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assessing heat loads

Data centers are an art first, with some basis in science.

If you took the connected nameplate load of all servers, blade servers, routers, processors, etc. you would be over-sized. Typically (and there is no such thing as "typically" with Tel-Data work), the diversity (=actual output versus potential output) can be 0.35 to 0.85. Take your pick! Well, not really.

Data centers thus are like snowflakes. You design to the nth degree and get it right with stated diversities or overall Watts per SF densities and then they expand... 20 percent used to be an acceptable reserve, but that could be void the week after you leave...

So what do you do?

Grab a copy of the ASHRAE Handbook of Fundamentals, latest edition and read the applicable sections. There were recent studies on actual outputs compared to nameplate potentials.

The other approach is redundancy capability. In other words, using more but smaller units allow you some standby capacity and the ability to "tone it down" should the room heat outputs be lower than you think.

Not a lot of help but that is what I can offer by remote..


  • assessing heat loads

    we have an opportunity to install an a/c system in the computer/server room for a customer, but we're finding various ways to determine the heat load. the software we tried came out to needing a 5ton unit, the actual watts/amps of the units comes out to about 3-1/2ton. and yet today, we measured the aperage at the panel of the wall sockets to be approx 15a.
    any experience at it? is there a 'best' way to do it?
  • exactly on the oversized

    we've already inherited an oversized/poor air flow mess from another installer and we don't want to create another for ourselves

    thanks for the input. i'll check the ashrae
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380

    If I were in your shoes, I would wholeheartedly buy into the redundancy strategy that Brad mentioned previously in this thread.

    Trying to get an accurate calculation result is diffucult at best, as not all pieces of equipment are functioning at the same time in addition to other variables that are in play.

    Although installing multiple systems may seem to be a waste of money from the first cost standpoint, it may actually prove to be a big money saver as compared to operating a single, grossly oversized system when the load is low.
  • thanks gene

    i passed brad's comment along, and i'll add your's monday when i see our 'calculator'
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    No Problem

    Please keep us posted as far as the ultimate determination goes.
  • mtfallsmikey
    mtfallsmikey Member Posts: 765
    Brad is spot on

    Having been involved with data center construction, all of the systems were designed with multiple units in lead-lag configuration, and for the most part grossly oversized per customer requirements. The equipment manufacturers can provide you with approximate BTU outputs, but getting thru to the right person is a pain..and in some cases only available to the registered user/purchaser. I have this problem now with a tenant who has servers in office space on one floor running 24/7/365, which drives the space temps into the low 90's during the unoccupied times.
  • well,

    we'll over-size it a shade and cross our fingers, because the customer's production from their mainstay biz is down
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    How much...

    How much is a shade?
  • don_185
    don_185 Member Posts: 312

    what about IQ Drive technology for one of these data center.

    No? yes? Maybe?
This discussion has been closed.