What is draft air primarily mixed with in a draft hood?

Draft air in a draft hood is primarily mixed with flue gases to ensure proper ventilation and safe discharge of combustion byproducts. The draft hood is designed to enhance combustion efficiency by providing a controlled situation whereby fresh air can mix with the escaping flue gases from appliances such as water heaters or furnaces.

This mixing is vital as it helps to reduce the concentration of pollutants and ensures that flue gases are adequately diluted before they are expelled into the atmosphere. The draft hood serves an important safety role by preventing the backdraft of flue gases into living spaces while allowing the appliance to function correctly.

The other options do not accurately reflect the purpose or function of the draft air in this context. Ambient air refers to the surrounding air, polluted air does not specify a connection to the operational needs of combustion equipment, and exhaust air typically refers to air expelled from a system without context to mixing with flue gases—all of which do not align with the primary function of draft air in a draft hood.