Flap Exhaust Valves (Flap Stacks)

Regular price $430.35

A resourceful after-the-fan product, flap exhaust valves, or stacks, are designed to open, like bird wings, with the airflow and close when the system is not exhausting. The lightweight and balanced blades produce minimal resistance to exhaust. The design of the housing and blades channel rainwater away from the opening and allow it to drain without intrusion into the ducting. The vertical profile of double flap exhaust stacks is shorter than no-loss stack heads so they require less vertical space.


  • Available in 4" to 32" diameter (contact for custom sizes).
  • Also known as winged stack.
  • Products come with raw ends. Diameters are +/- 1/8 inch.
  • Alternative Solutions: No-Loss Stack, Jet Cap, Rain Cap


*The actual product may differ from the product image.