The FAMCO BD Butterfly Backdraft Damper is used as a back draft damper for heat exchangers, exhaust systems, solar heating systems and other intake or exhaust applications where a powered damper is not needed. This damper works in both horizontal or vertical positions and the foam seal provides minimal air leakage. Due to its unique design and Aluminum blades, it opens easily with normal air flow and closes with gravity. Quality constructed Galvanized steel, gauges 28 to 22. The FAMCO BD Butterfly Backdraft Damper comes in sizes 4 inch, 5 inch, 6 inch, 7 inch, 8 inch, 10 inch, 12 inch, 14 inch, 16 inch, 18 inch and 20 inch. Spec sheet available for download. The FAMCO BD Butterfly Backdraft Damper is manufactured by Famco in the United States and comes with a 1-year warranty against product defects and workmanship. If you have any questions about this damper, please refer to the FAQs above or feel free to contact us by phone or email.
Watch the product video on YouTube.
SECURE ONLINE PAYMENTS FAMCO takes Online Security very seriously and uses the most trusted names in the business to secure your online payments. The presence of the 
OUR PRODUCT GUARANTEE FAMCO prides itself on Quality Built Products manufactured from quality raw materials. All products are guaranteed to be free of defective material or workmanship for a period of one year from the date of delivery. During the guarantee period, if any parts prove defective, they will be replaced free of charge. Please click 
Bob –
4″ Butterfly damper perfect for “supply air”
We use these when sealing a crawlspace or attic. As an insulation contractor, we use spray foam to encapsulate & insulate these areas for homeowners. The 4″ damper is inserted into an HVAC supply plenum, so that the HVAC conditions the area, and aids in the control of high RH.
Sheila –
Excellent quality and service
FAMCO has excellent customer service and their product is always exactly as stated. Our company has ordered several of the 6″ dampers and they work perfectly.
Sheila Lenz –
Butterfly Backdraft Damper
This is a very good product. It is made to specifics and is exactly as stated.
We are doing a fairly large industrial project and have purchased several of these this year. We have had no problem with this product.
lvmopt –
Excellent 4 inch backdraft vent
This item fits well and does its job. Very happy.
Leonard Ford (verified owner) –
Works nice.
Amrish Patel (verified owner) –
keven nguyen (verified owner) –
Item is well built and sturdy. I’m using this to built a whole house fan. Shipping was fast too! I would recommend buying from FAMCO.
Stephen E. (verified owner) –
I haven’t installed it yet but it looks great
Well constructed and operates very smoothly
Great communication letting me know as things happen and very fast service
R ALLEN (verified owner) –
Built and shipped quickly. Plenty of email notices to keep me updated. Thanks!
Blaise M. (verified owner) –
Excellent product. Easy to install.
Anonymous (verified owner) –
Very well made. Would buy it again
steve s. (verified owner) –
good price quality and fast shipping
Daniel S. (verified owner) –
Product works as designed.
Steve Morley (verified owner) –
Well built, on time delivery. I like these products. Better than the local products.
John B. (verified owner) –
Steven (verified owner) –