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  1. #1

    Computer room HVAC set points

    I have a data center with three systems, 30, 20, and 20 ton Liebert DX units.

    I have the room configured with hot aisle, cold aisle. Using this configuration we have been able to turn up the temp set point on the units to 74 degrees. The servers are happy and the system admins and not turning blue anymore.

    But, our HVAC tech keeps turning the set points down to 68. When asked they say they run all computer rooms that way. Opinions? It just seems to use more energy and make the system work harder. Also seems to help over dehumidify too.

    We even lost the 30 ton unit for a few days and the two 20s kept the servers cool enough even though we were reading 82 degree return air temps.

    I know the set points are reading return air...so why set it so low? The unit will run 100% and never stage down.

  2. #2
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    Quote Originally Posted by dschultz307 View Post
    I have a data center with three systems, 30, 20, and 20 ton Liebert DX units.

    I have the room configured with hot aisle, cold aisle. Using this configuration we have been able to turn up the temp set point on the units to 74 degrees. The servers are happy and the system admins and not turning blue anymore.

    But, our HVAC tech keeps turning the set points down to 68. When asked they say they run all computer rooms that way. Opinions? It just seems to use more energy and make the system work harder. Also seems to help over dehumidify too.

    We even lost the 30 ton unit for a few days and the two 20s kept the servers cool enough even though we were reading 82 degree return air temps.

    I know the set points are reading return air...so why set it so low? The unit will run 100% and never stage down.

    70 degrees@ 50% humidity is the norm for computer rooms!



    .

  3. #3
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    Jan 2003
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    San Jose, Ca
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    It goes back to the old vacumn tube computers. Above 68 degrees you could get a stray electron, and thus courrupt data. There people out there who still think that computers will not work above 68 degrees.


    Computers do work at high temp. Above 90 degrees will shorten the life of hard drives and other parts. Between 80 and 90 some life shortening can happen.

    But the problem is convincing some people why computer room use to be kept low.
    Old snipes don't die they just loose their steam

  4. #4
    Join Date
    Mar 2007
    Location
    Melbourne,Aus
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    346
    Quote Originally Posted by dschultz307 View Post
    I have a data center with three systems, 30, 20, and 20 ton Liebert DX units.

    I have the room configured with hot aisle, cold aisle. Using this configuration we have been able to turn up the temp set point on the units to 74 degrees. The servers are happy and the system admins and not turning blue anymore.

    But, our HVAC tech keeps turning the set points down to 68. When asked they say they run all computer rooms that way. Opinions? It just seems to use more energy and make the system work harder. Also seems to help over dehumidify too.

    We even lost the 30 ton unit for a few days and the two 20s kept the servers cool enough even though we were reading 82 degree return air temps.

    I know the set points are reading return air...so why set it so low? The unit will run 100% and never stage down.
    Comfortable for humans....comfortable for computers. The computer dudes always like it cold as that is what they have been taught. Computers now days can handle anything upto 26°C + (79°F) without any problems. It is just a waist of energy and an additional cause to green house gases.

    The biggest problem is the correct air distribution and maintaining the correct temps at the servers. You can have a 21°C (70°F) temperature in the room measured by a room sensor but at the servers/rack it might be 28+°C (82°F) air distribution is the way to go!!!! My thoughts anyway!!!!!!
    Last edited by Ausccn; 06-11-2008 at 06:52 AM. Reason: Metric conversion !!!!!!! :)

  5. #5
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    Quote Originally Posted by Ausccn View Post
    Comfortable for humans....comfortable for computers. The computer dudes always like it cold as that is what they have been taught. Computers now days can handle anything upto 26°C + without any problems. It is just a waist of energy and an additional cause to green house gases.

    The biggest problem is the correct air distribution and maintaining the correct temps at the servers. You can have a 21°C temperature in the room measured by a room sensor but at the servers/rack it might be 28+°C air distribution is the way to go!!!! My thoughts anyway!!!!!!


    we seldom use Celsiuis here in America!

    i wish that we did use the metric system for everything here, but we dont!


    .

  6. #6
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    Mar 2007
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    Melbourne,Aus
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    Quote Originally Posted by Airmechanical View Post
    we seldom use Celsiuis here in America!

    i wish that we did use the metric system for everything here, but we dont!


    .
    What I cant understand is that when I watch Discovery or Nat Geo and they are US doco's they usually talk in metric units. Is that just for the rest of the world????? or just us dudes down here in Aus!!!! Airmechanical...you should be out on the job by now....shouldn't you!!!!!! I'm just having a couple of good Aussie beers after a hard days work.......

  7. #7
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    Quote Originally Posted by Ausccn View Post
    Airmechanical...you should be out on the job by now....shouldn't you!
    you sound like my old boss!

    maybe thats why i fired him



    .

  8. #8
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    Mar 2007
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    Quote Originally Posted by Airmechanical View Post
    you sound like my old boss!

    maybe thats why i fired him



    .
    he must of been a great dude....!!!!

  9. #9
    Join Date
    May 2001
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    Western Wa
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    Celsius?

    It's those dang British Thermal Units I keep having trouble with.

    They always come with metric threads.

    Then there's all this talk about sub cooling, and I ain't never been in the Navy.
    God Bless our Veterans

    God Bless the USA

  10. #10
    Thanks for the discussion.

    Actually it is the computer dudes that are turning blue and freezing to death in the computer rooms. Actually had HP engineers lay cardboard on the floor to block the airflow!

    I figured if the intake air to the servers in the the cold aisle was cool enough then return air temps could run higher that 72 without beating up the HVAC equipment.

    It took a while to explain that the hot aisle should be HOT!

  11. #11
    72-75*F 50% is fine.

    I set them for 73*F at start up. 68* is over kill and will cause higher stress on the units. Maybe they got sick of hearing about short cycle alarms?

  12. #12
    Join Date
    Feb 2005
    Posts
    27

    Question drip...

    doesn't Liebert "stress" low humidity, exactly how do you over dehumidify?
    If the zods are OK with the setup, and the room requires special handling[hence your bill], then who's giving a key to the light bulb changers anyway? Where are their orders coming from?

  13. #13
    Join Date
    Jul 2007
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    New Jersey
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    All of ours are also between 70F and 73F. Computers just keep sending heat. Its not like cooling off an empty room where the T stat eventually gets satisfied. This is a never ending marathon for the a/c.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

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