Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!knuth!mjbtn!raider!elgamy!elg
From: elg@elgamy.RAIDERNET.COM (Eric Lee Green)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: The Fanning of the Amiga
Message-ID: <00676835659@elgamy.RAIDERNET.COM>
Date: 13 Jun 91 17:54:19 GMT
References: <3025@public.BTR.COM> <3004@public.BTR.COM> <1339@cbmger.UUCP>
Organization: Eric's Amiga 2000 @ Home
Lines: 71

From article <3025@public.BTR.COM>, by thad@public.BTR.COM (Thaddeus P. Floryan):
> In article <1339@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes:
>>told us: When the fan sucks the air out, it is much more possible to
>>direct the flow (by choosing inlet openings) to areas inside the case
>>that need cooling (processor, expansion cards,...), than it would be
>>possible with a fan blowing into the case (please don't ask ME for
>>details, I'm only a physicist... :-).
>>[...]
>
> As a for-instance, I can look at ANY one of my Amigas at home or at the office
> and clearly see where the air enters the systems due to:
    [dust]

I'm just curious. I'm not such a fastidious housecleaner myself, but I
haven't had this rampant dust buildup that you so decry. Every time I open
the case I make a swipe at it with my wet-dry vac, of course, but last time
I did that was back in February when I installed a BridgeBoard. Do you live
in, like, a high dust area?

>       a fan blowing ONTO a power supply will keep the supply cooler than
>       will a fan sucking air OVER a power supply.

Correction: AIR blowing onto a power supply will keep the supply cooler
than will a fan sucking air over the power supply. Whether that air is
coming from a fan or from a case opening doesn't matter.

> If you want to perform a simple test for yourself, quickly go do some exercise
> and work up a sweat.  Then choose to cool off by either:
>
>       (a) standing in front of a fan blowing on you, or
>       (b) standing behind a fan sucking air around you.
>
> I'm sure you'll quickly agree that choice (a) cools you better!   :-)

Down here in the Southland, before the advent of air conditioning, we
had something called the "attic fan". Basically, it was a huge fan up in
the attic that sucked air through a large opening in the hallway ceiling
and blew it into the attic and thus out the eaves. I remember when I was a
kid, and the attic fan was on. I'd be all hot and sweaty (remember, 95
degree weather and no air conditioning), and the fan would be on, and I'd
stand in front of an open window and let the airflow cool me off. Of
course, I would have first gone and shut most of the other windows! Anyhow,
the effect was even more cooling than standing in front of the fan. At
picnics etc. I'd see similar fans mounted in frames blowing huge gusts of
air, but with it sucking air out of the house, we could get a more
concentrated airflow by shutting most of the windows and turning the house
into a REALLY low-pressure zone. Could get a virtual hurricane blowing
through a window then, far more than could be done by any fan that would
have fit in that window. I haven't seen an attic fan down here in any house
built since 1960. Would be great for spring and autumn and those warm
winter days that hit the 70's down here in the Southland, but homebuilders
down here ignore such things while following "trends" (which, in the
homebuilding industry, tend to be set in places like Massachusetts and New
York, sigh).

In any event, back to the issue in question, yes, fans sucking air OUT of
an area can be quite as effective as fans blowing air INTO an area.
Especially when it's a multi-segmented area such as a house or computer,
where airflow can be easily adjusted by adjusting the "windows". (Ah,
anybody remember reversible window fans? If you wanted to cool one room,
blow air into that room... if you wanted to cool the whole house, blow air
OUT).

> Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]

I assume you've never been a Southerner in the pre-air-conditioner era?
You learn a lot about fans and cooling under such conditions :-).

--
Eric Lee Green   (318) 984-1820  P.O. Box 92191  Lafayette, LA 70509
elg@elgamy.RAIDERNET.COM               uunet!mjbtn!raider!elgamy!elg