Repa Market Galvanized Steel 4 Inch Duct Backdraft Damper - One-Way Airflow HVAC Damper, Dryer Vent Damper, Metal Inline Backdraft - 4 Inch Duct Damper, Dryer Duct Connector with Backdraught Flap

Hooked up inline with our hood fan above our stove, prevented back draft of cold air in the winter season. Easy install

Exactly what I needed. I had to make a spring a little bit more flexible, good thing you can adjust it

This damper works, but the spring is very weak. If you tip it anywhere past horizontal the doors fall open, so it can only be installed with the doors facing up or horizontally. Additionally if the doors open all the way to the center, the springs are not strong enough to push them closed again. I haven't run into an issue with this yet, but just noticed during the installation and will need to check at some point to make sure they are not stuck open.

Living in the deep south, after installing a new kitchen exhaust fan the down-draft from the attic was overwhelming. Especially since kitchen exhaust fans are located right over the stove and it is canning season! This item is wonderful. There is no more down-draft at all and combined with my wonderful new exhaust fan my kitchen is comfortable again. At least as comfortable as it can be when I am canning in the summer time in the deep south ;) Great product, shipping time was fast, installation was easy. Thank you!

Perfect, really does what it is meant to do. I have two bathrooms that I connected to the same exit vent with a y connection, and noticed that when one bathroom vent was on, the other would get some of the air going out. I put these in and neither bathroom gets the back flow any more.

The backdraft blocker/damper is of good design and solid construction that I expect to work in the ventilation system trouble-free for a long time. But, the problem is its poor workmanship, leaving many gaps in the valve hinges and between the valves & the form ring around the valve flaps. With so many gaps, the product hardly blocks draft from backing up into the vent pipe & into the kitchen when the ventilation fan is not operating - and I can’t have the fan blowing all the time. I ended up taking the damper down, plugging the gaps with pieces of wax paper cut to size along the hinges, and moving the form ring to be closer in line with he valve flaps - see photo with the wax paper plugs. It now works beautifully. But I’m still worried how long the wax paper will stand the grease and high temperature of the kitchen fume. The workmanship needs to be much greatly improved to overcome these details.

Worked great. As described.

Had an issue with hot are back drafting through my bathroom exhaust vents during the summer time and cold air coming through in the winter time! These stopped that issue. Seal in the inside ensures unwanted air stays out of areas you don’t want it

This is a good bit of kit, I bought it to fit in a relatives apartment complex between a permanently running fan and the common extraction ducting to stop cooking smells back feeding into his apartment. Although it made a massive improvement the shut off not being airtight (as I was aware when buying) still allowed some odour, (I thought it would be so little to be unnoticeable) I later found out the fan was miswired and had a trickle mode rather than on off which sorted the problem, but this non return valve was spot on other than the above consideration.

Perfect draft stopper. No more air blowing back inside my dryer so that means my house is now warmer

Unseviceable.

Perfetta, ha risolto il problema di afflusso di odori sgradevoli dall'esterno, ottima valvola di non ritorno. Grazie