdraft or spillage of combustion gases into the space.

When the vent size is greater than the draft hood, it allows for a more efficient and unobstructed passage for exhaust gases to exit the system. This helps maintain proper operation of appliances and ensures that combustion pollutants are effectively vented outside.

The relationship is influenced by standard codes and practices that dictate these maximum and minimum requirements regarding venting systems, emphasizing the importance of vent size in relation to draft hoods to ensure safety and efficiency in gas appliances.