Extractor fans

[Chris J Dixon]

My Manrose SF120T (125 mm in-line fan) sounds, from intermittent bearing noise, as if it is about to fail.

Although the two I have had so far have given reasonable life for an inexpensive item, I think it is time to consider a more robust model.

I am looking for a quiet, capable, 125 mm duct fan, with run-on timer, to fit into existing flexible ducting for my bathroom.

The MF125T looks the best match, but I am waiting for a response from the supplier about its high/low speed configuration. Does anybody know if it is possible to permanently connect in low speed without the expense of the separate speed control box?

Chris

[rbel]

You may want to have a look at the quiet S&P in-line units

We have one for a bathroom/shower extract and it seems to be an improvement on the Manrose equivalent and has a noticeably better noise/air movement result.

As a kitchen extract we have a two speed in-line Vent Axia (without timer) ACM 125 which is somewhat noisier but is effective and very easy to demount for cleaning.

[Chris J Dixon]

Thanks for that, it looks interesting, if a little expensive. I hadn't found it on TLC's site when I looked, as they don't list it under "Shower & Inline Duct Fans"

Chris

[meow2222]

You can speed reduce a fan with a series capacitor. However no mfr will rec ommend starting a fan on reduced setting, it significantly increases the on set of failure. A possible solution is a 3 position switch or a time delaye d relay (diode, RC) so the fan comes on at full then quickly switches to re duced speed.

Surely fruiting trees are more use

NT

[polygonum]

recommend starting a fan on reduced setting, it significantly increases the onset of failure. A possible solution is a 3 position switch or a time delayed relay (diode, RC) so the fan comes on at full then quickly switches to reduced speed.

Not sure fruit is any more use than sugar, is it?

[SteveW]

Is it not possible to replace the bearings?

SteveW

[meow2222]

Maples produce dilute sap that takes time & skill to harvest, and is a right hassle to concentrate into syrup. Hence I know no-one that does it. Fruit OTOH is immediately usable by most people, and used by a huge number.

NT

[Chris J Dixon]

recommend starting a fan on reduced setting, it significantly increases the onset of failure. A possible solution is a 3 position switch or a time delayed relay (diode, RC) so the fan comes on at full then quickly switches to reduced speed.

As it happens, in this particular case, the real answer is different. Manrose has just advised:

"Yes it is possible to permanently wire the MF125T to the Low or High speed setting without using a speed controller. When you wire the fan up place the Neutral wire into the terminal marked S1(sometimes denoted as N1) on the fan for the low speed or S2 on the fan for high speed (sometimes denoted as N2)."

Life is a bit dull when confined to utility.

Chris

[meow2222]

recommend starting a fan on reduced setting, it significantly increases the onset of failure. A possible solution is a 3 position switch or a time del ayed relay (diode, RC) so the fan comes on at full then quickly switches to reduced speed.

Fair enough. It won't last as long that way, hence fans are always started at full power initially by controllers.

NT

[Chris J Dixon]

full power initially by controllers.

You seem to be discounting the possibility that the motor winding has been specifically designed for just such performance.

Chris

[meow2222]

full power initially by controllers.

If the manufacturer says its ok, then its reasonably obvious that it has been designed to do the job. That of course has no bearing on the reality that it will start with less torque at this setting, thus fail earlier.

NT

[Andy Champ]

designed to do the job. That of course has no bearing on the reality that it will start with less torque at this setting, thus fail earlier.

If it gets a bit stiff in its old age, and won't start, doesn't he just need to move it to the other setting to give it a kick?

And if it's running at low speed for the moment won't it take longer to wear out its bearings to the extent it needs the kick?

Andy

[newshound]

In principle; they are usually self aligning oilite bushes but the carriers often seem to be motor-specific. A spray of WD40 or similar often quietens them down for a good while, or a dribble of 3 in 1 provided you can get it in just the right place.

[meow2222]

been designed to do the job. That of course has no bearing on the reality that it will start with less torque at this setting, thus fail earlier.

If it hasn't fried itself or caught fire, yes. But they often fry, and sometimes burn.

NT

[meow2222]

WD40 is a solvent, white spirit. That frees it up temporarily, but soon eva porates, just leaving less lube in the bearings. Ideally what's wanted is t o clean out and regrease the bearings. Next best is lots of oil, sometimes that works well enough, sometimes not.

NT

[Andy Champ]

Ah. I've always had fans fail the "unacceptably noisy" test first. Perhaps computer fans are built to different specs. (I used one for many years in an extractor... until it got too noisy)

Andy

[Chris J Dixon]

Finally got round to fitting it, which involved contortions in the limited roof space.

It really is quiet, you actually need to feel the airflow to believe it is running.

Chris

[Lobster]

Well at that price it needs to be!

I fitted a cheapo, allegedly silent model in our roof space years ago, for our en suite; it quickly became apparent that 'silent' it was not. Naturally I was charged with the task of replacing it; however it was fortunate that that particularly round tuit never came home to roost, since SWMBO actually likes it now, as a white noise generator - firstly, to conceal bathroom 'noises' which apparently girls don't like (either their own or other people's) [1]; secondly, to muffle any 'bedroom' noises from us, which becomes an issue when the kids are old enough to stay up as late as you do, and thirdly, to drown out the noise of squabbling teens downstairs if she's having an early night.

So, no more plans to change the extractor...