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  1. #1
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    Datacenter cooling

    To determine the cooling req. for a datacenter how many BTU are required per square feet?

    Does under-floor (raised floor) requires cooling as well?
    Joman Sierra
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  2. #2
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    I know raised floor should be kept cool just becasue there hidden doesn't mean they are not important. Not sure of BTU I know right now my telco hotel houses 20TON Liebert's for 4,000 SQ FT.
    Axcelx Technologies - James
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  3. #3
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    The under-floor/raised floor is where the cool air is pushed through by the HVAC (High Volume Air Conditioning). Then, the cool air will go up through small holes on the floor to cool the equipment above it. So, underneath the floor is actually cooler.
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  4. #4
    HVAC is actually a general term for "Heating-Ventalation-Air-Conditioning" not "High Volume"


    20 Tons for 4,000 SqFt is actually somewhat undersized depending on the floorplan of the room. For the most part, you will want 250 BTU/sqFT for all of the areas that will contain equipment and less for aisles and open spaces.

  5. #5
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    Originally posted by DoubleD
    HVAC is actually a general term for "Heating-Ventalation-Air-Conditioning" not "High Volume"


    20 Tons for 4,000 SqFt is actually somewhat undersized depending on the floorplan of the room. For the most part, you will want 250 BTU/sqFT for all of the areas that will contain equipment and less for aisles and open spaces.
    Ah, that's right. HVAC is Heating, Ventilation & Air Conditioning and not High Volume. Thanks for the reminder DoubleD.

  6. #6
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    that is definately undersized depending on the application.

    if you are housing a lot of servers you will need 20 tons per 1000 in a N+1redundant format of cooling.

    so if you have 4000 sq ft of servers - you will need 80 tons + another 20 ton unit (if you units are 20 tons each) in case one goes down.
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  7. #7
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    There 2 20Tons so 40TON's total and the SQ FT is 3,200 I belive. Is that good? I know the room is on the cold side and 75% full.
    Axcelx Technologies - James
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  8. #8
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    Originally posted by Crucial
    There 2 20Tons so 40TON's total and the SQ FT is 3,200 I belive. Is that good? I know the room is on the cold side and 75% full.

    well - the question is - what if you lost a compressor? what if you lost a fan belt on the blower on one of them? what if you lost one of them due to electrical problems etc.

    would the other one hold the temp till the first one is repaired?

    will they hold the temp when you are full?

    do you have electric capacity to add another one?

    what percentage of the time are both compressors in the units running now? are they on 100% meaning you are at or near their total heat exchange limit already?

    do you have outside coooling capacity to add another one?

    those all need to be answerd,
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  9. #9
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    Electric is not a problem, There not even at 50% on both 20TON and yes there is outside cooling capacity. I belive when the room is filled it will be around 50% on each. So if One fails I guess they other will be 100%.
    Axcelx Technologies - James
    Boston Colocation | Boston VPS
    Massachusetts Server Colocation and Dedicated Servers

  10. #10
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    Definitely raised floor datacenter is harder to maintain.

    Thank you all for your usefull opinions.
    Joman Sierra
    http://www.dominet.net

  11. #11
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    40 tons, 20 tons or 80 tons of air ? they are all the right answer depending on how many servers you plan to place in the space and KVA load.

  12. #12
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    N+1 means for each 20 ton unit you have a spare 20 ton unit. For example, we have ten CRAC (HVAC units designed for data centers - stands for Computer Room Air Condition) units and only five run at any one time. Therefore, if one of the units has a health issue, it can be taken off line and the alternate started to take its place.
    Brad @ Xiolink
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  13. #13
    I swear I thought N+1 mean Number+1, so you take the number of HVAC units you need and add one... It wouldnt really make sense to have a backup for EVERY unit, they arent ALL going to go down at the same time... or maybe at MOST two will go down (N+2)...? Maybe I'm wrong.

  14. #14
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    f0urtyfive,

    I believe you're right. What Brad is talking about is 2N reliability :-)
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  15. #15
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    It depends on how your datacenter is set-up. For example, our datacenter is zoned so in each zone there is one unit with one backup. Each zone (5 zones in our Datacenter) has a primary unit and a backup.
    Mike @ Xiolink.com
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    "Your data... always within reach"

  16. #16
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    Originally posted by f0urtyfive
    I swear I thought N+1 mean Number+1, so you take the number of HVAC units you need and add one... It wouldnt really make sense to have a backup for EVERY unit, they arent ALL going to go down at the same time... or maybe at MOST two will go down (N+2)...? Maybe I'm wrong.
    when I refer to N+1 I mean that you need one extra unit in case one goes down.

    not duplicate units for every unit. that wold become ungodly expensive.

    also - all oyu need to do is replace the tonnage cooling in the room that is missed.
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  17. #17
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    People often overlook distribution when assessing HVAC redundancy. If your cabinet of expensive blade servers fries because the hvac unit at your end of the data center goes out, a standby unit at the other end of the data center that can't get the cooling to you does not offer much consolation. Call it what you will, your blades are still fried.

  18. #18
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    Originally posted by BandExch
    People often overlook distribution when assessing HVAC redundancy. If your cabinet of expensive blade servers fries because the hvac unit at your end of the data center goes out, a standby unit at the other end of the data center that can't get the cooling to you does not offer much consolation. Call it what you will, your blades are still fried.
    that is correct - that is why it is good to have a data cetner that has circular cooling flow patterns so that each unit is in fact adding to the sum of cooling of the entire data center. this depends on placement and ventilations system and aiming of vents.

    also one should have an ir temp guage so you can fine tune this in the dc. very helpful.
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  19. #19
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    But doesn't an IR gauge only measure surface temp? Does not help with atmosphere.
    Mike @ Xiolink.com
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    Advanced Managed Microsoft Hosting
    "Your data... always within reach"

  20. #20
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    Originally posted by RackMy.com
    But doesn't an IR gauge only measure surface temp? Does not help with atmosphere.
    yes it measures surface temp and you can use that as a guage. it works great - ever use one?

    best tool I know of.
    Dedicated Servers
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  21. #21
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    <Drinking to much. Zeros were in the wrong place. >
    Last edited by WII-Aaron; 05-25-2004 at 10:52 AM.
    Aaron Wendel
    Wholesale Internet, Inc. - http://www.wholesaleinternet.net
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