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Exhaust fans for network closet

Linwood

Active Member
BraveSirRobbin said:
Is my suggestion of obtaining louvered doors out of the question?  I really believe this will solve your issue.
 
Louvered doors look really good, especially if left in natural wood and not painted (but you will want to match your other doors of course).
You mean the whole front?  
 
Had not thought if it that way, I thought you meant a louvered opening like a vent.
 
I have seen those before, that's an interesting thought.  I think I will still try first the simple thing of either double fans or stronger, but that's an option that did not sink in the first time, thank  you.
 

Linwood

Active Member
So if anyone is foolish enough to follow this process....
 
I decided to experiment hooking too more fans back to front with the existing ones, because they were cheap and silent.
 
Bad idea.  Really bad idea.
 
On the good side just a rough feel of air flow it worked nicely, the air flow was substantially increased, maybe not double but just by "feel" about that.
 
On the bad side it is VERY loud. Put close together there is some kind of resonance (or maybe almost resonance) that creates a loud hum.  These fans were almost inaudible before, at least at any difference, now the combination could be heard 20-30' away.
 
So I tried separating them by the width of the wall.  That made a lot of difference, the really loud noise only came when they were back to front, but at about 4" distance it was much quieter.  But still too loud.
 
So I tore that apart.  I also did a bit of experimenting with a digital thermometer I had previously compared with the zwave thermometer in the closet (about .75 degrees off, varying a bit).   The zwave device is at the hottest part of the closet, most of the closet hangs about 2-3 degrees above ambient.  The zwave device is purposely at the hottest point, so that is good, but the real point is I think I was fixing the wrong problem, there appears to be adequate airflow to cool the closet overall, but stale air at the top away from the new exhaust. 
 
So incarnation #2: I took those two extra fans and put them under a wire shelf about 2' below that corner, blowing up.  My hope is that it circulates the relatively cooler air to that corner, and across the top to the exhaust, better equalizing the temp in the closet.  A better alternative would be another exhaust on the other side of the closet, but neither side nor back is really suitable for that.
 
So now to let it run a couple days and see how well that works.
 
Getting both quiet and cool airflow in a closet with a PC is not straightforward.   :angry2:
 

wkearney99

Senior Member
Linwood said:
Getting both quiet and cool airflow in a closet with a PC is not straightforward.   :angry2:
Agreed.  It's been a very long time since I've dealt with airflow/cooling issues but the memories of the hassles live on. 
 
It's possible, for example, to set things up such that you end up with vortices and/or eddying currents of air.  Where moving air faster leads to starvation of heat removing air.  As in, accidentally creating dead spots that cause overheating.  So more/faster is not always better.

A thermal camera helps quite a bit, letting you literally see the overall heat picture.  Seek Thermal makes some nice entry-level ones that plug into a phone.  Using an IR thermometer (the laser dot kind) is a LOT more tedious, but still better than just monitoring an arbitrary point somewhere in the box.  That's what you end up with once you find the right place to monitor.  Finding THAT spot is tricky.   I generally go by monitoring the most expensive stuff first, followed by the known heat-producers.  Make sure the spendy stuff isn't getting cooked and that the heat-makers are getting enough air exchange to run optimally (without baking everything else near/above them).
 
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