An outside air inlet for a forced-air heating system must be at least how many feet below a vent located within 10 feet?

An outside air inlet for a forced-air heating system must be at least how many feet below a vent located within 10 feet?

• A. 3, below
• B. 10, above
• C. 2, below
• D. 5, above

Answer: (A)

This tests proper separation between an outdoor air inlet and a nearby exhaust vent to prevent combustion gases from being drawn into the system. The outside air inlet must be placed at least three feet below any vent within a ten-foot horizontal distance to reduce the chance that the exhaust plume is pulled into the intake. This three-foot minimum helps prevent backdraft of combustion products, including carbon monoxide, into the system. If the intake were closer than that or placed above the vent, exhaust could be inducted into the outdoor air stream and into the heating system, creating a safety risk. Therefore, the required spacing is three feet below.

This tests proper separation between an outdoor air inlet and a nearby exhaust vent to prevent combustion gases from being drawn into the system. The outside air inlet must be placed at least three feet below any vent within a ten-foot horizontal distance to reduce the chance that the exhaust plume is pulled into the intake. This three-foot minimum helps prevent backdraft of combustion products, including carbon monoxide, into the system. If the intake were closer than that or placed above the vent, exhaust could be inducted into the outdoor air stream and into the heating system, creating a safety risk. Therefore, the required spacing is three feet below.