What is the minimum size opening for outdoor combustion air intakes?

The minimum size opening for outdoor combustion air intakes is 3 inches. This specification is critical for ensuring that combustion appliances receive an adequate supply of air for efficient operation while also maintaining safe operating conditions. Proper sizing of air intakes helps prevent potential issues such as backdrafting or incomplete combustion, which can lead to the production of harmful gases like carbon monoxide.

In the context of appliance installation and ventilation practices, the 3-inch minimum size is designed to promote sufficient airflow while minimizing the risk of blockage or restriction that may occur with smaller openings. This size balances performance needs with installation feasibility and safety standards, making it essential for compliance with regulations governing safe gas appliance operation.