Where does dilution air enter the chimney?

Where does dilution air enter the chimney?

• A. Through the air inlet at the appliance
• B. The draft hood
• C. At the chimney crown
• D. Through the exhaust vent

Answer: (B)

Dilution air enters the chimney through the draft hood. The draft hood is a chamber attached to the appliance outlet that allows room air to enter the vent as combustion gases rise, diluting the flue gases and helping to maintain a balanced, stable draft. This entry point is specifically designed to supply the dilution air needed for proper venting and to prevent backdrafting when wind or cycling changes occur. Other points like the appliance’s air inlet are for combustion air, while the chimney crown and exhaust vent are part of the exhaust path, not entry for dilution air.

Dilution air enters the chimney through the draft hood. The draft hood is a chamber attached to the appliance outlet that allows room air to enter the vent as combustion gases rise, diluting the flue gases and helping to maintain a balanced, stable draft. This entry point is specifically designed to supply the dilution air needed for proper venting and to prevent backdrafting when wind or cycling changes occur. Other points like the appliance’s air inlet are for combustion air, while the chimney crown and exhaust vent are part of the exhaust path, not entry for dilution air.