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We have gotten attic rain the last 4 years. This was due to the bathroom fan not being air tight, weak/old fan, and having -30c temperature freezing the humid air and then melting in spring. This would cause water to come through roof.

So I bought a new roof, new vents, and got a new humidity sensing bathroom fan, made it air tight. It is supposed to be 'silent' however it sounds like an airplane.

If I do not have the black actual fan fully inserted into the housing it is fine. If I put it in all the way to secure it, it sounds insanely loud. I have tried re-seating it multiple times, adding foam to dampen the sound but nothing works.

I can't shower when the kid tries to sleep because it is so loud.

What can I do to reduce the noise from this fan?

Some videos of it I posted to imgur. Foam isn't pretty. But it helps keep the area air tight.

https://imgur.com/gallery/QsR2FHL

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    What path does the pipe take after it leaves the fan? (Distances, elbows, etc.)
    – Aloysius Defenestrate
    Commented Oct 11, 2023 at 2:37
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    I see what looks like some texture overspray on non-moving parts of the fan. Adding even a little eccentric weight to the squirrel cage will throw it out of balance and thereby cause vibration. Yeah, I think I see some stuff on the middle part of the squirrel cage.
    – popham
    Commented Oct 11, 2023 at 2:37
  • I will definitely give it a clean and see if it helps. If I don't put the black fan part fully into the housing it doesn't make any sound. When I seat it properly in, then it starts sounding like an airplane. I'm wondering if something in the attic is vibrating against the housing when it goes full throttle.
    – Brian Hamilton
    Commented Oct 11, 2023 at 3:07
  • does it moves axially ? when you push and pull on it? is that new or old problem ?
    – Traveler
    Commented Oct 11, 2023 at 3:39
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    May just be louder because the housing resonates and amplifies it. In which case my answer would be "bearings are probably shot, replace the motor." You may be able to test this by damping the housing's vibration.
    – keshlam
    Commented Oct 11, 2023 at 4:48

3 Answers 3

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From listening to the video, it's obviously a case of the fan blades hitting the cylinder enclosure. With the switch off, move the fan with a pencil until you can see exactly where it's hitting, and from there you can diagnose the issue.

This could be a manufacturer defect, eg the cylinder not being perfect, the fan blades extending just a bit too much, the fan being unbalanced, the fan axle wobbling, the fan motor mounting points getting loose, or the motor bearings being damaged.

It could also be some issue created during installation, creating any of the conditions listed above.

Regardless, it seems that you have spent a lot of time trying to figure this out and have not found the issue. I love fixing things and hate discarding things that can be repaired, even when the repair takes hours to save a few dollars, and even when the parts cost more than replacing. But if the fan defect is not letting your kid sleep, just get a new one. A new, super quiet fan is less than $150 and takes an hour to replace. You can then take this unit to the basement and disassemble it at leisure to satisfy your curiosity as to the cause of the blades hitting the cylinder.

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  • Thanks for the comment I will definitely try it. This is a new fan as of last year. The previous one didn't do anything and needed to be replaced. This was 200$, labelled as a quiet fan. If I don't secure the black fan housing to the actual housing it doesn't make the sound. But if I put it all the way in it sounds like the video.
    – Brian Hamilton
    Commented Oct 11, 2023 at 21:28
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Clean any texture and/or paint overspray off of the rotating cylinder. Even a little eccentric weight on there will throw it out of balance and cause vibration.

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  • I will definitely get up and look close up and clean any additional foam on the rotating cylinder. Thanks for pointing that out. If anyone has any other ideas please let me know. We have delt with it for a year and it's just too much now. I really appreciate all the responses.
    – Brian Hamilton
    Commented Oct 11, 2023 at 3:04
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This is a very common problem for electricians, the amount of times I hear that sound is unrealistic, the problem is the fan blades striking the cylinder casing, the fan must move snuggly into the opening, any pressure on the fan blade cover will course this problem.

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  • you make sense ...+1
    – Traveler
    Commented Oct 11, 2023 at 6:18

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