Which option best describes the function of a draft hood on an atmospheric furnace?

Which option best describes the function of a draft hood on an atmospheric furnace?

• A. To regulate flame
• B. To neutralize negative pressure in the structure
• C. To filter exhaust gases
• D. To provide secondary air for combustion

Answer: (B)

Balancing pressure in the venting system of an atmospheric furnace to prevent backdraft is what the draft hood is all about. It provides a controlled opening that allows pressure differences between the building and the vent to equalize, so flue gases can exit the chimney without being pushed back into the living space. When the house is under negative pressure or wind creates pressure changes, the draft hood helps keep the flue gases flowing upward rather than pulling air from the room back down the vent. It isn’t used to regulate the burner flame, isn’t a filter for exhaust gases, and isn’t intended to supply secondary air for combustion—the furnace’s flame control governs the flame, filtration isn’t the draft hood’s job, and combustion air typically comes from the room or outdoors through a separate path.

Balancing pressure in the venting system of an atmospheric furnace to prevent backdraft is what the draft hood is all about. It provides a controlled opening that allows pressure differences between the building and the vent to equalize, so flue gases can exit the chimney without being pushed back into the living space. When the house is under negative pressure or wind creates pressure changes, the draft hood helps keep the flue gases flowing upward rather than pulling air from the room back down the vent.

It isn’t used to regulate the burner flame, isn’t a filter for exhaust gases, and isn’t intended to supply secondary air for combustion—the furnace’s flame control governs the flame, filtration isn’t the draft hood’s job, and combustion air typically comes from the room or outdoors through a separate path.