This rate is for 6000RPM fans?
Because I have experienced a lot of orders from alibaba of fake Delta/Nidec fans which can't surpass 4200RPM.

I don't know does the room size matter? I'm thinking about the air volume.


The thing is I made a small piece of manhole that's being held by silicon adhesive. I opened it few days ago and tried doing a similar test like what you asked (sorry didn't see it ahead of time).

The test was, I was holding a small piece of paper and tried bringing it near to the suction fans. And they were sucking the air but the movement of the paper was being a bit strange when I bring it to the edges of the fan. It was like a mixed movement of suction and discharge. It's like the exhaust fans does need to take from an outside air a bit of air to compensate the air they need to suck (I'm not sure about it).

But I definitely notice when I opened the manhole and the hot air returned to the cold room, the miners' fans sound/noise changed. Since the fans now has enough suction.

I'm thinking now to add one more swamp cooler. But I'm afraid that it won't be enough. But based on the calculations, the 2 swamp coolers should have been enough.

I thought about that too. That's why on my second farm I increased my intake air of the room. But I'm confused. The only thing about the computation that I'm not sure of, is the antminer s9 fan intake CFM. I based my calculations that an S9 14th/14.5th can intake 200CFM per unit ( I read that somewhere in the forum few months ago) but I think fans at 100% full speed draw a lot more than 200CFM.

Cuz in the second farm my intake air is around 12,000 CFM, and let's say 45pcs S9 intake at 200CFM each that's 45x200= 9000CFM there should be 3000CFM which won't be replaced in a minute (based on the equation).

If you have any idea about how much air does an S9 Fan at 100% full speed suck kindly guide me.

Hello dear community, I am new miner with 2 small farms now. First farm includes 45 antminer s9 (mixed) and 15 cheetah miner F1 20th.
This farm is divided into 2 parts (cool room and hot room).
Total room size is 7mx3m and a height of 2.5m. The cold and hot sides are separated by an mdf wood with the miners exhaust fan exiting to the hot side. The cool room side size is around 4x3m, has an evaporative cooler the one used in green houses with a size of 2m x 1m (this is my only suction of cool air).

This farm was my first ever built farm. With 30 Antminer s9 as starters everything was fine. When I added the rest, I faced a problem where the hot air exhausted to the hot area is going back to the cold area from the small holes where the miners exhaust fans are inserted.

I tried too many things, tried increasing my exhaust fans to a total of 13,000 cfm but no help. The other fans keeps slowing down their rpm. Tried putting the same fans to suck more air from the evaporative cooler but still some of the fans loose their speed because some of the suction is coming from the inside of the room. I somehow think that my suction opening is smaller than it should be. But I have no choice I can't increase the size of the suction wall (as of what I think).

The same thing happened to me with the second farm which has 45 antminer s9 in a total area of 5mx2.5mx2.4m height which this room was divided into 2 exact areas for the cold and hot room. With an inlet automatic coolers which can supply around 12,000 CFM of air with temperature between 28 to 35 degree Celsius With an exhaust fan of 8000 CFM and another 4200 CFM.

I really hope someone can guide me with what to do to improve these farms cuz a lot of the miners are being affected because of this returned hot air specially with the weather here reaching 45°C ambient temperature.
Or even how to calculate the correct room size /suction/exhaust/etc. For my other coming projects.

Thanks a lot.

I will include some pictures in the coming days to visualize more about the farm.

السلام عليكم، ممكن اعرف من وين اقدر اشتري اخ @mikeywith??

So I think assuming 270cfm would be a safe number.
Assuming I have this number, for 50 miners that would be 270 x 50 = 13,500cfm.
Assuming every miner burns 1450W, I saw an online calculator to calculate the W to BTU/hr which is 1W=3.412BTU/hr ( I don't know if this is correct.)
So 1450W x 50 x 3.412 = 247,370 btu/hr.
I don't know if this is correct or not.

But if anybody knows how to calculate to get rid of this heat please help me. In the summer the ambient temperature here reaches upto about 49 degree Celsius sometimes.

