Heat is the amount of heat produced, also known as the load. It is equal to the amount of power consumed by the miners.


Heat Rejection means to reject the heat to the atmosphere. It's the capacity of the system. The system moves heat from indoors to outdoors.

12000 BTU = 1 Ton
1 Ton = 3.51kW

I don't know if you can ever get to quiet. If that's necessary you should reconsider this location or completely change how air is forced through the miners.

You can never be too thin, too rich or have too much airflow. More is better, but there will be diminishing value once airflow exceeds specifications.

Adding a fan adds noise.

If restriction is insignificant, you should not need a booster fan. I did see some folks on this board who tried a 4" duct which resulted in a very hot miner.

I think folks are too hung up on the flange. I just used duct tape.

This is a fun engineering exercise. Just try something, then restudy the physics to make smart adjustments to the design.

Sound energy, like all energy, is transmitted equally in all directions. It's good to absorb this sound energy with a material that is not good at conducting sound waves. Poor heat conductors may not be poor sound conductors. Air is a perfect example of this a very poor heat conductor but excellent sound conductor.

Basically, you need to find a way to absorb sound in every direction from the miner with very little airflow restriction in and out.

Those insulated flexi ducts are surely handy for that. My first attempt was a muffler constructed with cardboard boxes with egg cartons inside. Now days I do whole room systems so these single miner boxes are not something I mess with now. But the same rules apply.

A more ambitious approach could be to replace the fans with a fan designed to be quiet. I gave some thought to using a large squirrel cage type fan that's really a bit overrated for the miner. I'd just directly couple it to the miner input to the blower output. Radial fans like these used on the miners are only okay if you don't care about the noise.

I'd love to hear about what you come up with and how well it works. 

Thanks so much. This may solve my problem by setting to 0%. Hopefully, the missing fans will not cause an alarm if set to zero.

i'm not familiar with winscp and it's been decades since I used putty. I'll try to muddle through.

I'm developing a liquid cooled S9. I need a way to unplug the fans as they are not needed and I don't want to power them. Any suggestions welcome.

Sorry I'm late to the party here.

Powering the fans will not dehumidify.

A simple and cheap answer to me is to install a battery powered dew point sensor which closes a relay at <5F difference. Use that relay to start a diesel/kerosene, forced fan heater to raise room temp. Don't forget to exhaust combustion gasses.  I'd have the heater shut down at >10F. This system will prevent condensation in the environment all the time.

Telegram, so they can try to hide later.

The larger the pipe diameter the less airflow restriction. A very common error that causes premature failure is not accounting for this restriction If there is a restriction on the intake air supply, there will be a reduction of pressure which will result in less heat transfer to the air. So, same volume of air at a lower pressure can cause some ASICs to run hotter. There is a similar problem on the output except the increased backpressure will reduce the airflow. If you restrict both sides, the flow and pressure are both reduced.

The area of the circle changes by a squared proportion. Recall, Pi x RadiusSquared = area of a circle.
4" duct = 3.14x2"x2 = 12.28 sqin
6" duct = 3.14x3"x3 = 28.26 sqin
8" duct = 3.14x4"x4 = 50.24 sqin

So where 8" duct is 2x the diameter, it is 4X the area.

Airflow resistance is directly proportional to the length of the duct. So, if you double the length of the duct, you double the resistance. This also means you can run 4X the length of duct by doubling the diameter.

It does sound like you need to sacrifice a cooler. I'd probably just get one of those Styrofoam units, cheap and quick to cut, very good insulator.

If you do what you saw on youtube, I expect you'll get a similar result. I saw one or two there; I do think their duct looked too small.

100k BTU is not enough to keep 40 ASICs cool.

54kW heat, 29kW heat rejection.

4-inch duct is a very bad idea. There is just too much friction restricting the airflow.

Airflow is good, sound is bad.

The good news is that sound travels through air equally in all directions. I just wrap my miner in standard insulation, tie a 6" insulated flexi duct to each fan. I use a long enough piece to make one 360 degree loop so the airflow is the original direction but that's not necessary at all. I don't add any fans as the 6" duct is not very restrictive. If the duct needs to be longer than 4' I'd go with 8", especially on the suction side. 

Too many coolers have given their lives for this cause. A spool of R30 is cheap and right there when you buy the duct. 

 

I don't know what others are doing but I put in a buy limit order at 8500. If that fills, I'll put another in lower.

If a year ago you put 10% of your paycheck into bitcoin you'd be in great shape. You'd also be happy to see substantial pullbacks because your 10% paycheck would be buying more bitcoin.

Market timing can be good luck, can be bad luck. Dollar cost averaging puts the odds in your favor. It puts you in good position to benefit from those overreacting to volatility. I passes a fellow in the hall today who felt compelled to "inform" me BTC price plunged. I said yes I know, I'm buying 40% more this week. That math's not spot on but you get the idea. He raised both eyebrows fully up.

I started structured purchases in March 17. It was the best investment I've ever made.

I've been slowly buying miners. I hope that works out well too. That jury is still in deliberation.

Balls on these guys. Damn.

