Topic: 30kW mining farm - need ventilation advice [Reward] (Read 1129 times)

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Mike Miller
Factory Fans Direct
Bitcoin Ventilation Experts

Hey dude

Here are a couple of pics of the setup I just dismantled.

https://image.prntscr.com/image/cJvV7iT4Td6tbmi6utrY7w.png

https://image.prntscr.com/image/fNlFoqNESCOfMLBqjvvbdw.png


It may or may not help you.


I didnt do any calcs for cooling as I had certain restrictions

The 400mm fan is only 400mm because of the studwork.

The 600mm fan was the biggest I could get in the window.

I will send some pics of my new build when i start if that helps.


Im having a raised floor with intake coming up through the floor in vents, and then ceiling fans taking hot air out.

What room temperatures do you have on your farms? We currently run about 200 GPU's in 10-12C and GPU's keep runing on 30C @ 70% Fans... (large space, venting shut off)

So what you're saying is a really big AC can solve global warming...

Say what? An A/C unit IS A DEHUMIDIFIER.  Thats how an a/c unit removes heat.  It is the humidity in the air that carries the heat.  The humid air contacts the cold evaporator and the heat is drawn into the refrigerant within the evaporator. The water falls to a catch pan and is drained away from the unit.  The refrigerant takes the heat out to the condenser coil outside and it is then rejected to the atmosphere.  Then the cycle starts all over.  (This is the super simplified version without getting into pressures, compressor, metering and fans.

Agreed. I'm running roughly the same but using a single exhaust fan with a max of 3560 CFM. http://www.airkinglimited.com/page/window-fan.html

It's doing a great job so far. Will prob have to add a second soon as I add more miners.
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Wow thats really low. I am guessing it is because u have 10 degrees outside. Mine is 25-32, no seasons, juz permanently that temp.

I am using 18kw out if my 20kw at the moment. Also my layout is such that I point the machine hot air at the exhaust fan . I believe that helps. There is a good amount of space behind the miner for thr hot air to occupy but the airflow is strong and it gets sucked out quickly anyways. Since u have almost twice as much watts, maybe 11000cmh could be enough. I believe it depends on layout too. More is better and safer I guess. Also, good air pressure is important to pull the air into the ducts.

The bigger issue is how mining difficulty is going up too fast these days though sigh.

10k CFM seems pretty overkill to me. Im running a single exhaust fan: https://www.amazon.com/gp/product/B002TXL5P0/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

1.6k CFM for ~ 15kw worth of miners. Temps are about 10 degrees above outside.
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Agreed. I'm running roughly the same but using a single exhaust fan with a max of 3560 CFM. http://www.airkinglimited.com/page/window-fan.html

It's doing a great job so far. Will prob have to add a second soon as I add more miners.

10k CFM seems pretty overkill to me. Im running a single exhaust fan: https://www.amazon.com/gp/product/B002TXL5P0/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

1.6k CFM for ~ 15kw worth of miners. Temps are about 10 degrees above outside.

@brokenarrow

I’m going to the farm to knock it down tomorrow as the landlord doesn’t like the noise.  

It’s like 96dB or something stupid. May have made that number up...  

So I will get some pics before it all goes.

I’m running about 28kW.

I’m thinking to move it to a lead lined container I have access to.

The warehouse is huge, so I didn’t have any issues with re-circ on the heat.

Industrial Ventilation Extractor Metal Axial Exhaust Commercial Air Blower Fan https://rover.ebay.com/rover/0/0/0mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F40138896289

Also...

I had a quote for custom ventilation to be made for same size room
2 x intake & ducting
5 x exhaust fans (5 was recommended number)
And cowling and muffler / silencer
Around £1000

@crazydane: Looks good, can't figure out why the fan I got quoted was almost 10 times more expensive...

In my case I probably need a ceiling fan, which apparently is a bit more expensive, but not that much..

Whoa, your fan is 10500 CFM, which is 17800 CMH (M3/H). Just take note of the difference in case anyone stating CMH instead.
You can double check with the formula I wrote, with inside/outside temp but note it's for m3/h.

I'm not sure, but your fan seems to have 1/2 hp, if i use an online calculator, that is 0.3kW. "My" fan was 3kW, so it might be 10 times stronger, but I don't know how it's calculated. I guess more power is important with longer ducts and filters.

Let me know what you figure out!

