CSIA Certified Dryer Exhaust Technician (C-DET) Practice Exam

Draft is the movement of air and exhaust gases in a vent. When that flow is driven by buoyancy from a temperature difference, it’s natural draft. If an external device like a fan, blower, or jet pushes or pulls the air, that flow is mechanical draft. A draft produced by a fan or air/steam jet is mechanical draft because the airflow is being created by an outside force rather than by the natural rise of hot gases. In dryer exhaust systems, mechanical draft can improve venting in longer or more complex runs and help prevent back-drafting. The other terms don’t describe how the flow is created: natural draft relies on buoyancy, NFPA 211 is a standard for chimneys and venting but not a draft type, and NCSG isn’t a recognized term for draft classification.