Almost all bathroom fans come with a preinstalled backdraft damper in the fan's duct connection. This damper is designed to prevent outside air from coming through the fan's grille when the fan is not running. It does this by only opening when air is flowing in one direction -- from the bathroom to the exterior of the building. If your duct also has a backdraft damper in it, you should remove the one from the fan. The fan may not have enough power to open both dampers, which means no airflow out of your bathroom.
Things You'll Need
Examine the duct outlet of your bathroom fan to find the backdraft damper -- the plastic or metal flapper inside. Inspect the flapper to find the "buttons" on each side that snap into the duct outlet in a premade depression.
Lift up the backdraft damper with a small screwdriver. Grasp the damper firmly.
Twist the damper either direction while pulling straight out. The buttons will release from their depressions and the damper will pull out of the duct outlet.
Tips & Warnings
- If your bathroom fan already is connected to the duct, you must disconnect the duct before you can remove the damper. Remove the screws where it connects to the duct outlet. Once all the screws are removed, pull the duct away from the bathroom fan until it separates from the duct outlet.
- Timothy Gonyo; Sheet Metal Workers Local No. 18; Milwaukee, Wisconsin
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