Where an 8 inch Backdraft Damper Earns Its Place
Eight inches is where a lot of single room extraction ends up. It is also the size where backflow starts costing money rather than merely being a nuisance. A duct this diameter moves a serious volume in either direction. With the fan off, an eight inch open run will let cold air, smell and roof dust travel back into a room all night. Sealed rooms lose their pressure relationship the same way. This damper stops that with two galvanized blades hung on independent hinges. Independence is the part to look for in any damper, because a shared shaft turns one stuck blade into two. The whole assembly inserts into the duct, so there is no flange, no adaptor and no transition piece. It installs in any orientation, which matters on a vertical riser as much as on a horizontal run.
The Neoprene Gasket and What a Bad Seal Costs
The blades close onto a neoprene perimeter gasket rather than onto bare steel. That choice does two jobs at once. It takes the clang out of a closure, which is a real consideration in a building where people sleep or work nearby. It also fills the gap that a metal edge always leaves. On a duct this size a thin gap around the circumference adds up to a meaningful leak. Keep the gasket in mind through the life of the installation. Dust builds on the sealing face, resin from a room carries into the duct, and a face that cannot seat cleanly leaks quietly for months. Wipe it when the filter is serviced. Atmosphere quote an opening requirement of four to eight hundredths of an inch of static pressure. Any reasonably specified eight inch fan exceeds that at full speed. Check it at the lowest speed the fan will actually be run, not at full.
Key Features
- Duct size: Eight inches, which covers most single room extraction runs
- Function: Prevents backflow of cold air, odour and dust when the fan stops
- Blades: Two galvanized blades, each on an independent hinge
- Seal: Neoprene perimeter gasket, not a bare metal edge
- Noise: The gasket takes the clang out of every closure
- Leakage: A gasketed face closes the gap a metal edge always leaves
- Mounting: The assembly inserts into the duct with no flange needed
- Orientation: Any position, including a vertical riser
- Opening pressure: Four to eight hundredths of an inch of static
- Maintenance: Wipe the sealing face whenever the filter is serviced
Technical Specifications
| Specification | Value |
|---|---|
| SKU | VTBDD8 |
| Duct diameter | 8 in |
| Brand | Atmosphere |
| Type | Round backdraft damper, duct insert |
| Material | Galvanized steel |
| Blades | Two, each on its own independent hinge |
| Seal | Neoprene perimeter gasket |
| Mounting | The whole assembly inserts into the duct |
| Orientation | Installs in any position |
| Opening pressure | 0.04 to 0.08 in of static pressure |
| Designed for | Atmosphere Vortex in-line fans and dryer exhaust ventilators |
| Barcode | 628507200046 |