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Hello folks,

I need some info/help on calculating how much BTU i need to cool down my GPU rigs.
Lets take the following example:
1 rig , pooling 1200W (6gpu) - take as constant. Is it right to say that after it's pooling 1200W it returns in air 1200W of heating ? I was struggling to understand this and following basic logic i think it's reasonable.
1 air conditioner, providing 10000 BTU/hr or 2.930710387 kW of cooling power. Does it mean that with this cooling power i can keep 2 rigs at desire temperature and the air conditioner would not run constantly which will make him die very soon. 2x1.2KW - 2.93kW = 0.53kW free.

Please help me to understand what cooling narrowed to BTU/hr i need for let's say 10 rigs x 1200W = 12kW

1200W power consumption = 1200W of heat added to the room in one way or another.
AC power ratings are a bit weird but pretty much what you've said. Its very hard to predict what temperature it will be able to hold but it would do what you're asking.

In bitcoin mining, you should avoid AC at all costs because it adds about 35% again to your power bill. The best solution is to exchange air to ambient, ie collecting and exhausting hot air to outside or open windows etc.

Totally agree about usage of AC but at the moment i can do it. What are you suggestions/setup/position of GPU rig to collect the hot air and remove it as fast as possible (like https://youtu.be/2rQ-YIDmsBc from Toom.IM) ?

That's designed for a much, much greater capacity but the idea is the same. Collect hot air with some form of ducting connected to an extractor fan. Look at dryer ducting for some ideas, order about a trillion meters of tape and see what you can come up with.

At a 12 SEER/CEER, your air conditioning unit will use appx. 28% of the power of yout TOTAL mining gear (not just the GPUs, but the entire computer) to dissipate the heat generated.


 I picked that figure as it's about the mininmum you can find for sale any more, at least in the US (I think it's a federal minimum efficiency standard or some such).

I didn't get that. Please elaborate.

The math is:
   BTU/hr=Watts x 3.4129
   1 Tonne=12,000 BTU/hr

So for 12kw load you are producing 40954.8 BTU/hr or 3.4129 Tonne of heat to be moved.

Thanks a lot for the info. This means that with AC with 32000 BTU/hr i will not be able to handle this if i don't find a way to "extract" the heat from the GPU and get a better advantage over this desired ~41k BTU, right ?

just so your following. he just did the math at 12kw --> 12,000 watts. not 1.2kw --> 1,200 watts.

yes i know that.... i have 2x12kw so it's relevant calculation. Now the point is how to remove some heat from the GPUs so i can use AC with 32k BTU i have in mind. Any suggestion for frame, gpu position and etc ?

You don't use AC, you slap a high CFM fan in a window, pulling all the air from inside to the outside. Even with free electricity, it would be silly to use AC, since you could instead use the available electricity to run more stuff.

I agree that blowing the heat outside along with a dedicated (and filtered) inlet from the outside is usually the best solution.

As for your situation, remember that normal AC unit ratings are based on keeping a room at a comfortable temp and having enough overhead for the AC unit to cycle on and off. If you allow the room to get up to say 85-90F (I do and my BTC miners are happy with it) use that as the temp setpoint and as long as you don't mind paying the electric bill for the AC compressor running non-stop then your 32kBTU system may be adequate especially in cooler climates/winter. Also, if you are working with a HVAC contractor on the cooling, mention the ability to have a higher air temp feeding the rigs. How high? That you have to test to find out what keeps rig temps at safe levels. That changes the cooling needed equation a lot.

Another thought. GPU's as in video cards from AMD/nVidia ect? If so look into liquid cooling, there are all sorts of commercial cooling blocks out there for them. Coupled with the right pumps and you can just stick the radiators & fans outside easy peasy with just a small dia hole in the wall for tubing & power to the fans. A helluva lot cheaper than using A/C.

I have run a 400 GPU farm with absolutely no A/C. If you need help, please contact me on skype (Kotarius). I can save you a lot of money.

does intake air volume must be 30% ~ 40% more than exhaust ?

Air intake and exhaust vent capacities should be designed to be equal, or very close to it.
If you are using fans on the intake, a HAIR higher on the intake side will tend to cause a slight amount of positive pressure in the room which keeps dust/pollen/etc. infiltration to a minimum from anything that isn't specifically designed to be a vent.

This is how most "old school" data centers were designed, and the "new school" stuff like the Yahoo "chicken coop" design is even MORE of a "positive pressure" design.

 Don't use fans for BOTH intake and exhaust though, that's a waste of power.
 Use fans on ONE side and size the venting for the other side to suit.

 The only reason to use both an intake AND an exhaust fan is if you are dealing with a high "backpressure" situation, an air path with a VERY congested airflow path - like the inside of an S7 or S9 miner.

