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I've got the following gear in a small 120sqft room. While AC is supplied it's a home/office and in the summer both the central air at full go and a standup indoor portable AC on full barely keep it below 25-28c.

  • 4 servers HP/IBM 4u/5u
  • 1 24port switch
  • 1 1300va UPS
  • 1 3000va UPS
  • 4 routers/wireless aps
  • 4 lcd monitors
  • 1 workstation

I'd done some reading when working on a clients server room and read 220v is more efficient and generates less heat. But will it make any significant difference when the real culprits being the servers get switched to 220v? I might even go down to three servers this summer to help the heat situation.

The electrician quote about 400$ to run the BX cabling and install a new breaker. I've gotta use the BX armored cable because I'm in a older condo building.

I'm also going to have to spend money to replace the UPSs with 220v units.

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  • Slightly off topic, but do you actually need all those servers? If they are just for software development testing, consider using one more powerful machine with lots of VMWare images. I replaced 4 huge servers and 3 workstations, with a single super powerful workstation (all for development/testing) and electric bill and noise went way down.
    – EJB
    Apr 17, 2011 at 20:32
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    EJB, the servers run ESXi and have loads of VMs on them. One server is pretty much dedicated as a SAN server with 15K SAS disks and 7.2k SATA storage. One server doesn't need to be on, but is once in awhile for testing. But two minimum as ESXi is configured with HA/DRS etc plus the SAN for shared storage. So I can't get below three. I've purchased a new server in which I might be able to virtualize the SAN OS and use VT-D to passthrough the Raid card into the VM. I'm just a little worried about having my SAN and ESXi environment in one getup..
    – Garuda
    Apr 19, 2011 at 2:28

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The efficiency improvements you get from moving to 110v to 220v are not that great. Yes, there is less heat, but we're talking a few percentage points. The few things I've seen, generally in commodity hardware not server hardware, show efficiencies moving from 83% to 86% efficient, or +3% efficiency. That can add up if you have a 10K sq/ft room full of stuff, but for four servers it barely twitches the needle.

Overall, I think going to 220v is a good move. However, cooling improvements aren't going to be how you get that move justified.

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  • More voltage = less current to provide the same potency, so you can also use thinner cables (easier to manage).
    – coredump
    Apr 17, 2011 at 13:47
  • @coredump Rephrased slightly, when supplying a device with a specific wattage, upping the voltage means lowering the amperage. Therefore, you don't need as thick cables to make it work (16ga vs 14ga).
    – sysadmin1138 ♦
    Apr 17, 2011 at 13:49
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You won't have much improvement by switching from 110v to 220v, If cooling is your issue you should invest in a better a/c, These portable units don't cool as good as seperated stationary units, I think this is your best bet.

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  • issue is the window is some 18inx18in. not exactly something I can put a AC unit in.. do you have any recommendations on a stationary unit? and ballpark costs? I know the portatable unit I have only blows cool air, not cold.. Thanks!
    – Garuda
    Apr 17, 2011 at 15:27
  • I can't give you any recommendations, but for example look at some of these airconditioner.com/MINI_SPLITS.asp Perhaps you're best off by going to an expert on this... But from my experience, split units work way better then window or portable units
    – HTDutchy
    Apr 17, 2011 at 17:27
  • thanks! I've seen split units in restaurants before. Will have to research costs.
    – Garuda
    Apr 17, 2011 at 21:50
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In general this is quite simple thing. You get more power with either higher voltage or higer current (or both). The higher current flows the heater its conductor is. So, it looks like that having higher voltage is better since it means less heat release.

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  • This is why the higher voltage circuit is more efficient at getting power to the plug, but is irrelevant to the discussion of the equipment releasing heat that must be removed from the room.
    – tomjedrz
    Apr 17, 2011 at 20:27
  • Well, actually you're right; the device itself works out the same quantity of heat, and the only difference is current flowing to it. Only for real big server farm that difference would be noticable, of course.
    – poige
    Apr 18, 2011 at 3:25
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For starters you could approximately measure how many BTU your equipment is generating. From there you could get appropriate A/C, which blows cold (not cool) air. Think of ways to isolate the rack and the A/C into a small "hoot". Smaller area, easier to cool. I don't think switching to 220V will solve the heating problem. Here MovinCool you can find some good home and professional grade portable units. Also, most of the modern home portable units, which you can find in BestBuy and similar have self-evaporating function and come with a window adapter. One of this is $400-500 for 10000BTU.

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  • yea i've got one of the portable ones with a window adapter. 10,000 btu or so it says.. but barely any cold air escapes it.. cool yes. cold no.
    – Garuda
    Apr 17, 2011 at 21:51
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Don't do it .. you will be wasting money.

Switching to 220V will have no impact on the heat generated by the servers. It might save you a few pennies a month on your power bill, but with only 4 servers, there is no chance it will pay for itself any time soon.

The unit of energy is the WATT. A server draws N watts, whether supplied by 220V or 120V. Some of that energy is used by the system to do it's thing, the rest is released as heat into the room.

The higher voltage circuit is more efficient at getting energy to the plug, which means that fewer watts are required from the grid in order to deliver N watts to the server. But energy lost in the circuit is trivial from only the 4 servers, and isn't lost in the server room in any case.

You just need a better A/C unit. A quick and dirty calc ... total the rated watts of the equipment in the room and multiply by 3.5 to get the rough BTU/hour generated by the equipment. Get that much BTU of A/C, and you should be fine.

Note #1: this is a gross simplification, and it is possible that some power supplies are more efficient at different supply voltages and so will pull different wattage to deliver the same internal power, but the difference is tiny.

Note #2: If you want to verify .. try an on-the-fly voltage converter. http://www.quick220.com/220_pictures.htm

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