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Old 07-30-2009, 10:14 PM   #1
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How much power does a small furnace blower use?


When I build my server room I'm thinking of setting up where in my rack all the heat goes up, then gets sucked into a duct (would probably use a combination of ducting and dryer hose) and I'd use a blower to blow it away from the server room about 40 feet or so to an area I want to heat.

This would solve two things, 1: cool the servers off rather fast, 2: use the generated heat efficiently to potentially slightly save on heating costs. Now I'm just wondering what type of power usage I'm looking at for a blower? Probably does not need to be a furnace blower per say, but one that can move quite a lot of air in a dryer hose, and not do too much noise. A washroom fan blower is way too loud, while a furnace blower is rather quiet.

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Old 07-31-2009, 06:19 AM   #2
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How much power does a small furnace blower use?


Unless your forcing air to move through the rack. Your servers won't stay cool.

You'll need bigger then a 4" hose to move enough air.

How big, depends on server wattage, and incoming air temp.

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Old 07-31-2009, 09:18 AM   #3
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How much power does a small furnace blower use?


Yeah will be forcing air to move through. Basically cold air from the crawlspace will come in from the front, then the hot air will be sucked from the top/back. Idealy I'd want to seal off the cold air from just going straight to the top, and make sure it goes through the servers first. There will only be like maybe 5 servers, so it's not a huge data center or anything.

Also wondering if I should use something bigger then dryer hose. What is a standard size for a blower? In fact, where would I even buy one? Was doing research and did not find much. I can always rig something up with a high powered fan, but a blower is probably more efficiant.
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Old 07-31-2009, 09:55 AM   #4
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How much power does a small furnace blower use?


For each 3kw dissipated you need to get rid of up to 10,000 BTU/hr.
Fan noise depends on impeller design.
And just like a heat sink with forced air cooling you should guesstimate the thermal resistance (in C/w) of the servers.
http://en.wikipedia.org/wiki/Thermal...in_electronics
http://www.engineeringtoolbox.com/ov...ent-d_434.html

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Old 07-31-2009, 03:18 PM   #5
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How much power does a small furnace blower use?


You need to know the max air temp you will get from yoour crawlspace.
Which will vary withe the temp ofthe air that is drawn into it as the fan runs.
Then you can determine the CFM you need, and the fan/blower size, and the size of the pipe.
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Old 07-31-2009, 07:31 PM   #6
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How much power does a small furnace blower use?


Yeah not looking for anything super accurate, just some powerful enough air flow to bring the heat out. If it gets to a point where the cool air from the crawlspace does not cut it I'll put an AC unit in.

But now that I look I'm not finding where I would even buy blowers, found a few sites but they did not have much detail. Anyone know of a good site to buy that kind of stuff? Just a site that specifies basics like power usage/source voltage, CFM, diameter would be good. Using an actual furnace blower is probably overkill, but something with like half the power would work.
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Old 07-31-2009, 09:29 PM   #7
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How much power does a small furnace blower use?


Based on research typical blowers produce 100's of CFM of air movement, but some computer fans can also move this much, is this right? I would expect to have a HUGE difference. Is it that computer fans move it but are not as strong and more affected by static pressure?

Think I could get away with just building an array of 9 or even just 4 120mm fans? Or would that be too weak to push air through a duct or dryer hose at a decent distance? Also what type of blades are "stronger" to deal with static pressure, should I look for anything specific, like turbine fans vs standard blades? Are blowers designed the way they are specifically to combat high static pressure?

I'm looking at these specifically:

http://www.ncix.com/products/index.p...ufacture=DELTA

Probably 4 of them would do, I think.

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Old 07-31-2009, 09:40 PM   #8
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How much power does a small furnace blower use?


Go to FanTech.

Those 120mm won't move enough air throubh a duct/ You'll need alot more then 100CFM.
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Old 07-31-2009, 09:47 PM   #9
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How much power does a small furnace blower use?


If you can get cooling data using a box fan in a temporary setup the results can be scaled up.
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Old 07-31-2009, 09:59 PM   #10
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How much power does a small furnace blower use?


At this point I'm more concerned about overall air flow right now with only a few servers I don't produce enough heat for it to be an issue. If I need more cold air I'll probably get an AC unit or something.

I want to ensure that whatever I do actually moves a decent amount of air, and not use too much power as it would run 24/7. Basically enough air so that if the tube spans like 50 feet with some curves and what not, I can feel air coming out at the other end. So would those 120mm not do? What I'm thinking is something like this:

I'd use the 150cfm fans though I am fond of the 250cfm ones. My server room sure would sound like one. :o I'll have to insulate it for sure.
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Old 07-31-2009, 10:03 PM   #11
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How much power does a small furnace blower use?


"most should rise to the top"
http://www.engineeringtoolbox.com/co...fer-d_430.html
You could run a convection experiment without any fans.

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