I'm quite curious how this is done and what climate you're in that no AC is used.  I live in the Midwest, United States and in the summer, the ambient temp will far exceed what you want a room full of computers to be at.

I'm having my HVAC company come over next week to consult on adding a supplemental AC/system to only cool the server room(s).  If I can do this with mostly moving air and a little cooling (in the hot summer days), that'd be ideal.  If I had to choose between shutting down the farm on those hot days and paying for electricity to cool it, that's an easy choice.

The "pressure" aspect is interesting, I'll definitely do some additional reading on that. 

Good stuff guys.

Check what genesis mining have done and then you will learn how to do it properly.

Hey dogie

Long time no see :) or maybe i haven't been watching much into coins to much else were .....Ive been here but into this stuff more intense.
I Ignore a lot of the BS now.

I'm in southeast USA an in the summer, i use fans over AC other then maybe AC to keep the house cool and us in it . The fans run 24/7 or when ever i mine, i don't always mine 24/7 can't stand it but love it, if that makes sense . You have to move that hot Air and AC alone just won't cut it . it's misleading to think that AC will some how cool everything with out moving that cool air over something hot to cool it . TO me AC was invented mostly for health and comfort in the Summer times but led to other uses over time .. an AC still can't replace a good cheap fan for fast instant cooling when it's needed the must..

You can run your farm and still keep it cool with fans over AC an use AC to keep your self cool in the same house ... but the Power bill is still gonna go up even with just normal AC use and no farm running.
With the farm running full force and AC, it's actually won't be that much more in cost if you do it right .

 A properly designed mining rig can be quite comfortable at 90 F ambient, and most should be able to handle 100 if enough space is allowed between the GPUs for proper cooling.

 ASIC rigs vary - some handle higher temps well, some need to be downclocked.

 Even the big boys have started realizing this - reference the Yahoo "Chicken coop" data center design for a well-known example of a MODERN efficient data center that does not use traditional A/C at all.

Hello Gang,

I am interested in setting up some GPU mining rigs in the garage (the only spot with room). My issue is that I live in the deep Southwest desert. Temps in the summer here get up to 120F. So, I am not sure if just moving air from the outside through the garage will work. Any thoughts on how to set this up? I see a lot of talk about AC units not helping, but the outside temp would be scorching....

I really appreciate and help with this.

Thanks!

Nice info, Thanks.

I'm using 2 outlet fans on one side of the room and put filters on the next side windows to filter out dust.
Also I put some pushing fans between windows and rigs to blow air to rigs.
Temp near the window before rigs is around 5 °C and near outlet fans is around 25 °C, outside temp is around 0 °C.
GPU temps are around 60-70 now.

I'm curious what will happen in summer when outside temp reaches 30 °C
Outside and inside temp difference is now 20~30 °C, then in summer room temp gonna go as high as 60 °C and GPU temps gonna reach 80 ...

Does pushing more air to the room gonna lower temp, or I should find another solution for the summer?
What are my other solutions?

More air flow would probably help a lot.
You could use an evap cooler pulling air in from the outside, or less efficiently from the "hot" side of the room, blowing cooler air into the "cool" side.
If you had to, you could use an A/C unit to put SOME cold air into the intake air, just don't expect it to get the intake air WAY down on temp but it might help a little.

I already have a 24000 A/C in room (not in use for now), but dont know if it could help when we pull warm outside air to the room in the summer or not.

I was actually thinking about evap/water cooling air conditioners too, but doesn't high humidity cause problem to mining rigs?
I have some of those at home, they raise my home humidity from 30% in winter to +60% in the summer when they are in use.

Guys, I'm a mid size miner (i Have 250 rigs) I also own a HVAC company.  I have survived 3 years of Texas summers where ambient is 105.  The key and I can not stress this enough is ventilation.  The more the better.  Don't be stupid and add 1 box fan for 10 units on the window.  Buy a 3000 cfm or bigger unit.  Put it this way, I have 30 units in one location that is 130 square feet and air-flowing from attic and pumping out through window at a rate of 9000 cfm.  Its a vortex in there to battle the Texas heat.  Is cooling it better?  Absolutely but the cost incurred is great, plus it takes 50 amps of mining away.

Calculation is this.

say you have 10 machines doing 1200 watts
10 x 1200 = 12000 watts
12000 x 3.41 (btu per watt) = 40,920 BTU
40,920 / 12000 (12k btu per ton of air) = 3.41 Tons

So you will need 3.41 Tons of air to cool just the machines so in this case a 4 ton unit should be fine.

Hope that clears stuff up.