Do you happen to know how much is expelled by the antminer s9?

Can you share the calculation for the airflow of the room? I'm planning to do a familiar farm.
But mine will have some swamp coolers (since my area reaches outside ambient temperature of upto 48 deg Celsius in the summer).

You can pm me now.

Would definitely look into it. Thumbs up 👍.

I am looking to buy old miners like the S9 series of bitmain (except the K and SE) , Avalon miners Series 8 (821, 841, 851)/ Series 9 (any model), bitmain L3/L3+/L3++, innosilicon Sha256 miners

You can also contact me thru Telegram : @cryptostashman

Aren't they 11.5th @ 1200W?
Or these are another marketing numbers?

Where can I get a good deal of the 821s with bulk order?


This is a very helpful info. I really didn't know this, since I have been reading about old gears they seem all familiar with the 6-pin connectors.

This might be a small problem for me as the temperature in summer here reaches upto 47 degrees. Celsius. Yes you read it right. But I think I can compensate it by adding an AC if the swamp coolers don't do a good job (but I think they can do a pretty job) I got a friend which has a mixture of gear like s9, L3++, and some s19s. I would be doing the same cooling setup, but the thing is according to the datasheet of the avalons, their max temp is rated @40 degC, while the bitmains are mostly 40.


Do you mean like the array connection of the miners using the AUC3 cables, AUC3 converters, and the controller? Or are there more to it?

Noted.
I Lost a deal with the 852s.
Currently I have a deal with 821s but they're too old. But price per Tera is so cheap that makes me think of taking the deal, and whatever I save from the difference of my other deal with s9js would give me the chance to purchase the latter.


This is a very good information. Thank you a lot for this.
I think I accept the fact that Canaan is a better choice, and the good thing is it can save wiring Lan cable because of the array style it's using.

My only problem now is to look for another offer from the suppliers since the 852s might not be the choice now. I'm thinking since I have a very cheap rate and a good supply of power I can still mix my farm between 821s 841s and s9js if I can get my hand on a very cheap 821s.

Yesterday I had a deal for 821s @85 CAD.

My list is open since what I care is reliability + cost/Tera.
I might be open to whatsminers too.

Thank you for the information.

Well, if I'm to choose from A841, A851, and A852.
Which one should I get?

Specially I can't find deep information about the A852.


But if I found some cheap ones which has less $/TH price.  Would I buy them? Let's say I found A852 for $200 that's around 13.33$ per TH, and I found A921 for $240 which will be valued @ $12/TH.
Is it worth it to save more with the A921 and deal with the maintenance or no?

Actually we did the calculations, and since rental is not a problem since my partner is the owner of the place.

And we are accepting the fact that bitcoin might dip in the near future. And we found out that our investment can have a 3 to 4 months roi. Since when btc dips usually the difficulty will drop. And we are planning for a long term holding btc.

So my question now is which is the better option of hardware that is reliable enough with less maintenance and problems.

I'm sorry I corrected my post.

It was a mistake while converting my currency to usd.

It's 2.5cents per kwh

Hello all.
I am totally new to Asic mining, I used to mine on a gpu rig at home 3 years ago, but never had the attention to use Asic miners because of their high prices and unavailability in my country.

Currently I received an offer from a friend to start an asic mining farm since he have an access to very cheap energy (around 25 cents per Kw)
 of upto 250KW.

So efficiency is not a problem here.

I found out that old Asic miners a lot cheaper these days than before, but I'm struggling to choose from a lot of manufacturers like bitmain, Canaan, innosilicon, Aisen, etc.

Doing some research I found out that maybe Canaan has a good review of users, but bitmain is more easier.

Anyway, my targets are old S9's, Avalon 841, 851, 852, Aisen A1, innosilicon T1, T2, etc.

Those which are cheap ASICS.

I wanna know which asic should I go with?

My target is cheaper cost with higher TH and reliable equipment.

Minimum 10TH to 40TH.


I hope I can find the help here.

If anyone has a reliable seller too I will be glad to contact them.

Thanks alot.