Kitchen Exhaust Backdraft Damper. If the fan is integrated. Because dryer vent backdraft damper blades are opened by inside air pressure from venting dryers, some applications may require help from a booster exhaust fan.
The duct should be smooth and the range hood duct should have a smooth interior finish, be airtight, and equipped with a backdraft damper (2009 irc m1503).
I'd be interested if there is any work being done on backdraft and downdraft vents, i would guess the capture efficiency would be at the low end but i am always prepared to be surprised by actual data. Also, i have to fit the start collar, backdraft damper, reducer, and two elbows inside of a 24 high cabinet the duct is going. The frame is galvanized steel with aluminum blades. Perfect for your bathroom or kitchen exhaust fan, hydroponics, inline extract fans, or extractor hood.
