AC Infinity 4" 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.

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!

Looks good with nice paint, but has some UNFIXABLE design issues. Quality and design issues. Spring jams in hinge of flap on 4 inch. The shaft and the hinge fabrication/design are not right and causes the flap's hinge tab to pinch the spring inhibiting motion and sometimes the leg will get stuck in the hinge and not work at all. The spring is TOO weak and does not fully close the flaps;( same with 6 inch. No gasket to silence clanking flap. Out of round in the center at the flaps lets air through.; on BOTH the 4 inch AND the 6 inch. lastly, Why gaskets on the connections which are really only effective on rigid ducts. They will be taped anyway!UPDATE: received a replacement 4 inch. Same problem with out-of-round housing. See pic. Flaps jam/stick. Put a clamp on the housing to squeeze it round and the flaps work fine, so definitely sticks because housing is out-of-round. Need to dis-assemble and press the housing to make it permanently round, but cannot dis-assemble because hinge pin is not removable since its ends are CRIMPED. Mfgr is sending ANOTHER one and they will check it befor eit leaves warehouse. Stay tuned.