I installed this exterior vent for our oven extractor fan

Exterior Fan Vent

However, the metal plate in the vents keeps swinging open and closed when it gets windy and we can hear it in the house to the point where the constant clanging is annoying. I added some rubber washers and foam around the inside of the flap, but the annoying clanging has become an annoying thudding.

I had thought about adding some weight to the flap, but don't want to risk a flap that doesnt open as it should. Is there a way to resolve this or perhaps even another exterior wall vent that I could/should use to resolve this?

  • Vent hoods have a much higher CFM rating, so I'm sure the back pressure from a spring loaded damper won't be as bad as it was for your bath exhaust fan setup
    – Anna
    Commented Mar 17, 2019 at 20:10

2 Answers 2


I think you just need to find a better built vent hood. The first one I found searching on HD specifically calls out this problem in the description:

Unlike other versions that tend to rattle in the wind, the back draft damper on the ProMax cap has been designed for noise and wind resistance and its stylish wide mouth appearance helps to optimize the airflow.

Try shaking it and moving the flaps in the store to see if they make a noticeable sound.


Reconsider a weight. A solution I've used for both my bath fan vent as well as dryer vent is to glue a nut (machine bolt type) as a weight near the lower flap edge. However, my particular dryer run is very short - a few feet, and the bath vent run is no more than 10 feet with a 70cfm fan. The vents run well with very little added back-pressure. I used Goop for glue.

Your oven fan may not have a high cfm, so I'd recommend temporarily taping a smaller nut on first to observe the back-pressure difference while running the fan, and then keep going larger.

Sometimes in the winter if I know a very windy stretch of days are coming, I temporarily screw in a matching machine bolt to my dryer nut, but I don't recommend that unless your memory is good enough to remove it before use.

Also consider a vent like: http://store.heartlandnatural.com/category_s/47.htm with spring kit accessory. I used that for a rental bath vent new installation once with the purpose of keeping critters out. Found vent at Menards and had to order spring kit online. But even with the spring kit, there was more back-pressure than I cared for with a 50cfm bath fan and 15ft run, although still functional.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.