>> A fan pushes air forwards by using flat blades to fan it. An impeller 
>> pushes air *outwards* by centrifugal force. That's an entirely different 
>> mode of action. (Although of course impellers aren't exactly new either.)
> 
> It is the reverse mode of action.
> 
> My computer's power-source has what I would call a fan. In fact, everybody I 
> knows calls it this. Yet it impells air into the unit. So should it be named 
> impeller?

A fan works by having blades with a uniform cross-section, but angled to 
accelerate air parallel to the plane of rotation. If you spin the blades 
one way, it blows forwards. If you spin them the other way, it blows 
backwards.

An impeller uses centrifugal forces to blow air *outwards* (i.e., away 
from the center of rotation - usually meaning that air is sucked into 
the impeller through a port near the center and exits the impeller from 
the edges). If you spin the impeller the other way, the air still flows 
in the same direction.

>> What _is_ new is that by using clever air currents, you can make the draft 
>> much bigger with less effort. And I guess it looks kinda neato.
> 
> Yes. That's what caugt my eye. It does look good, and at first glance one 
> wonders how it is done. Hence my disappointment when I found out. ;-)

I can understand that. ;-)

>> From what little I've seen, fans tend to get dusty when they're not in 
>> use, because they're exposed to the air. An impeller, by definition, is 
>> internal. When it's not running, there's very little air to get it dusty.
> 
> Look into your computer. If it is older than a year, examine the fans. Now, 
> that is what I call dirty.

True. Then again, the entire inside of my PC is carpeted in dust; why 
not the fans? I guess somebody more qualified than me can explain why 
fans get dusty...

>> Still, at the end of the day, if you don't like it, don't buy one. :-)
> 
> Have you looked at the price? $329.99 - this is surely innovative. ;-)

Ouch! o_O

OK, definitely don't buy one...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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