bunnings 4w bathroom fans

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http://www.greentopia.com.au/Energy-Efficient-25cm-Exhaust-Fan-Arlec/MEF25.htm

bought this from bunnings $19.    Normal fan is 36w this one has
almost identical flow and only uses 4watts!  90% less power.

I wonder how this motor works?, cant find any info on it.   Its seems
to work quite well!

ps

There is a note in the box that during startup it is normal for motor
to oscillate momentarily and produce a sound.

Re: bunnings 4w bathroom fans

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Thats low power. I want to force ventillate my roof cavity next summer, a
couple of these could be the go.



Re: bunnings 4w bathroom fans

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Ad material - mentions magnetic "air" bearings, efficient blade design but
not a lot more.

 http://www.arlec.com.au/wtyFiles/MEF25/MEF25_A4Flyer_V2.pdf



Re: bunnings 4w bathroom fans
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Id be interested to see just how it works. I think the clue is in the
oscillations prior to normal rotation. I have a friend who is an expert
on electric motors though the ones he works on consume kilowatts of
power. I will see if he has any ideas on these. For $19 I must just go
to Bunnings and buy one. I have a couple of places here where they could
be useful. Wonder if the motor is encased?

--

Krypsis

Re: bunnings 4w bathroom fans

"syd bluemountains"

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** Most likely it is a low voltage brushless DC motor, as used in countless
equipment fans these days, driven from an inbuilt 240V inverter from the AC
supply.

The 4 watts input figure is mighty low for the 100 litre per second flow
being claimed -  I suspect convection might be helping ....

The bit about magnetic air bearings is a furphy - BLDC motors can all claim
the same.


...  Phil



Re: bunnings 4w bathroom fans

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From the ad-blurb:

"Unique motor design utilises permanent magnets to act as air bearings thus
reducing wear on shaft"

You're probably right there Phil, if they worked I would have thought the
benefit to promote would have been lower friction rather than lower wear on
the shaft.




Re: bunnings 4w bathroom fans

"Dennis"
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http://www.greentopia.com.au/Energy-Efficient-25cm-Exhaust-Fan-Arlec/MEF25.htm
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** The magnets in a BLDC motor tend to centre the rotor so there is no " end
thrust"  -  important if the motor shaft is operating in the vertical plane
as it is with a ceiling fan.

IME however, the most common failure with plain bearing fans is due to
drying out of the lubrication used -  mini size fans make horrible noises
and run slow while larger room fans simply seize up tight until one
relubricates the shaft.

BTW:

WES Components have a range of ceramic bearing fans with enormous rated life
spans and very affordable prices.


....  Phil



Re: bunnings 4w bathroom fans

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http://www.greentopia.com.au/Energy-Efficient-25cm-Exhaust-Fan-Arlec/MEF25.htm
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Yep, same experience, combination of lint build up & dry bearings. A clean &
relube and its good for another year or so.



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Re: bunnings 4w bathroom fans
Mine is mounted on the wall vertically to replace a wall bathroom fan.

Seems to work well after the initial 1 second jitter.

It does have a sound to it, like a higher frequency than a normal fan
but could be
my imagination.

If it is a dc brushless fan with 240v inverter it would be good to
hack one to
run off DC via a solar panel.



Re: bunnings 4w bathroom fans

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Yes - especially as I want to buy a couple for getting 70C hot air out of my
roof space in summer. I already have a couple of 4 or 5W panels.......



Re: bunnings 4w bathroom fans

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Every bathroom fan we've ever had has had to deal with a buildup of crud,
sometimes it's that that eventually causes its downfall. With such a low
torque, you'd either be regularly having to take it down and clean it, or
else if it doesn't tolerate stall well it might not last too long.



Re: bunnings 4w bathroom fans

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Since we've tiled every room in the house airborne lint seems to kill
ceiling fans in <2yrs.



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