I'm looking at a similar heat load.  Been looking at these 10,500 CFM fans for around $400:

https://www.northerntool.com/shop/tools/product_200422375_200422375

200 CFM per 1,500 watt miner means I could do about 50 GPU rigs or ASIC's with one of those fans, as long as I have unrestricted airflow.  So even if I loose 50% to intake filters and what not, that still leaves 5,000 CFM of air flow.  5,000 / 200 x 1,500 = 37,500 watts my miners can put out.

The fan above uses 3.5A at 230V, so that is about 800 watts.  That's about 13 CFM per watt, so quite efficient.

Any negatives to using fans such as the above?

Spec sheet:

https://www.jdmfg.com/wall-master-exhaust-fan

@polymer_city: How many Watts do you have in that room? Cheap fans sounds nice, as long as they are built to run 24/7, but how do you get the air out of the building, do you have any ducts? Yeah a picture would help if you can arrange it. If you have any ebay links and/or specs of the fans it's interesting.

@Sandal_hat: Yeah, 18000 cmh is really huge, and I guess I agree with you about overkill control setup. Just a knob to adjust it to see what happens would be fine, but maybe some electricity can be saved by not pulling more air than necessary. The fan is rated 3kW on max, but if 6-7000 would be enough I guess it'll be cheaper, and even cheaper in the winter.

@griffoincoin: sorry, not in UK. How is the data centre cooled, I guess a data center full of miners is much more hot than regular web servers and such...

If you are in UK then I can offer you a rack in datacentre. I also keep all my stuff there.

I see but isnt it better to just put the intake fan to exhaust?

it is better to also use intake ones to reduce load on exhaust fans

At first, I wanted alot of fan power (based on wat I read on the net and some calculations) but the engineer recommended me about 5000 cmh and I end up putting about 5500 CMH only. I can control the fan speed via a controller but I just leave it on near full power. I only lower the fan for a couple of seconds when I change air filter paper. If I buy an additional slide-in panel for the filter, I can probably change it by juz changing the whole panels and not the filter paper. I wouldnt need the fan speed controller then lol and can juz leave it at full power. I dont use any sensors, juz a simple fan speed controller, something like this http://img.directindustry.com/images_di/photo-mg/5369-9723484.jpg  . I skip using those expensive variable speed drives....dont need it lol.
 
My area is about 24-32 degrees and weirdly, I can get around 30 degrees inside when outside is 32 degrees but this is on the cold side of the miners. I never measured the hot side as the air is bound to be hot. More importantly, there is only 1 row of shelves and all the hot air goes into a sort of collection area and is immediately thrown out by the fan.


I wonder if 18,000 cmh is overkill. Anyways, more airflow cant be wrong. Bare in mind, 18,000cmh is huge, and so if any water gets pulled in the intake duct, it is going to pull the water quite alot in the direction of air flow. Also, the exhaust fan may push the air outside quite strongly for a few meters. Do note, u dont want trees receiving that warm exhaust air as they will probably die. U should check how far forward the air will be pushed out and if that will affect other stuff. Also, make sure the exhaust hot air cannot come back in if the wind changes direction. For my setup, the middle to bottom portion of the room has little more airflow and thus, is abit cooler to put all my miners there, rather than on top portion.

Your antminers will be far louder than your fans. There are far cheaper fans on amazon also. I used an expensive box fan due to the need to fix it with ducting, a fan speed controller and I also rig it to off the distribution box if it were to malfunction.

How many CMH of fans is the exhaust fan? By right, if u push air outside, air will automatically come in, u dont need an intake fan.
The centre fan helps cool the miners? What temps u have outside and wat are your antminer temps?

For my setup, the middle to bottom area has more air flow and is abit cooler to put machines there then right at the top. So, I place all my asics there lol

I have 27 D3’s and 1 x S9in a tiny room in a warehouse.

I had huge issues with cooling to start.

I resolved this pretty easily.

400 mm intake fan into cold isle at low level

A 600 mm mobile fan in centre of cold isle facing upwards

600mm exhaust fan in centre of wall on hot isle.

The fans were from eBay around £250-£400 each.

I have control software which then lowers / raises frequency according to antminer temperature.

The 600mm fan is probably only slightly quieter than the 28 antminers that are running!

I’ll get a pic up if it will help

@Sandal_hat, thank you very much for the very detailed answer.

SHELVES:
These mining rig cases will be used (Veddha 8GPU Mining rig case: https://i.ebayimg.com/images/g/QpcAAOSws1ZZs276/s-l300.jpg), they can be stacked, and no shelves are needed. The downside is that you have to take all off, if you need to remove and service the bottom one. Is there any other advantage for using shelves? Perhaps higher distance between each rig, and the shelf between, so air doesn't go up to the above rig?

