cooling a small server room - Page 7
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  1. #79
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    I know this b/c of the door pressure test that was done prior to passing inspection for the Inergen fire system.

    I am not sure I know what you mean by this are you talking about a blower door test?

    You really dont want a another system in play in the room especially only a return and here's why when your room reaches design temperature (the temp you set your thermostat too) and the main building a/c is on what will happen is that return will suck your conditioned air out of the room and since no air is being put back in the room by that system it creates a negative air pressure in the room which means the room is going to be sucking air in from wherever it can cracks in the walls,doors, exterior windows, ext anywhere it can to stabilize the pressure void caused by the air being sucked out by that return. So not only does it suck out your cool air it draws in hotter air to the room this will cause your unit to cycle more cause every time it reaches design temp when the main a/c is running the air gets immediately sucked out.

    This is not good. Make sure it really is sealed personally I would insist on that return being capped off if I was installing your system but if what you are telling me about
    the test you had done if it was a blower door test it would tell you how much infiltration and would be extremely accurate if it was done correctly but I am still not sure I would take the chance as once the new system is installed the return has no reason to be there other than to cause a problem. To begin with that design was not good as air should be balanced. It is impossible to be perfect but the goal is to put back in the same amount of air that you take out of a room so neither a positive or negative pressure condition occurs here that wasn't even being attempted.

    What size is this return?
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  2. #80
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    It's a very large return and can not be capped off, I lost that battle a long time ago, I did not want the server room in there for that reason.

    The door blower test...I don't know the lingo, but it was a big fan that was placed in the doorway. The entire door was blocked up and the fan was blowing inward for one test and outward for others. The goal of the test was to prove that the room was sealed properly to make sure that the inergen gas would stay in the room upon discharge, at least long enough to displace the oxygen so it would extinguish the flames. For testing purposes that time is 10 minutes.

    when the ducts are finished I will be sealing the room personally as I have been doing every time we need access above the ceiling. I use silicone caulk as well as grout and spackle. Obviously it is not perfect, but I think it is certainly adequate.

    Right now, as the mail building AC is on, the low temp on my probe is 78, and on/off cycles seem to be in the 10 minute range...I will be spending time in the room to get the real on/off cycles after I close the ceiling. I will report back

  3. #81
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    That is the test it is called a blower door test. Was it tested with the return off or on or both hopefully.
    Anyway,if nothing else is above the space and you don't to access that space sheetrock would be better than a drop ceiling with tiles.

    At of the things spoken about in this thread my biggest concern would be about that return had you mentioned that at all in your earlier posts?
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  4. #82
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    Thanj you for your response

    Dear Thehumid1,

    Thank you for the response, but as I’ve said before, if you’re going to quote me, quote me correct:

    “ALSO MR DALTON GUAM IS ACTUALLY SOUTHERNMOST POINT LOL”…

    I actually said:

    “Hawaii is in fact the southern most part of any state in the United States…..”


    Hawaii is the southern most ….<STATE>……in the United States….Guam is a territory of the United States…..lol.

    Seriously,,,thank you for your response.

    Regarding your quote:

    Note the prior post to this By Bbcmg04: 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.

    Also I am assuming serverroom is correct that he has 208v not 120v to all the equipment and the total rated amperage on the name plates is 52 amps. Which gives 10,816 watts x 3.412=36,904 which becomes the load for the room.

    According to serverroomcooling in his post on page two, post two of this thread……

    “I have 52 AMPs running to a UPS and everything is plugged into it. I believe the line is 208 volts”

    I assumed that meant he was actually pulling 52 amps at 208 volts (single phase of course), when he had all his equipment turned on.

    I guess this would be a clarification question for serverroomcooling????

