When a single permanent opening, from the outdoors, is provided for combustion air for other than natural draft equipment, it shall commence within ______ inches from the top of the enclosure.

When a single permanent opening, from the outdoors, is provided for combustion air for other than natural draft equipment, it shall commence within ______ inches from the top of the enclosure.

• A. 9
• B. 3
• C. 12
• D. 6

Answer: (C)

The idea to test here is where an outdoor combustion air opening for equipment that isn’t natural draft should start vertically on the enclosure. For a single permanent outdoor opening supplying combustion air, the top edge of the opening must begin within 12 inches of the top of the enclosure. Placing the intake high on the wall helps ensure a reliable supply of fresh air for the appliance, away from lower-floor disturbances and obstructions, and reduces the chance that window or door leaks, drafts, or nearby furnishings block the opening. Keeping it within 12 inches of the top standardizes placement so the air enters the space efficiently and safely.

The idea to test here is where an outdoor combustion air opening for equipment that isn’t natural draft should start vertically on the enclosure. For a single permanent outdoor opening supplying combustion air, the top edge of the opening must begin within 12 inches of the top of the enclosure.

Placing the intake high on the wall helps ensure a reliable supply of fresh air for the appliance, away from lower-floor disturbances and obstructions, and reduces the chance that window or door leaks, drafts, or nearby furnishings block the opening. Keeping it within 12 inches of the top standardizes placement so the air enters the space efficiently and safely.