Which statement is not true about mechanical exhaust discharge?

Which statement is not true about mechanical exhaust discharge?

• A. A back draft damper is required at the point of termination.
• B. Exhaust systems must discharge to the outdoors, unless listed otherwise.
• C. Kitchen or toilet exhaust may terminate in an attic.
• D. Exhaust air must discharge at a point where it will not be readily drawn in by a ventilation system.

Answer: (C)

Mechanical exhaust must be discharged to the outdoors and kept from being drawn back into the building. A backdraft damper is placed at the discharge to prevent outdoor air from sneaking back in when the exhaust fan is off. Exhaust systems are designed to vent to the outdoors, with possible listed exceptions, so the air and any contaminants don’t stay inside the structure. The rule about not allowing exhaust to terminate in an attic is important: attics aren’t proper discharge spaces and aren’t designed to handle moisture, heat, and odors from exhaust; placing kitchen or toilet exhaust there can lead to moisture problems, mold, and potential re-entrainment into the living spaces. Finally, exhaust must discharge where it won’t be readily drawn in by other ventilation paths, ensuring contaminants don’t get pulled back into the building.

Mechanical exhaust must be discharged to the outdoors and kept from being drawn back into the building. A backdraft damper is placed at the discharge to prevent outdoor air from sneaking back in when the exhaust fan is off. Exhaust systems are designed to vent to the outdoors, with possible listed exceptions, so the air and any contaminants don’t stay inside the structure. The rule about not allowing exhaust to terminate in an attic is important: attics aren’t proper discharge spaces and aren’t designed to handle moisture, heat, and odors from exhaust; placing kitchen or toilet exhaust there can lead to moisture problems, mold, and potential re-entrainment into the living spaces. Finally, exhaust must discharge where it won’t be readily drawn in by other ventilation paths, ensuring contaminants don’t get pulled back into the building.