bunnings 4w bathroom fans

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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.

Reply to
syd bluemountains
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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.

Reply to
Dennis

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

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Reply to
Dennis

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?

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Krypsis
Reply to
Krypsis

"syd bluemountains"

** 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

Reply to
Phil Allison

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.

Reply to
Dennis

"Dennis"

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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

Reply to
Phil Allison

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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.

Reply to
Dennis

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.

Reply to
syd bluemountains

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.

Reply to
Bruce Varley

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.......

Reply to
Dennis

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

Reply to
Dennis

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