What is the required combustion air opening size for appliances in a structure with an equivalent leakage area greater than 0.05 square meters, given specific input BTUs?

The required combustion air opening size for appliances is determined by the guidelines set forth by safety codes, which take into account factors such as the volume of air needed for combustion and the specific BTU input of the appliance. In this context, an equivalent leakage area greater than 0.05 square meters suggests that the structure has significant air leakage, allowing for some natural ventilation.

A combustion air opening of 9 square inches is appropriate for appliances operating in such conditions, as it balances the need for adequate air supply with the potential effects of uncontrolled air movement related to leakage. This size ensures that there is enough air available for safe combustion without risking excessive draft or air loss that could complicate appliance performance.

Other sizes might not provide the optimal amount of air needed for proper combustion or might exceed what is necessary, leading to inefficiencies or operational issues. Therefore, 9 square inches is specifically chosen to meet safety standards and operational efficiency based on these conditions.