Extractor fan installation

John Butler · 27 Apr 2004

I am installing an S&P TD-250 ducted extractor fan. It is very good reasonably priced 2 speed fan but made in Spain so the instructions are not clear. It says that the fan can be installed in \\\"any orientation\\\".
I wonder if it is OK to have the fan extracting downwards? The fan will actually act as a blower drawing air from outside down to a computer enclosure and pointing downwards would be easiest with the least ducting. if not it have to be installed horizontally with an L bed duct to go downwards.

ban-all-sheds · 27 Apr 2004

Let me get this straight - you plan to blow unfiltered, un-conditioned air into a computer enclosure

plugwash · 27 Apr 2004

outside air is probablly cleaner than your average indoor air....

ZenStalinist · 27 Apr 2004

Not a good idea... extractor fan blowing downwards, without a capped outlet (or in this case inlet)? We're in the UK here, one word: Rain.

By the way, have you noticed how AT-Style computers (and a great many ATX computers, the standard isn't well adhered to) cool themselves? It's by depressurization. This means that the air blows outwards, creating a lower air pressure, causing air to be sucked in from surrounding doors etc., and also the lower air pressure results in less ambient heat (less air to heat, heat travels as infrared rays I think...)
In my school we have an extractor fan in the server cupboard to cool it, and that works fine, even though it is a draftproofed cupboard.

plugwash · 27 Apr 2004

agree you need to stop rain getting in i'd say the inlet should preferablly point downlwards and be undercover to stop rain getting in if you do this

securespark · 27 Apr 2004

All other factors aside, yes, you can mount the unit itself in any orientation. I have fitted one myself, and it will function in any position. But of course you will have to ensure that water ingress is not a problem, and observe the flow arrow on the casing. In your case of course, it will be pointing to the room and not away from it if you intend to bring air into the room.

funkydiver · 27 Apr 2004

A mate had a similar "issue" and decided to do exactly as the poster is suggesting... sucking air in using the fan...

He had issues!! Lot's of sh*te being sucked in on windy days, being finely shredded by the fan (leaves, paper, etc) which then contaminated his pc's innards...

He got round it by changing the fan to extract and putting in two air bricks (with fly screen style mesh on the outside) to provide the ventilation / air exchange...

His PCs are still by no means sh*te free, however he doesn't need to check them every week when his processor heat alarms kick in (now more like once every three months)

Big_Spark · 28 Apr 2004

I can concur from PERSONAL experience, when I had all 53 machines running SETI in the spare room the heat generated was enormous. Without any interference the temperature in the room reached over 50C within minutes.

Pulling air in does not work, you need an an assisted source of fresh ambient air, or better still cooled air, but you want more extracted that can be put in to create negative pressure as Zen hinted at.

I know my situation was a little extreme, I had to fit an air-con unit in theloft to cool the room and there are vents drawing off the heat to warm the upper part of the house with thermostatically controlled valves..I posted this once before..

However blowing air onto a computer will not cool it, it will likely cause it to over heat. That may sound counter-intuitive, but if the airflow in exceeds the flow out of the machine, the hot air will form a posket in the machine and it will overheat. I have seen this done several times..once by me!!

John Butler · 19 Oct 2005

I have tested the S&P 250T and it is fine for computer cooling.

BUT it MUST be used to draw air FROM the computer enclsure OUTWARDS to the exterior, as said in an earlier post.

In my case with a pentium 4 3.4 ghz PC in a room temperature of 24C and outside temperature of 19C, a new S&D 250T fan pulling air out of the PC enclosure to the exterior dropped the CPU temperature from 70C to 65C whereas when it was reversed to push in cold outisde air at 19 C into the PC enclosure the PC CPU temperature rose to 75C.

pdcelec · 19 Oct 2005

It must be a large fan to have taken 18 months to fit it.

megawatt · 19 Oct 2005

I'm intrigued why you need any cooling at all if the room is adequately ventilated.

My home setup (3 W2003 servers and an XP client all on 3GHz Processors with 2 hard drives in each server) all sit in my office and require no cooling at all.

Ventilation is provided by airbrick and a half open small window

ban-all-sheds · 19 Oct 2005

Depends on the size of room.

And the equipment - the company I work for sells servers that put out 142,000 BTU/hr...

megawatt · 19 Oct 2005

BAS ... I (maybe wrongly) assumed that this was for a home installation and just wondered what equipment required this amount of cooling ... just nosey I guess

And, I suppose it could be a broom cupboard

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Extractor fan installation

Big_Spark

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