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Author Topic: Bitcoin mining room pressure  (Read 231 times)
OnyxQc
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December 30, 2017, 07:01:19 PM
 #1

Hi!

I'd like your opinions on our setup. This is our bitcoin mining room from an upside view. All of the Asic Miners in there each move about 230CFM when both fans are at max speed. We currently have 16 of these miners and project to get up to 40 at max capacity. The room is basically a 10 foot square concrete bunker but with an angled ceiling so i'm not sure exactly how much cubic foots of air is in there.

https://image.ibb.co/hrqnSG/mining_room.jpg

We've separated the room in two parts with an insulating aluminium wall in which we cut holes so that the heated air from the machines would go into the right part of the room. It is not completely insulated yet as we were afraid this would cause greater pressure problems that could make our miners fans work harder than supposed.

The air intakes on the left are two 2 inches aeration ducts with grills and no fans. In the hot part, we've first put a 1000 CFM 12inches industrial fan but it quickly became clear this wasn't enough as the hot air was getting pushed back into the first room trough every crack. We've then added another wide 30 inches by 12 inches air duct with a grill hoping it would be enough to evacuate the rest.

As of right now, we're doing fine with 16 miners but I still can feel a big amount of negative pressure when opening the door, it almost takes 2 hands to be able to open it.

I'd like your opinions on how we could make this setup better. There is a bit of a sound pollution concern when thinking about adding more outtakes fans since this is a residential neighborhood so there's that to take into consideration. Ideally, we would want the heated air to be evacuated while putting as less pressure as possible on our miners.

Thanks!
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MarkAz
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December 31, 2017, 01:47:08 AM
 #2

First off, I always install these first anywhere I'm doing mining, and I would recommend you do the same - super cheap and easy to install:

http://amzn.to/2BYcqAk

This will give you the ability to know if something you're doing is having an effect, beyond the door being difficult to open or close.  You might also want to pick up two of them, and have one be outside to cold side, and the other be the difference between cold side and hot side.  Then you'll not only be able to tell whether you're starving your intakes, but how balanced the two sides of the room are.

On your intake/exhaust, I'm going to assume those are round since you're giving a diameter, but you can easily use normal HVAC duct values to get an idea of what kind of CFM you're making available:

http://www.waptac.org/data/files/website_docs/training/standardized_curricula/curricula_resources/duct%20system%20sizes%20and%20airflow%20quick%20chart.pdf
or
http://buildingincalifornia.com/wp-content/uploads/2014/03/duct-sizing-chart.pdf

Your two inlets are probably giving you 1200 cfm - assuming 0.1 inch of pressure.   For your fan to be moving 1000 cfm at 12" means it's probably a little over 2x (non-linear) that static pressure.

You have a free-air opening which buys you basically 1800 cfm, but that's assuming there's nothing blocking it like a filter - if you have a filter on it, it will drop things considerably.

The first design issue with this that I can see, and sounds like you've experienced is short-circuiting airflow - meaning the fan is actually pulling air in from your free-air because of it's proximity.  Short of you creating some sort of wall between these, air is always going to travel the path of least resistance, and will get sucked in by the much higher pressure fan right next to it.

If possible, you'd probably be better off moving all the machines as close as possible to the vent, going to an HVAC place and getting a plenum made that takes all of the air from the back of the miners and funnels it directly into the 12x30 - this would eliminate hotspots and be more effective moving the air where it needs to go - out.  If possible I would add another 12x30, and plenum out to both of them.

On the sounds issue, the easiest thing to do to correct for that is just make sure the path for the air isn't straight.  When the fans are inline with the exhaust, you get the best airflow, but the best channel for the sound to travel.  You can also put louvers on your exhaust, and while it will cut some airflow, it will cut sound more.  Especially if you put another air gap and have louvers going the opposite direction.
OnyxQc
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January 01, 2018, 03:45:09 AM
 #3

Thanks a lot man, those are really great tips! I will make sure to order one of those manometers, this'll help balancing pressure. I'll do some research too about those plenum spaces you've mentioned, this looks exactly like what we need.

Happy New Year!
MarkAz
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January 02, 2018, 09:56:10 AM
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 #4

Thanks a lot man, those are really great tips! I will make sure to order one of those manometers, this'll help balancing pressure. I'll do some research too about those plenum spaces you've mentioned, this looks exactly like what we need.

My pleasure - this is a bit old, but you can see how I designed the plenum around these old A6's:



They all feed into an enclosed chamber which has extraction fans up at the top - the extractor fans I used were high enough static pressure that I didn't even run the fans on the Avalon's in this configuration.  The only real issue with this design was I underestimated how hot the plenum would get, and if doing it again I would have made it slightly larger and insulated inside, to help reduce some of the radiated heat that came from it.  We also had a warehouse setup with a bunch of these plenums, so once you get 20 or so of these columns pumping out heat, you can feel it even if it's venting the worst of it outside.

artinian_aua
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January 29, 2018, 11:00:19 AM
 #5

Hi there.

The layout you have on the image is a bit tricky. I'd suggest to use smoke in the rooms to understand your real airflows. You can borrow a fog machine or purchase one, it's really cheap. Try it out, it will help a lot. I believe you may end up adding an air dispenser in your cold room. 

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