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Backdraft dampers are a specialized type of damper designed to prevent air from flowing the wrong way in an air duct. Often thought of as check valves for ductwork, backdraft dampers keep air flowing as it should. High-quality design and attention to detail are the keys to building reliable, easy-to-maintain backdraft dampers.

How Do Backdraft Dampers Work?

Backdraft dampers are designed to open under a certain air pressure with the blades of the damper returning to the closed position as the air pressure decreases. Backdraft dampers serve as one-way or check valves for ductwork, keeping air flowing in the direction it is supposed to and preventing backflow.


Depending on the application and damper design, the blades of a backdraft damper can be linked or independent. Linked damper blades open and close uniformly because they are mechanically connected. Independent blades are able to open and close regardless of what the other damper blades are doing. With linked damper blades, the opening and closing operations are typically smoother but the entire damper can become inoperable if a blade is damaged or becomes stuck.


Blade design and counterbalancing help ensure that backdraft dampers operate as designed. An ideal backdraft damper is able to open quickly with very little pressure drop and close off tightly as soon as the air pressure is decreased. Counterbalancing makes this possible, either by adding counterbalancing to the damper blades or to the arm outside of the air stream.

Blade Seals

Weighted counterbalances help the backdraft damper to seal against air flow, however, additional blade seals are sometimes required. Blade seals improve the surface on the edge of the backdraft damper blade, and allow for a tighter seal to be generated as the damper closes. With blade seals, backdraft dampers can withstand much higher back pressures with less leakage.

Backdraft Damper Applications

Backdraft dampers show up in many locations where airflow needs to flow in only one direction including:

  • Clean air systems

  • Bathroom fans

  • Exhaust hoods

  • Fan walls

  • Industrial Fans

Most exhaust systems will have a backdraft damper included to prevent air from reversing direction. Bathroom fans and exhaust hoods also typically use backdraft dampers since the flow of air through them may not be continuous. The backdraft damper prevents unconditioned outdoor air from flowing into the building when not actively exhausting air.

Many fan wall assemblies utilize backdraft dampers to allow equipment to continue to operate even with the loss of a fan. Fan walls in air handlers (consisting of multiple fans in parallel) use the pressure generated from active fans to open the damper while allowing the backdraft dampers to isolate any fans that may not be functioning properly.

Backdraft dampers can be made in many sizes, shapes, and materials based on the application. Square and round backdraft dampers are very common. Most backdraft dampers are made from galvanized steel with aluminum that can be used in applications needing spark resistance and stainless steel providing corrosion resistance.

American Warming and Ventilating (AWV) Backdraft Dampers

American Warming and Ventilating (AWV) offers a wide selection of backdraft dampers in various frame sizes up to 48” x 96”. Our backdraft dampers are designed to meet any project needs in an energy and cost-efficient manner. Our BD-40, BD-41, and BD-41-HD lines prevent the reversal of airflow for a variety of low-pressure, medium-velocity clean air systems. The sturdy, galvanized steel hat channel frames allow for easy in-duct mounting.

The BD-51, BD-52, and BD-53 lines are designed to prevent the reversal of airflow in low, medium, and high-pressure systems, respectively. Available in galvanized steel, 304, or 316 stainless steel, AWV backdraft dampers are built to last. The BD-53 series is capable of withstanding a max differential pressure of 13.5 in. wg.

AWV backdraft dampers have the look and functionality that you desire. Consider your options, then contact us today for more information.

The Benefits of AWV Backdraft Dampers

AWV backdraft dampers are known for exceptional quality and reliability. With many backdraft dampers operating in service for decades, AWV strives to maintain the quality they have become known for.


AWV products are designed to last for decades. Keeping AWV backdraft dampers operating efficiently requires very little maintenance.

Attention to Detail

Ensuring the longevity of AWV dampers requires a special touch. The AWV manufacturing team is known for their attention to detail and the care they put into every product. Meeting specifications is a requirement that AWV takes seriously so that customers always get the products that meet their needs.

High Quality

Material prices are ever increasing, and many manufacturers cut costs by choosing subpar materials. AWV refuses to cut costs by decreasing the quality of its product. To ensure that AWV dampers can meet the demands placed on them, AWV always focuses on building a better product which is demonstrated in the quality of any AWV damper.

AWV Options and Accessories

AWV has an expansive selection of options and accessories to simplify installation and provide the functionality required.

  • Customizable size depending on application

  • Options to meet leakage requirements (CFM, ACFM, or % of flow)

  • Ability to withstand pressures of 13.5 in. w.g. or higher

  • Manual pull chain or electric actuator available on some models

  • Blade edge seals available for most dampers and applications

  • Galvanized steel, aluminum, or stainless steel construction

Why Choose AWV Backdraft Dampers?

AWV manufactures high-quality, long-lasting backdraft dampers that set the standard for how a damper should perform. With their many decades of experience, AWV can help you find the backdraft dampers that best suit your needs. Reach out to their team of damper experts today to learn more about the best backdraft dampers for your project!