AirFlo 20 inch Gravity Backdraft Damper Shutter

National Fan Co.
Build Time:
7 to 10 Business Days ?
Ships By:
FedEx Ground

Build Time

The product Build Time you see represented on this site is only a typical number of days the manufacturer states it needs to build the product(s) when ordered. Build times are based on business days (excludes weekends & holidays).

The build time does not include the time it will take to ship the order to you (the customer). If an order has multiple items and comes from multiple warehouses, you may receive part of your order on one day, and then receive the remaining part(s) of your order at a later date.

*Please be aware that seasonal demand of certain equipment may cause build times to run longer than what is typical.

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LIST: $170.95
Only $123.57
Quantity Unit Price You Save
6-9 3%
10+ 5%

Inside Mount Series 3200M - alum.

Outside Mount Series 3100M - alum.


Blade Seals: Full length vinyl weather strip

Sturdily constructed from all aluminum extrusions

Roll form blades or extruded aluminum blades.

Available In any combination of width and height.

Less than 1% leakage.

SR: 0.016" - 0.020" roll formed aluminum with Vinyl gasket - used with fan motors that are 3/4 HP and lower.


*NOTE: Please select outward or inward mount by selecting from the drop-down box above.

DIMENSIONS: 23" x 23" x 2.5"

20" x 20"

Model No.:
SR3220X20 -RUSH
Made In U.S.A.:
Dampers, Shutters & Weather Hoods
Blade Material:
Limited Warranty:
1 Year Limited Warranty
Notice: Manufacturer's products features and specifications are subject to change without notice.
California Residents: warning WARNING- This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, please visit


Ask a Question
  • are the moving edges covered with felt to close quietly, eliminate clanging? what is warranty?

    This shutter offers a vinyl strip on each blade that helps seal and reduce chatter.  Warranty is 1 year against manufacturer defects.

  • Why is the pull chain recommended?

    The pull chain is only if you are not using a fan in front of this shutter to blow it open. The pull-chain allows the shutter to be opened manually for air movement.

  • What is max CFM this can handle? Is this manual intake fan weather-proof? Does it have a bird/insect screen?

    This Shutter / Damper is to be used with fans utilizing 3/4 HP motors or lower. This is not a fan, but does close automatically when the fan that blows through it is turned off. This Shutter / Damper does not come with a bird screen.

  • how do keep insects out

    Insects can not enter when fan in On, and when fan is turned Off the shutters drop closed.