Which component provides a positive induced draft in a vented appliance system?

Which component provides a positive induced draft in a vented appliance system?

• A. Draft hood
• B. Regulator vent
• C. Mechanical exhaust system
• D. Orifice

Answer: (C)

Induced draft is created when a device actively pulls combustion products through the vent and up to the outdoors. A positive induced draft means a fan or blower is producing that upward flow, ensuring the flue gases are drawn out of the appliance system rather than spilling into the room. The mechanical exhaust system provides this by housing an induced-draft fan that pulls the gases through the vent, creating the necessary draft. The other components don’t generate the draft: a draft hood is a passive device that helps regulate venting and prevent backflow, not a motor to move the gases. A regulator vent serves to vent gas from the regulator, not to move combustion products through the vent. An orifice controls the burner’s gas flow, with no role in draft generation.

Induced draft is created when a device actively pulls combustion products through the vent and up to the outdoors. A positive induced draft means a fan or blower is producing that upward flow, ensuring the flue gases are drawn out of the appliance system rather than spilling into the room. The mechanical exhaust system provides this by housing an induced-draft fan that pulls the gases through the vent, creating the necessary draft.

The other components don’t generate the draft: a draft hood is a passive device that helps regulate venting and prevent backflow, not a motor to move the gases. A regulator vent serves to vent gas from the regulator, not to move combustion products through the vent. An orifice controls the burner’s gas flow, with no role in draft generation.