AC Infinity4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans

Installed in an 8 inch downdraft for the stove. So the previous few months were well below winter average temps, always had a draft (very cold) entering the house. Installed and immediately ended the draft. My electric usage was very high during the frigid weather. I'm guessing I saved $3 a day in energy savings. Also purchased three 4" back drafts for the bathroom vent fans. They also allowed energy loss, melted the snow on the roof, creating ice in the gutters. Glad they didn't collapse, big $$. If you mount horizontally, I recommend keeping the axis horizontal as well, which will provide a higher centering effect while functioning.

Worked perfectly

We get tons of wind where I live. The bathroom vents in our house clicked constantly as the wind caused the built-in plastic dampers to flap closed with a wind gust (normal bathroom vent dampers are OPEN by default--- more on that in a second). When it's cold wind it would take our bathrooms down a few degrees and make the tile floors cold and uncomfortable.I bought one of these spring loaded dampers and installed it. Getting into the attic wasn't fun; but, oh what a difference. No noise at all, and it warmed our bathroom right up. I liked it so much, I ordered one for each bathroom and installed them.Considerations;1) It does seem to slow how quickly the fans clear the rooms--- but not significantly, might take an extra minute or so. We actually have timers on our fans so that's no problem... just push a longer time and walk out. Highly recommend timers, even if you don't use these.2) I have a new home, it's very air tight. Those bathroom fans are a huge part of how fresh air enters new homes, which is why the dampers are usually OPEN, only closing with a gust of wind. Gusts below a certain threshold will go right through them. SO--- If you are going to block the bathroom vents up with dampers, you need to make sure you have OTHER means to get fresh air into the home and humidity OUT, especially in new construction homes. I highly recommend looking at an fresh air damper (very cheap), or Enthalpy or Heat Recovery Ventilator (ERV/HRV) for your HVAC system.

The spring may be slightly too strong depending on the application. Other than that this is a very nice build quality and I’ve used them 2 times. It worked good for a 50 to 80 cfm project I did. If insulating around this piece be careful not to foam or tape over the hinge pin.

The damper opens fully when fan comes on and closes quietly when fan shuts off. It is sized to fit the inside of a 4" meal duct and not the tapered end.

This is an excellent, very well made backdraft damper. Powder coated in black with exterior rubber seals to hold itself in place in 4 inch duct work. The dampers also have foam seals they rest on when not forced open by the dryer running.I use these for dryers that have exhaust vents that allow cold air into the laundry room in the winter -- and allows cold to escape thru the dryer exhaust vent when it is not in use in the summer. This backdraft damper is easy to install into the existing standard 4 inch dryer exhaust vent duct. Merely remove the vent hose from the exhaust duct and slide this damper in, making sure the dampers open from inside pressure from the dryer when it runs. The dampers should flip outward toward the exterior of the exhaust vent when you press on them. Most exhaust vents have plenty of room for these dampers.

Much better quality than other models. Seals well and has spring return.Update: Purchased three time so far and very happy with the quality.

I have a modest 45 CFM, 0.3a fan; with Well sealed ducting, and that fan struggles to open this. Little aggressive guys.Definitely does it's job, but it's going to lower your flow significantly.