A venting system that removes vent gases under non-positive static pressure is also known as a _____.

A venting system that removes vent gases under non-positive static pressure is also known as a _____.

• A. Conventional vent system
• B. Natural draft system
• C. Direct vent system
• D. Power vent system

Answer: (B)

Natural draft venting relies on the buoyancy of hot combustion gases. Because the gases are heated, they rise up the vent and out of the building without any mechanical help, creating flow driven by the stack effect and resulting in non-positive static pressure in the vent. This makes it the best description for a system that removes vent gases without a fan or other forced-draft device. A power-vent system uses a blower and creates positive pressure to push the gases out, while a direct vent system uses sealed, outside-air intake and exhaust with different pressure characteristics. The term conventional vent is less specific, but natural draft clearly matches the described mechanism.

Natural draft venting relies on the buoyancy of hot combustion gases. Because the gases are heated, they rise up the vent and out of the building without any mechanical help, creating flow driven by the stack effect and resulting in non-positive static pressure in the vent. This makes it the best description for a system that removes vent gases without a fan or other forced-draft device. A power-vent system uses a blower and creates positive pressure to push the gases out, while a direct vent system uses sealed, outside-air intake and exhaust with different pressure characteristics. The term conventional vent is less specific, but natural draft clearly matches the described mechanism.