In a mechanical room, the fresh air intake should be located how far from the floor and near which appliance?

In a mechanical room, the fresh air intake should be located how far from the floor and near which appliance?

• A. 12 inches from floor, near the largest BTU appliance
• B. 3 feet from floor, near the smallest appliance
• C. 6 inches from floor, closest to the largest BTU appliance
• D. 6 inches from the floor, far from all major appliances

Answer: (C)

Fresh air for combustion should be delivered where it’s actually needed most: to the appliance with the largest fuel input. Placing the fresh air intake closest to that largest BTU appliance ensures that this demand gets met first, helping prevent the appliance from being starved for air and reducing the risk of backdrafting or incomplete combustion when other devices in the room are also using air. Positioning the intake about 6 inches from the floor keeps the opening low enough to draw in denser outdoor air and minimizes interference from warm room air or obstructions near the ceiling. It also aligns with common practice in mechanical rooms where the most critical supply is routed directly to the appliance that consumes the most air. If the intake were placed higher up or farther from the largest appliance, the largest burner could experience air shortfalls, leading to performance issues or safety concerns. So, the best choice is to locate the fresh air intake 6 inches from the floor, as close as possible to the largest BTU appliance.

Fresh air for combustion should be delivered where it’s actually needed most: to the appliance with the largest fuel input. Placing the fresh air intake closest to that largest BTU appliance ensures that this demand gets met first, helping prevent the appliance from being starved for air and reducing the risk of backdrafting or incomplete combustion when other devices in the room are also using air.

Positioning the intake about 6 inches from the floor keeps the opening low enough to draw in denser outdoor air and minimizes interference from warm room air or obstructions near the ceiling. It also aligns with common practice in mechanical rooms where the most critical supply is routed directly to the appliance that consumes the most air. If the intake were placed higher up or farther from the largest appliance, the largest burner could experience air shortfalls, leading to performance issues or safety concerns.

So, the best choice is to locate the fresh air intake 6 inches from the floor, as close as possible to the largest BTU appliance.