Gas Technician 2 (G2) License Practice Exam 2026 – Your All-in-One Guide to Certification Success!

The correct choice reflects the minimum combustion air requirements for appliances installed in tightly sealed structures without a draft hood. For an appliance with an input of 125,000 BTUH, proper ventilation is critical to ensure adequate air supply for combustion.

In sealed environments, it is necessary to provide enough combustion air to prevent asphyxiation of the combustion process, which can lead to incomplete combustion and the production of harmful gases, such as carbon monoxide. The values established by the National Fuel Gas Code or the relevant local codes dictate the minimum opening size necessary based on the appliance's BTU input. For appliances of this size, the standard requirement is typically 12 square inches of combustion air opening to ensure a safe and efficient combustion process.

The other options do not meet the minimum requirements for safe operation of a combustion appliance. Openings that are too small may lead to insufficient combustion air, thereby causing operational issues and safety hazards. Moreover, zero square inches or too small an opening would not allow for any proper airflow, creating an unsafe situation within the sealed environment.