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  1. #1
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365

    cooling a small server room

    I have a small, rather dense server room that I need to cool. The total watts I have in there now is approx 12,000, plus the need to cool another unit that has a 2800 btu rating.

    I would like to be safe and be able to cool 17,000 watts of computer equipment. My question is, what is the smallest unit I can put in that will hold me over for now, and what is the size unit I should put in to allow for my gowth.

    humidity is not a problem b/c my systems can all operate between 10 and 90%

    I have gotten conflicting quotes anywhere from 3 to 5 ton, two speed and one speed systems. What would you suggest?

    I also have an Inergen fire supression system in there, just so you know

    Thanks for the help

  2. #2
    Join Date
    Oct 2004
    Posts
    43
    You should contact an area HVAC contractor. He will perform a load calculation, (Manual N) which will include heat gains from walls, roofs, windows and doors. That info along with the equipment, lighting, people load, and desired temp they will be able to select the proper system for you. There are way too variables to provide you with the size needed based off of the little information you have provided.

  3. #3
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    I wish it were that simple....I have had 3 of them come in, never saw any "load test" they all come and gather information and then tell me what I need.

    I feel that 3.5 ton is good for now, but not so good for future growth. 5 Tons I feel will be sufficient for my growth.

    here's how I came up with it

    12,000 btu = 1 ton
    my calculations came out the 3.4 btu is necessary to cool every watt (I have seen calculation on the Internet as high as 3.7)

    my projected equipment will be 15730 watts which would need 53482 btu which is about 4.5 tons, so if my raw calcs are correct a 5 ton unit would be perfect for me

    I heard a little about sensible vs lightened heat....The server room will be locked and we will only enter if necessary, so it should primarily be only sensible heat. Based on that, the one company I personally talk to say that my 3.5 ton unit will be suffice to grow into. My walls are drywall and my ceiling is acoustic tiles that are caulked.

    is a 3.5 ton two-speed system possibly enough for me to grow into? Is it plausible?

    Thanks for the help, I'm just a computer guy trying to make sure I get what I need


  4. #4
    Join Date
    Nov 2001
    Location
    East Texas
    Posts
    921
    This is not something you want to play around with. I take care of a com room. Get an experienced engineering company to size it correctly. Then you will need equipment designed for this application, such as Liebert,etc. In the future if you expand you can add another unit which will also provide you with a secondary unit for when one of the two fails. And trust me they all will have failures. The ambient temp can get over 100 very quickly you have a unit that is down.
    You must pm these units on a weekly basis.

  5. #5
    Join Date
    Oct 2004
    Posts
    43
    It's unfortunate that your area contractors couldn't provide you with better service. How about a mechanical engineer? They may be a little expensive but how important is the equipment you are trying to cool or the data they store and transmit.
    Something to consider if your real comfortable with your own calculations. If 53482 is all sensible than you need to find a system(s) that will provide you with that sensible capacity. A 5-ton will provide you at best 60,000 BTu total, but of that only 38000 to 39000 btu of sensible, the rest is latent capacity.
    You may want to call your area Leibert supplier. They specialize in computer room a/c. As much as we don't like it, alot of them sell direct to owners, and recommend a contractor to do the work.

  6. #6
    Join Date
    May 2002
    Posts
    9,564
    Liebert is overkill for this application 10-90% RH.
    How about your temperature restrictions? Can it be 75F in the room?

    What's the size of the room? Ceiling height? Square foot of outside wall? Windows? Size of windows?

    Then go with something smaller and when you add more equipment add another unit and then you have redundancy and neither unit will short cycle.


  7. #7
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    let me get that info....I don't have the exact specs....I don't remember off hand

    my head is spinning from all these numbers

  8. #8
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    You also need to figure for how many people are in the room. I agree with SYSINT on the 2 system setup for two reasons. Not only will you have efficiency but you will at least have one system working when one breaks down which is probably important for the conditions you mentioned. Also you may want to look into what kind of control systems each contractor offers. You want to be able to check and set temperatures from a remote location and you should be able to set it so it pages you in case it gets above a certain temperature in that area.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  9. #9
    Join Date
    Jan 2003
    Location
    San Jose, Ca
    Posts
    2,089
    Originally posted by thehumid1
    You also need to figure for how many people are in the room. I agree with SYSINT on the 2 system setup for two reasons. Not only will you have efficiency but you will at least have one system working when one breaks down which is probably important for the conditions you mentioned. Also you may want to look into what kind of control systems each contractor offers. You want to be able to check and set temperatures from a remote location and you should be able to set it so it pages you in case it gets above a certain temperature in that area.
    This is good advice
    Len
    Old snipes don't die they just loose their steam

  10. #10
    Join Date
    Nov 2004
    Posts
    4

    airflow

    The number one key to PC Server rooms is airflow.
    Air flow is the number concern in cooling this type of equipment.

