AC Infinity Backdraft Damper for 4" Ducting

I needed some sort of back draft prevention for my bathroom vent fan setup because I was getting bugs and draft in my basement bathroom. These fit right up to other 4 inch ducting, and I used rubber connectors to secure these on. They look sleek, work great, and they have a great quality seal and don't let air back in. They have a double flap to prevent back drafting. I used two of them in my set up to keep each line isolated before a combining y connection

Very precise, quality made product that fits nicely into the 4” flexible, insulated ducting.

I needed to create an exhaust system for my 3D printer so I purchased the AC Infinity cloud line in-line fan along with this backdraft damper since my exhaust leads directly outdoors. One thing I noticed is that the springs on this damper are pretty stiff so it requires a decent amount of airflow to push the damper flaps open. Using the cloud line S4's speed controller as a reference, the flaps didn't open until I got to level 4. The reason this may be an issue is because in temperature controlled environments (like printing certain types of material) you don't want your in-line fan to be too strong otherwise it will cool your chamber too quickly. Aside from that, the damper is constructed well and will likely last a long time. One other thing to note, I bought the 4" damper and with 4" ducting it is a very tight fit to get the ducting around so it does create a decent enough seal. Overall works well but if you only require a low airflow system like me I would recommend testing this out first before fully installing.

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.

Worked just like it should!

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.

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.

This is a fantastic unit! I installed a new Broan bathroom fan but noticed that the included damper was horrible. It wasn’t closing properly and had a 1/8” gap around the edge so it was still letting in lots of cold air. I removed the Broan damper (piece of plastic) and put this unit in line instead. 100% improvement and zero cold air coming through now. The unit is black in color with a rubber gasket on each end for your ducting to slide over. The unit itself feels like it’s got some dampening on it because it’s not as tinny as other units. The butterfly closure has the right strength to it...easy open and easy close. There is an internal ridge where the butterfly flaps close up to so there’s no big gap like the Broan model. Very, very happy with this unit and now our bathroom isn’t freezing anymore. Worth every penny!