Ventilation air inlet requirement for category one appliances located between 6\" - 18\" from the floor.

Ventilation air inlet requirement for category one appliances located between 6\" - 18\" from the floor.

• A. located between 6\" - 18\" from the floor
• B. located as close to the ceiling as practical
• C. located mid - point between any two appliances
• D. not required

Answer: (A)

When a category I appliance is installed low in a space, the combustion air inlet must be placed at a similar height to ensure a direct and adequate flow of fresh air into the appliance. The air inlet located between 6 and 18 inches from the floor provides access to air at a level where density and flow are favorable for proper combustion and helps prevent backdrafting or restricted air supply. Placing the inlet higher up or in an unrelated location would pull air from a different part of the room (often warmer and less dense or more stratified) and could compromise safety and performance. Since these appliances rely on a steady supply of outdoor or room air for combustion, the inlet must be within that 6–18 inch band to meet typical code requirements.

When a category I appliance is installed low in a space, the combustion air inlet must be placed at a similar height to ensure a direct and adequate flow of fresh air into the appliance. The air inlet located between 6 and 18 inches from the floor provides access to air at a level where density and flow are favorable for proper combustion and helps prevent backdrafting or restricted air supply. Placing the inlet higher up or in an unrelated location would pull air from a different part of the room (often warmer and less dense or more stratified) and could compromise safety and performance. Since these appliances rely on a steady supply of outdoor or room air for combustion, the inlet must be within that 6–18 inch band to meet typical code requirements.