    Here is the way to cool your equipment.
    1. Add up the name plat ratings of all computers, monitors, routers, hubs, switches, printers, etc.
    2. DO NOT INLCUDE POWER CONDTIONERS OR BATTERY BACKUPS (because you will be doubling your load and that would not be true since the power is passed through and not consumed at those points.
    3. The Total nameplate equipment watts is the MAXIMUM consumption of power. In the small PC and Server systems they NEVER use their max power. It depends on the actual usage but you can figure any where from 50% to 70% as your normal power load.
    4. Take the adjust Wattage and multiply times 3.413 and this will give you the HEAT put off by the equipment in BTUs. This is how much you have to take OUT of the room every hour. Divide this number by 12,000 and that will give the number of tons of cooling to offset that heat. EAXMPLE: 17,000 watts @70% load = 11,900 watts. 11,900 watts times 3.413 = 40,614BTU. 40,614 divided by12,000 = 3.38 tons of cooling.

    The real way to resolve your problem is to find a contractor that has SUCESSFULLY installed systems in server rooms. (GET REFERENCES AND CALL THEM). Don’t waste your time on engineers for this application.
    If you oversize you will create a high humidity environment, if you undersize it will be too dry and create lots of static electricity in your server room. Static electricity + Computers = BAD

    Since the computers will operate at a much higher temperature than humans, you do not need to remove all of the heat. In the example above 3.5 tons is WAY too much. In most cases a smaller unit will suffice. Air flow is the key.

    Just cooling your room wont do it. You need to move the air close to the floor and often. Make sure your contractor brings sheetmetal ducts all the way down to the floor where it can grab the heat from you computers. The air coming out of the grilles will probably be 55 degrees. The temperature on the CPU inside your computer is 110 degrees or higher and THAT is what you need to cool, the room is not important. Now how do you get the 55 degree air to the 110 degree CPU? Airflow, Airflow, Airflow.

    Don’t be tempted to resolve this problem by buying an air conditioner. This is a ventilation problem and should be addressed as such.

    You have three choices:
    1. use the existing building air to ventilate and cool the computers. ($800 - $2500)
    2. install a small air conditioning system ($2000 - $7000)
    3. Install a Liebert style air conditioner ($17,000 - $28,000)

    The main thing you need to do is to stay focused on the problem. The problem is not that your room is hot. The problem is not that your Computers are hot. The problem is that inside the case of your computers, your CPU and drives are hot. Even if you cooled the room the only way to cool the inside of the case is to move the air.

    I have successfully taken care of many computer rooms.
    Feel free to email directly if you want.
    Good luck.

  11. #11
    Join Date
    Jan 2004
    Posts
    1,176
    We sell alot of Sanyo splits for server rooms and they seem to work really well.I have a customer that put a 5 ton in his and he loves it.I have installed 2 , which is totally out of my usual work, but they worked great.

  12. #12
    Contact an engineer.

    Do NOT let this website design the system and make a selection for you. There are so many mistakes that might happen you will want someone who absolutely knows what they are doing, the codes, and the system to spec.

    Outdoor air, condesate drain lines, drycooler location, the list of potential problems goes on... Get an engineer to survey and design it. Also that way the responsibility is 100% theirs and 0% yours.

  13. #13
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Originally posted by marauderx
    Contact an engineer.


    Outdoor air, condesate drain lines, drycooler location, the list of potential problems goes on... Get an engineer to survey and design it. Also that way the responsibility is 100% theirs and 0% yours.
    Well I absolutely disagree with your "contact an engineer" and the assessment is 100% that an engineer is going to be 100% responsible if something goes wrong.

    "Do NOT let this website design the system and make a selection for you." VERY GOOD ADVICE

    "There are so many mistakes that might happen you will want someone who absolutely knows what they are doing, the codes, and the system to spec. "

    Someone who absolutely knows what he is doing, the codes and a system to spec 9 times out of 10 will not be an engineer but the HVAC contractor IMHO.


    [Edited by thehumid1 on 11-22-2004 at 10:08 PM]
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

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