Hardware How-To

So you want to mine cryptocurrency in the guest room? Here’s what you need to know

I’ve talked to a few people (and read about more folks) that want to mine cryptocurrency in their spare bedroom.  Since the same questions come up every time I figure I would share some of my experience.

“Can I mine in my spare room/basement?”

The answer is technically yes but the devil is in the details.  Most people don’t realize the power requirements or the cooling needs.  Never mind the noise.  If you’ve got the cash and spare room, though, let’s figure out what it would take mine crypto in your bedroom.

More power

Just like Kirk from Star Trek, if you are planning on using more than one machine you will likely need more power.  For this article we are going to use Antminer S9s from Bitmain as an example.  You can learn more about the S9 on our ASIC page. The S9 is pretty standard model of ASIC miners.  It’s comes in a “tube” configuration that is pretty common:

The Antminer S9 uses a ton of power to run like most ASIC miners do.  It needs between 1300 and 1350 watts to run.  We’re going to round up in this article and call it 1400 watts.  This rate is similar to other devices on the market.

Most people don’t have the amperage they need to run more than a few rigs at home.  Let’s say you have three Antminer S9s you want to run.  The total wattage would be (3 x 1400) 4200 watts of power.  You can use this calculator to figure out the amperage you will need. According to the calculator, 4200 watts of power will require a little more than 38 amps.  In the US you will likely have 110v circuits in your house, and 15 or 20 amp breakers for each circuit. Your breaker box in your garage should be labeled to let you know what goes where.  Most bedrooms have multiple outlets connected to one breaker, so you can’t just plug the miners into different outlets.

Already we’ve ran into trouble.  We can only run one device per circuit, and at 12 amps a pop you can’t plug anything else into that circuit.  No fans, maybe a light or something.  Without spending money, you can’t really mine with more than one ASIC miner in your spare room.

The solution is contacting your local electrician and having 240v circuits installed in that room.  In my home lab (which was a bedroom when the kids lived at home) I had my local electrician install two 30 amp circuits.  The higher voltage lines have different plugs (L6-30P), so in addition to the installation costs we’ll need to buy a PDU (power distribution unit) to plug into our new outlet.  A PDU is basically a power strip so you can plug multiple devices into that one 240v outlet.

The PDU will plug into your miners and running 240v your power supply will run more efficiently and at half the amperage.  Half the amperage is the key.  That means our 12 amp miners now only burn 6-7 amps, and you can get all three machines on one 30 amp circuit.  Make sure before you plug in those power supplies that they auto-switch to use the 240 input.  Most modern supplies do.  The machines use the same amount of power from the electric company, measured in kWh.  The new circuit won’t make it any cheaper to run the machines but now we can run them off of one circuit.

Costs for installation of a new circuit vary.  My two 30 amp circuits cost 300 dollars to install and it was a relatively easy install.  My lab shares a wall with the garage so the panel was close.  The PDU we purchased cost a couple hundred bucks, so we’re looking at about $500 dollars to just deal with power.

If you can’t stand the heat

The second real issue with mining in the house is the heat generated.  Heat is measured from a formula based on the wattage the device uses.  Our three Antminers run 4200 watts total which equals 14330 BTUs of generated heat.  You can double check my math using this calculator.  For comparison my house uses a 4 ton A/C unit to cool the whole house.

A four ton A/C produces 48000 BTU of cooling (12000 BTU per ton) so these three miners need as much cooling as a fourth of my entire house.  If you close the door to this room (and it’s a standard size guest room) the temperature will increase at least 40 degrees, maybe more.  If you keep your room at 75 degrees, your room with just three Antminers will jump up to over 100 degrees.  You’re miners will not be happy in a room this hot, and the heat (and lack of humidity) could cause problems with the room itself.

There are two solutions.  One crappy and the other less crappy.  The first solution is to install a window unit.  You can get a big window mounted A/C unit for about 400 dollars that produces 15,000 BTU of cooling.  This device won’t really cool the room down, but it should keep the ambient temperature from rising.  This is a crappy solution because that A/C will need to run 24/7 and produces additional noise to your setup.  It will also burn about as much power as one of your Antminers which will bring up your electrical bill and make it that much harder to turn a profit from your machines.

The second solution is to exhaust the air to the outside.  Before we built the “mining cave” for our machines I had a few ASIC miners running in the spare room.  To keep the heat down I installed a massive fan to move the air out of the room.  This system work pretty well but you really have to have another window in the house open to equalize the pressure.  Without another window open the fan won’t be able to move much air and will eventually burn up.  Now you have two open windows in your house and you’ll have to pay more attention to weather.  You don’t want rain in your house.

A large fan still burns electricity but it will be much less than an A/C compressor would.

Not trying to hear that noise

The last issue we need to deal with for in-home mining is the noise.  And Antimer S9 runs at about 80db, which is as loud as a garbage disposal.  Three of them spun up in one room will sound like an actual server room.  Here’s video I found of one running:

As you can hear the S9 is not quiet.  Closing the door to your room will muffle the sound but since the pitch is so high a closed door will only help so much.  Having three units in your house (plus a huge fan to move the heat) will sound like a 747 in your bedroom. Your girlfriend will not be happy.

There are a handful of solutions on the internet for muffling the sound.  In my room we placed some sound-proof tiles on the walls but even then you could clear hear the machines running in the kitchen.  Many home miners build a soundproof box connected to ductwork that moves the air outside.  You can even use a cooler to kill the noise but you would need three coolers for our example.

It can be done …

… but you probably shouldn’t.  If you have the time, money and inclination though you can give it a shot.  You’ll need the help from an electrician and about a thousand dollars to do it right.  You’ll need to buy a PDU for your 220 outlets, a large fan and something to muffle the sound.  I eventually moved all our ASICs to the mining cave we made out of the shed in my back yard.  It took us all summer to build but it’s a better solution than a bedroom every day of the week.  Now I just run a few GPU rigs in my spare room, which is way less heat noise and power.

If you’ve built mining rigs in your spare room, tweet us a picture and maybe you’ll win a little hashing power from one of the machines in the lab.  Good luck.

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