FAN:
On the image above, the fan is misplaced, the idea was to have it centered in the room. I guess two fans would be good for backup, but it's probably much more expensive, since each will have it's controller etc, but of course, no fan running at all with no mining would be very costful too.

How much air volume is your fan moving, and what is the average temperature inside your mining room, and outside?

I got a recommendation from a ventilation guy using this formula:

V = 3P/T2-T1.
 
V = Air volume (m3/h)
P = Power consumption to exhaust (W)
T1= Outside temp (ºC)
T2= Max temperature in mining room  (ºC)

In an example during summer, where it can be 25ºC, and I want the room to be 30ºC or less:
3x30000/30-25 = 18000 m3/h.

With a pressure drop due to ducts 250Pa he recommended a fan with these specs:
Air flow: 31500 m3/h
Max pressure: 600 Pa
Weight: 94 kg
Sound: 74-77 dB (yeah I guess that's pretty loud?)
Consumption: 3kW
Fan diameter: 1020 mm
RPM: 1450

How does that sound? It sounds HUUGE to me.. Price for that is about 4500 USD if i try to convert it. Plus controller, sensors, accessorier.
The weird thing is that I find lots of fans on Alibaba for $200-300. How can it be so much cheaper? I don't have to ship it, but it's still 4-5 weeks shipping.

I'd rather make it bigger than it needs to be, and be done with it, than change it in a year.

Great idea about the vents directed away from the machines.

Thanks again!

I did mine with around 20kw. I am not sure what i am looking at exactly in your drawing.

I hope u realize that the sound will be VERY LOUD. U can hear it even 15-20 meters away.


Tips:
Shelves - use good shelves shelves that can take over 100kg, not those ikea shelves with 32-40kg max load weight.
Your air intake and exhaust - MAKE SURE the exhaust HOT air does not recirculate into the AIR INTAKE in any situation. Meaning the hot air that goes out does not get to back into the intake if the wind blows a certain way. Account for the fact that wind changes and put a good margin of safety on this.

Airflow - U dont need air intake. As long as the room is sealed and air is pushed outside the room, air will automatically enter the room through any opening. The amount it pushes air out depends on the pascal air pressure in the room. Mine is around 200 pascal via box fan, something like page 280 here http://rosenberg.com.sg/wp-content/uploads/2015/04/worldoffans_en-2.pdf . U can use any sort of fan though. In general, dont take air in from ground as the air is abit more dusty and since warm air rises, it is abit better to put air out-take/exhaust fan at higher point or at least middle.
Also six 0.1m2 holes is about 0.6m2 total. That may be too much. Your air pressure pascal might be too low. U may wanna get an engineer to calculate or perhaps start with smaller holes and widen them slowly.

Air dust filter - This is important but do note that it will slow down the air flow coming in a little depending on wat air filter type u put, be it G3/G4/etc filter.

Rain and air intake area - This is important. Since u have ALOT of airflow going in and out of your small room, u gotta make sure the air intake does not pull in water as well. I suggest having the direction of air coming in not point directly at your miners as it may bring some water in. For example, the intake air comes in through a duct that face downward to the ground, making the air come in facing downwards. This way, if any water droplets gets pulled in, it will drop to the floor. I suggest leave some distance between air intake and shelves. Same with exhaust, u may need to push the air through a fan through a duct due to rain, depends on situation.

If u have the space and it is economical enough, u may want to split it into 3-4 exhaust fans rather than 2, so that if one fails, u still have 2-3 working. Alternatively, u may wanna try get an electrician to use control circuitry with your box fans (if your box fan has that function), to wire it to the distribution box such that if the box fan fails, it shuts off the power at distribution box. This is because if box fan fails, your machines will overheat and the miner goes into overheat protection mode which works fine but I juz rather avoid. However, not all electricians know how to do this, juz fyi. May cost abit also.


Electrical -
Best to use power factor of 0.8 - 0.85.
Since it is on 24/7, this is continuous load, do not put more than 80% load on a breaker. Meaning if it is 20amp breaker, put at most 16 amp on it. Same with each socket, best to put more sockets and dont overload.
Make sure your wires are all good copper wires that are big enough. U dont want them overheating.
Use good mcb like hager or MK. Dont use cheap china mcb which may cause issues.
I use a surge arrestor for the distribution box to prevent surges. U may want one.