Apprentice question
Verify first
Verify before you commit. Cheap to catch now.
Backdraft dampers are directional. If the fan closes the blades instead of opening them, pull and reinstall the damper in the correct airflow direction.
['A backdraft damper is supposed to open with fan flow and close when the fan shuts off. If it is reversed in a louver sleeve, the fan can press the blades shut and make the system look blocked.', 'Check the airflow arrow, blade swing, and fan direction. Remove the damper frame, flip it to the correct direction, and test that the blades swing freely before reconnecting the duct or sealing the sleeve.']