So their first try at designing a more efficient ASIC, BAM better than Bitmain and all others.
One day after Bitmain offers A3 for sale, BAM they do it better.

Just send us plenty of BTC.

Hmmm. not sure. The "ideal" rate is just a math function with the "RT" result is measured. If the RT is very near the ideal then all is working well.

As an example I have an old and new board in one miner with auto freq.

Freq.     GH/s(ideal)  GH/s(RT)
550.00   3950.10      3974.35
666.28   4785.26      4709.43   

The auto freq board sets the older board at 550 by default. It does not try to optimize the clock speed on this older board. I used to run this board at 625 on the older firmware.

When you increase clock speed you should see a proportional increase in ideal hash rate. If the RT rate is far from the ideal rate you can see the clock rate is causing some problems.

I'm not sure the clock setting on the new firmware sets the minimum clock speed as it says the starting clock speed. The firmware may reduce the clock speed from this starting point to find the optimum freq. I'm thinking this setting may get the miner started sooner upon restart if I program a starting freq very near the found optimum frequency. I may give it a try on one of the miners with 3 new boards in it.

There goes the 50th red flag.

OMG I really hope nobody gets ripped off on this. That would suck.

http://192.168.x.x/cgi-bin/minerAdvanced.cgi (change ip address to your miner's actual address)

There's the direct call to the Advanced tab. That's really cool as you don't have to use old firmware.

I went there and it offers the starting clock scan frequency as the only menu item. Mine was set at 550MHz but my hash boards are running at 665. I guess it started at 550 then worked up  to 665. Each hash board looks to be independently controlled. I have one much older hash board in this miner which is running at 550 while the new boards are at 665.xx

When I selected 575 as the starting clock speed and hit Save,  a warning popped up saying;
It will take about 3 hours on search frequency before mining! Are you sure?

hmmm. I'll set a miner up with a single hash board to play with.

So?
What happened???

I do have a few suggestions.

First, only use one hash board. Maybe even use a has board with one or two ASIC strings dead. So one that's barely working so there's much less at risk.

Install old firmware to get control of the clock.

Reduce intake air to <15C. Every 10C temp reduction should double lifespan.

Start at 600M and increment clock the smallest increments possible with 1 hour run at each setting. Document all parameters. Continue to increase clock rate until excessive HW failures, >1000 within the hour occur, or ASIC strings dies, whichever comes first. 

Report findings here to give others an opportunity to learn from the data and create a new tactic. Build knowledge base to allow aggressive miner types to maximize benefit.

 

†Allowable ampacities shown are for general use as specified by the National Electrical Code,
2005 Edition, section 310.15 unless the equipment is marked for use at higher
temperatures the conductor ampacity shall be limited to the following:
60°C - When terminated to equipment for circuits rated 100 amperes or less or marked for
size 14 through 1 AWG conductors. MTW wet locations or when exposed to oil or coolant.
75°C - When terminated to equipment for circuits rated over 100 amperes or marked for
conductors larger than size 1 AWG. THWN-2 when exposed to oil or coolant. MTW dry locations.
90°C - THHN dry locations. THWN-2 wet or dry locations. For ampacity derating purposes.

So now you know what is legal in the NEC.

If your wiring is rated as THHN or THWN-2 if wet, then you can use the 90C ampacity chart.

And yes, wiring not THHN rated is available.

That's why I worded it the way I did. I said to switch the battery to supply the miners when utility power is disconnected. Therefore the 13.8V charger will never be connected to the miner while it is powered. The battery would be on discharge which would be within specs.

13.8V is the correct charging voltage for lead-acid batteries, which are the best bang for the buck choice. There are many other batteries but they'll cost you more. Buying anything for mining that exceed 3 year lifespan is probably not the best idea as everything could be obsolete by then.

I didn't submit a comprehensive design with bill of materials and cost justification model because nobody gave me a PO to engineer this project.

I also didn't see an engineering design for the grossly impracticable water storage or cost justification PV model ideas. I'd love to see them because the ideas only gave me a mild chuckle. A submitted design would be worth sharing for us all to LOL.

Thing is, miners run on 12VDC. A UPS for miners is really simple as it is only a charger, battery and a relay. Crazy cheap, demonstrated millions of times as effective, easy to design with 100% certainty of performance effectiveness. My suggestion to the OP would actually work, and be cheaper than any other option that is within his original ask.

Be careful here. I would not use a 4in hose as the air flow resistance will be too high. It works just like a pipe where the larger pipe resist the fluid less. Same with wire carrying current. The idea you want is to allow full air flow but to absorb the noise at the same time. The sound will impact the insulation in turns but the air will flow around the turn easily. The sound wave is moving much faster than the air is. The larger the area for the air to move through the less restrictive it'll be. The more turns the sound has to make, the quieter it'll be. I prefer a 6 inch to reduce back pressure. I prefer 360 degrees of turns but 270 will generally do it if you need to direct the hot air a certain direction. The longer you make the hose, the larger the diameter must be to allow full flow.

It would be good to have. You never know when someone's network will fail. I don't like to miss a day or even an hour.