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Noisy Extractor Fan


expat paul
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Hi,

I've a noisy extractor fan, its one of those in-line fans which sits in the attic just above a shower, comes on with the light and goes off after 10mins. At the moment it is mounted on a piece of wood which spans two ceiling joists, and it runs virtually silent if I unscrew it and hold it.

 I've been looking around for some sort of anti-vibration mounting but only found large ones ie car engine  and exhaust mounts, a bit of over kill for a small fan. Anybody got any bright ideas ??

thanks

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A normal synchronous motor (most smaller fans have these) should make little noise or vibration.

It may well be the fan.

Thus the first port of call should be to remove the blade and check it for rotational balance and squareness; (i.e., it may well be in rotational balance, but part - or one blade or two -  might be throwing out of true, which can cause what is known as a moment of inertial imbalance).

Easy way with a simple axial fan is to sit the blade assy on s shaft similar in size to the motor shaft, but with no grub screw and see if it rotates until one part is at the bottom.

If all is not too far out of balance then use something like these. and These.

They are available in all sizes and are simple blind studs moulded into a synthetic rubber bush; one stud on each size.

 

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So much for the good practical advice. Now for some advice from those with faith in the power of the human mind: appeal to the fan which must have a better nature, and try to find out spiritually why it is unhappy, then, if that fails because it is Chinese and doesnt understand you, threaten to strip it down and rebuild it with bits missing (you can do this using mime and gesture). Alternatively, the threatened use of rubber may be enough to stop it singing, especially if it a Catholic fan that likes to feel raw materials rubbing together.

If all else fails, show it the bin.[6]

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[quote user="Gluestick"]

If all is not too far out of balance then use something like these. and These.

They are available in all sizes and are simple blind studs moulded into a synthetic rubber bush; one stud on each size.

 

[/quote]

Any idea where I would find small ones of those here in France, all I have found car engine and exhaust mounts which are massive comparatively. Are mounts like that used on motorbikes quads etc ?, I'm thinking they might be smaller

ps I have tried grommets and rubber pads this afternoon, a little better, but the screws still transmit the noise through to the wood. Haven't tried giving it a good talking to yet, just swearing [:)]

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Specialist automotive outfit which supplies parts for race cars.

We used them all the time for mounting things like oil tanks. Since on single seaters engines are mounted direct on the chassis, the vibration levels can be awesome.

There must be some racing nuts near you?

 

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Does this obviously unhappy fan need to be screwed down onto a bit of wood ? The wood is acting as a sounding board and amplifying the noise. This is then sitting on the stiff joists which are probably trying to join in.

We have such an in-line fan taped down by and across the inlet and outlet tubes onto a small sheet of left over cushioned vinyl flooring (a bit like old lino which happens to have a bit of foam backing) which I've folded over a few times to stiffen it up a bit. I've used duct tape which is an original use for it and probably a first !

It wasn't designed, I just grabbed what useful bits I could find in the garege and did it all in about 20 minutes. It's been fine for a couple of years now.

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Well done Clair, you beat me too it!

The VMC fan housings have suspension lugs so that they can be hung from the madriers, when mounted like this they are virtually noiseless.

Get to work with some string or if you want to be really posh some suspension wire K.I.S.S. [:D]

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