mounting bathroom fans better

Has anyone come up with a better way to mount a bathroom fan so as to minimize the vibration they produce? Seems like the traditional 2 screw mount of the normal NuTone bathroom fans would absolutely magnify any sounds and vibrations produced by the unit.
Would it help to put a stringer on either side of the fan so that vibrations are transmitted to the framing?
I don't want to turn this into a physics exercise so much as learn about better methods used.
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on 5/21/2007 4:59 PM Eigenvector said the following:

There are bathroom exhaust units where the fan is further up in the exhaust ducting so you don't even hear them.
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Bill
In Hamptonburgh, NY
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wrote:

That's a great idea. The bathroom off my bedroom came with a separate switch, and I put a switch in the other one so it doesn't have to be on just because the light is on. I only use that one to get rid of semi-maybe-poisonous fumes from some cleaner I might use every year or two.
The one in the powder room I just unplugged. I can't stand that noise.
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The better quality fans such as the Nutone QT series or my favorite, Panasonic, don't have a noise problem. Look at the sone rating for each fan. Less sones is better. I think a Panasonic 80 CFM fan is .4 sones whereas the cheap fans that builders usually install are 6 or 7 sones.
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Sure I know there are better units available, but that's not really what I'm asking.
What about quieting down the one that already exists?
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snipped-for-privacy@yahoo.com says...

One thing to look at, if it's an older fan -- are the fan blades clean? My last home's bath fan got much quieter when I cleaned off an accumulation of cobwebs and dirt so the blades were clean, smooth, and balanced again.
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snipped-for-privacy@phred.org is Joshua Putnam
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I think you're right on. I note that the cheapest of motors make no noise when running alone. Until the bearings are bad, which takes a long time, It has to be the blade, and if it was once quiet and wasn't bent, it has to be the dirt.
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says...

Well that's not a bad idea, probably would cut down on mildew and dust in the bathroom too.
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The noise is produced by the blower/motor system. Yes, a heavier case and better mounts would help reduce the noise but if the blower/motor system were balanced there would be no vibrations to rattle the case. You can beef up the mounting and it may help but it still comes down to the quality of the moving parts.
A sidebar into fan design. Have you noticed how many holes and gaps even the better fans have in their cases. They certainly don't provide a good vapour barrier and prevent air leakage the way they are shipped. I always cover them up with aluminum foil duct tape sealing both inside and outside, even the holes that I will eventually drive a screw through.

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on 5/21/2007 7:15 PM EXT said the following:

Not only that, but most motors are bolted to a thin steel case which only acts like a resonator for the noise.

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Bill
In Hamptonburgh, NY
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Other than using rubber washers between screws & unit to isolate the noise, probably not much. If the designers didn't design it to be quiet, then you'll have a heck of a time making it so.
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wrote in message

Sounds like this idea isn't panning out. Maybe I should go find some other turnip to squeeze blood from.
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You could try using some rubber mounts or put a rubber block between the fan and joist, but I doubt that will do anything significant. The small cheapo fans operate at higher RPMs than the larger more expensive quiet fans.
Save your efforts for some other project. If you want a quiet fan, then buy a quiet fan. When you go to sell the house potential buyers will notice the difference as their current dwelling will most likely have a noisy fan.
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Well if I had a 100 bucks for a decent fan I'd spend the money on paying down my debt and stick with the noisy sucker I have. I have a feeling you're ultimately correct but that don't mean I won't try.
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You could try a fan speed control such as one used for ceiling fans. Maybe the lower RPMs would make it quieter. Of course there is the risk that the motor may make noise from the use of the fan speed control. That would also mean an additional fifteen or twenty bucks that you could have used to buy a better fan or pay down your debt.
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