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Discussion Starter · #1 ·
We installed Panasonic bathroom fans in a property and when there is a slight wind outside, the pressure drop will ever so slightly pull on the plastic flappers just enough so they come up and then back down with a little thud. It sounds sort of like having a constant drip of water falling.

Does anyone have a good method for applying weights or some kind of noise dampening from inside the fan while it's installed? Removal is not an option. The ceiling fans were locked in place when they spray foamed, so it would be a major endeavor to remove them and would involve cutting out a lot of drywall around them. In other words, that's not an option at this time.
 

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Is there a spring on the backdraft damper missing? Or a foam strip?
Does the vent exit into any type of baffle to prevent the wind from causing too much backdraft?
 

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Yeah it's annoying. Inline dampers help and the flush exterior dampers don't pick up in the wind like hooded ones
 

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Discussion Starter · #4 ·
Is there a spring on the backdraft damper missing? Or a foam strip?
Does the vent exit into any type of baffle to prevent the wind from causing too much backdraft?
The damper I am referring to is the built-in plastic, non-spring loaded damper installed on the Panasonic fan itself. I do not believe there is a phone strip, because I can hear the sound of plastic touching plastic. The vent exits to the roof which has the standard Home Depot purchased style damper with built in flapper style damper.

What is happening is that slight air pressure changes in the roof are causing the fan's built in plastic damper to ever so slightly lift and then drop. I'm mostly asking if anyone knows The Panasonic fans, and how to get to the fan's damper without removing it. I can fix it if that's the case.
 

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Carpe Diem
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I just installed a Panasonic Whisper fan on Saturday. It's been windy the past 2 days. Not a single flap. You can access the flapper from inside. Pull down the vent cover, you can unplug the motor and with 3 or 4 screws drop the motor assembly. Should be able to see flapper and add some foam between the it and the plastic housing.
 

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Discussion Starter · #6 ·
I just installed a Panasonic Whisper fan on Saturday. It's been windy the past 2 days. Not a single flap. You can access the flapper from inside. Pull down the vent cover, you can unplug the motor and with 3 or 4 screws drop the motor assembly. Should be able to see flapper and add some foam between the it and the plastic housing.
Perfect. That's what I'll do. Yeah, I didn't expect this to be the case given that there is a damper on the roof vent. Although, I hate those cheap Broan Nutone roof vents and most of what you can get walking into a big box store. We just didn't have available to us higher quality options due to COVID related backups in shipping.
 

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We have changed out the exterior vent with a flap vent and removed the fan vent flap and it works great. It takes the flap vent to the exterior side of your home which is now muffled from the distance. The flaps that look like a window blind and not on a pendulum access point work best. Two Center points of contact on the flap will seem to always flap when windy.

good luck.
 

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I just installed a Panasonic Whisper fan on Saturday. It's been windy the past 2 days. Not a single flap. You can access the flapper from inside. Pull down the vent cover, you can unplug the motor and with 3 or 4 screws drop the motor assembly. Should be able to see flapper and add some foam between the it and the plastic housing.
Keeping the expanding foam away from the flapper itself, and its swing radius, of course.
 

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Discussion Starter · #10 ·
We have changed out the exterior vent with a flap vent and removed the fan vent flap and it works great. It takes the flap vent to the exterior side of your home which is now muffled from the distance. The flaps that look like a window blind and not on a pendulum access point work best. Two Center points of contact on the flap will seem to always flap when windy.

good luck.
This was my preferred option when installing the bathroom fan in the first place, following the logic of the range hood manufacturer who recommended installing an in line roof damper over their plastic damper. I chickened out on removing the bathroom fan's similar damper when installing it.

I should point out that this is the slim line Panasonic fan meant to fit in tight spaces - it's oval shape rather than circular.
 

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Discussion Starter · #14 ·
Here is the situation based on photographs I took from another Panasonic whisper thin fan. Because the flapper is in a vertical teeter type setup rather than those bifold style you get with round backdraft dampers, it's easily pulled up with the slightest amount of air pressure. Every time it comes up just a little bit and falls back and hits that little metal stopper, it makes that annoying sound.

510412
510413
 

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Carpe Diem
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Touch of weather strip foam on the flapper where it hits the stop. Done.

See pic I posted above 👍
 

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Reach in with a caulk gun and put a small dab on the bottom side for weight.


Sent from my iPhone using Tapatalk
 

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Carpe Diem
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You have to address where the flap hits the stop. Adding only weight will make the bang louder unless you dampen the cause of the sound.
 

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You have to address where the flap hits the stop. Adding only weight will make the bang louder unless you dampen the cause of the sound.
Depends on the size.

Big enough, it won’t move if it’s windy outside.


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It shouldn't be moving that much in the first place. However, his is moving. Because the percentage of that noise happening is already high, it would behoove him to stop the noise instead of trying to weigh the flapper down. If you were trying to eliminate the potential for the sound to happen, I could see adding some weight. (y)
 
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