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Square galvanised steel frame with aluminum backdraft damper panel 25 by 25 inches

Dayton

Dayton 4HX67 Roof Mount Damper 25 Inch

SKU CH-PV4T-AWN5S

Aluminium back-draft damper with galvanised-steel frame mounts on a 25-inch square roof curb and handles air velocities up to 2,250 fpm

  • TypeRoof Mount, Exhaust
  • Roof-mount exhaust damper prevents backdrafts
  • 25-inch square frame fits 20-inch fan openings
  • 9 sq ft free area allows high airflow
  • Galvanized steel frame with aluminum blades resists corrosion
  • Rated for air velocities up to 2250 fpm

25-Inch Aluminium Backdraft Damper

The Dayton 4HX67 is a roof-mounted exhaust damper built from aluminium blades inside a 20-gauge galvanised steel frame. It fits a 20-inch fan and covers a 22 1/2-inch square rough opening with an overall height and width of 25 inches. The unit provides 2.9 square feet of free area and handles air velocities up to 2250 fpm.

Suited to gravity-relief exhaust on flat roofs

This damper serves installers who need a single-panel backdraft closure for a square duct penetration. It is not intended for supply-air intake, motorised actuation or round-duct connections, so buyers needing powered operation or a circular flange should look elsewhere.

Steady airflow within rated velocity range

Under sustained exhaust flow the aluminium panels pivot open and remain stable as long as face velocity stays below 2250 fpm. The 2-inch frame depth and 4 1/2-inch overall length keep the assembly compact while maintaining the 2.9-square-foot free area during continuous operation.

Highlights

  • Roof-mount exhaust damper prevents backdrafts
  • 25-inch square frame fits 20-inch fan openings
  • 9 sq ft free area allows high airflow
  • Galvanized steel frame with aluminum blades resists corrosion
  • Rated for air velocities up to 2250 fpm

Specifications

BrandDAYTON
TypeRoof Mount, Exhaust

Questions about this item

What square rough-opening size must my roof curb provide for the 25-inch Dayton 4HX67 damper?

The damper requires a square rough opening of 23 1/2 inches by 22 1/2 inches to fit correctly.

Will the single aluminum panel close tightly against a 20-inch fan housing when the fan stops?

Yes, the backdraft panel is sized for a 20-inch fan diameter and uses gravity to seal when airflow ceases.

How can I confirm the damper is operating properly after installation?

Run the fan at up to 2250 fpm and verify the panel opens fully; when the fan stops, the panel should fall shut with no visible gaps.

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