Thanks a lot for the info.
Gonna add more and more fans ;)

 I've never seen the output of my Evap coolers get *TO* 60% RH.
 Realistically though, electronic gear is normally specified to handle at least 80% and often 85-90% RH while operating - and given how HOT miners get internally, you could probably feed them ANY level of humidity at the input that doesn't have active condensation without issues.

 Then again, even WITH one evap in the mining area and a ultrasonic "small room humidifier" in the office area running right now, I'm only seeing 26% RH in my office area and 28% in the mining area, even though it has been intermittantly RAINING this morning.

Check Two Ton Hasher youtube channel

He lives in Florida (Can get very hot and humid during summer time/hurricane season)

https://www.youtube.com/watch?v=E-_9F8R_PFU

https://www.youtube.com/watch?v=_qbLkivgxps

effective extraction > cooling air temp.

If you have both = winning

If you have a free electricity you can do it, but keep in mind that many of AC's are burned down due too 24// working hours.
Something like central AC industrial standard is preferable.

dagarair:  Thanks for the post, good stuff.  I'm curious what your thoughts are on airflow for a home "server room" in the Midwest (Northern Illinois).  Based on my prelim calculations, I probably won't need AC ever (middle of summer is iffy) to cool the room however I'm designing it now and my main concern is a large enough exhaust.  Since I have to open up my exterior wall (twice, for intake/exhaust), I'm trying not to make holes bigger than the width of the studs.  The room will have dimensions of 4' by 13.5' (54 sq ft).  My hot aisle airflow isn't ideal however it's not terrible either.  It will be semi-sealed with only an exhaust fan and (industrial grade?) filters on the intake (don't want critters/dust/etc in my server room).  I also need to manage the sound since I live in a residential area and my neighbor is 15' from the edge of my house...  I'd considered looking into exhaust designs to minimize the sound so all my neighbors don't hear it all day...

Any suggestions on an exhaust fan (CFM rating)?  I'm not asking you to endorse a specific product however I'm not opposed to some suggestions either. 

I almost forgot, my current design for that room will be generating 90k btu/Hr.  I'm working on a secondary room design that'll generate another 120k btu/Hr of heat, same question there and would love a suggestion on exhaust fan capacity.

I realize this is subjective since what one might feel is an adequately cool room will differ but it gives me somewhere to start.

https://www.ebay.com/itm/QC-Manufacturing-Inc-QC-Manufacturing-Inc-AFG-PRO-3-0-QuietCool-3013-CFM-/253174861824?hash=item3af265d000

3000 cfm for an outstanding price.  All I use in home installs

Thanks, that's a good start.

I made some changes to the layout of the room and got very good results.
Open windows and puller fans were in cross walls and back of the rigs were on windows with pushing fans between rigs and windows,
I turned rigs 90° to the windows on the other side of the room facing the puller fans.
Now the air flow is direct, from windows to push fans to rigs to puller fans.

The result is amazing, outside temp is now 5° C and room temp is 10° C, while GPU temps are around 30-40° C.

So my suggestion to every one is to set your layout to have a direct air flow from outside to your rigs and then to pulling fans so the hot air won't circulate in room and directly gets out.

I am trying to calculate the required CFM (RCFM) for the area 10'x5'x6' with 7kW of power in it.
My calculations are:
V = 10x5x6 = 300 ft3.
BTU = 7000x3.41 = 23870
Air changes per hour (ACH) in data centers is suggested to be 50, so
RCFM = 300x50/60 = 250CFM

The problem here that 50 ACH I found in some guides "how to build a data center", so there was no really explanation where this number comes from.
I think ACH should be calculated somehow with using BTU.
And second of all 250CFM doesn't seem enough for 300 ft3 and 7kW.

Any advise if my calculations are correct and how to connect CFM with BTU please?
 

You divided by 60

What do you mean? This is how you get CFM (Cubic Feet per Minute). RCFM = Volume * ACH / 60.

I'm going for one of these when the outdoor temps start getting warmer here ...

https://www.amazon.com/AirKing-9166-Whole-House-Window/dp/B0007Q3RQ6

I know what is there on the market, that thing is 3000CFM, for sure it gonna blow like a hell, but again if you have a 1000 GPU it wont be enough.

So my questing is to how to calculate required CFM based on BTU/ACH.

Just curious i have about 22 rig each rig is doing about 600-700watt
22X700 =15400watt
15400 wattX 3.41 = 52514 BTU
53000BTU /24000(assume i buy aircon with 24kBTU) = so does that mean 2 such aircon is enough or maybe i add to 3 of such aircon?

I know alot will say is a waste but currently using ventilation cause alot of noise which i still think to run with aircon is it possible


yvmen

I have open my computer case and this great cooling.

Im not an expert by no means but couldnt you cool air in another room, have the mining room have a powerful extraction fan to vent the heat, then have cool air passively "sucked" into the hot room?