    Next you stated:

    “I am not forgetting this point you made(first the multiplier should x 1.3 not 1.4 that would represent 60%)”

    If all standard HVAC units with anywhere between 400 and 500 CFM/per ton will only put out approximately 69 to 73% sensible heat from their total BTU capacity, then the formula would in fact be:

    Sensible BTU / Total BTU = % of sensible to latent heat

    Which is equal to:

    Total BTU / % of sensible to latent heat = Sensible BTU

    Given that at 69% to 73% sensible heat, the multiplier would be between 1.4492 and 1.369, hence the rounded 1.4 multiplier. Using a factor of 1.3 would mean that the HVAC system would have to have a sensible to latent heat factor averaging 76.92 %, which no standard manufacturer has given the limitation of 400 to 500 CFM/ton of cooling.

    Also you stated:

    “Making three tons a good choice maybe a maximum of 3.5 tons depending on other factors and conditions of the room.”


    I agree with you that the total computer equipment load MUST be added to “other loads”….such as the building structure load, the room lighting load, the people load if any, and so on. And it seems the outside glass load, as serverroomcooling mentioned in his last post.

    But……again we can agree to disagree……lets see how the finished system is running….

    Respectfully Submitted,
    John J. Dalton

  5. #83
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    this thread is so long.....I don't remember if it was mentioned.....the ceiling tiles were tested both with the return on and off....it's a pretty tight seal

    sheet rock ceiling....I wanted that as well, but lost that battle also....I didn't want this room in the first place

    I have baselined the cycles of on and off times with the tstat set at 70 degrees and the ceilng tiles open. The last duct will be finished today and I will close the ceiling up as soon as they are finished and baseline again.

    What are acceptable on/off cycles for this system? Should I set the tstat low enough that it will never shut off?

    The room heats up about 1 degree a minute, so it will never sustain the temp for more than 5 minutes (at least now with open ceiling, it may hold temp a bit longer with the ceiling tiles closed up)

    The handler is a Trane model TWE036P13FB0 in case you were wondering what equipment I got

    I will follow the suggestions of my AC guy as it is his system and he says he will stand by it...but I do take the information I learn here and have him answer all my questions. He never seems phased by the questions and answers them satisfactory.

  6. #84
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    "sheet rock ceiling....I wanted that as well, but lost that battle also....I didn't want this room in the first place"

    Serverroomcooling you need to read Dice's 9mm thread and start carrying one and you will win more of those battles.

    Mr Dalton I did misquote you on the hawaii thing, just consider it a failed attempt at humor. i promise not to quit my day jobs.

    Yes we do agree on the extraneous load factors but
    did you see the point I was making about the tonnage?

    You figured 60k for the load based on full load amps which will never occur. It should have been considered at 50-70% less than that then add back your 30% capacity multiplier which leaves you back with the original load total of 36k.

    But I must say you are a very formidable opponent in "HVAC" chess! I would even let you work on the system in my home,
    for free of course as one professional to another just so I could see how they do stuff in your neck of the woods.

    Serverroom you cannot really start examining the cycling of the system until it is completely installed and the ceiling is closed back up.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  7. #85
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    The biggest thing to me besides the not mentioning the window in the room was the return from the other system being in there. That truly is what could kill the system design d but it seems he and his contractor have already taken that into consideration. X factors like that are scary cause sometimes they can be overlooked when bidding the job. Then the system does not work and the customer starts thinking oh by the way I have this...and ultimately your responsible cause being the professional the judge will say:I expect the client to know nothing... he hired you because you are supposed to know everything. Thank god for me it never ended up that far ever and I was able to correct design flaws(I know it is hard to believe but I have errred in making load calculations. Either by not including a X factor or sometimes the reverse.... a mistake as dumb as counting the first floor ceiling as an exposed ceiling.) Check,double check, drink heavily, go back to the site check and double check again then pray for the best.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  8. #86
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    A thought

    Dear serverroomcooling,

    Based upon the information supplied by your most recent posts, it would appear your building has a common return air attic, a design commonly used for larger central HVAC plant designs in low and mid rise buildings such as yours.

    Your correct in your statement that after the ceiling tiles are installed and sealed in your server room, this common return air system will have no adverse affect on your dedicated server room cooling system.

    If fact, whenever the building HVAC system is on, your room’s heat load will be less because the ceiling/attic heat gain will be reduced. However, whenever the buildings HVAC central plant is off, you’ll be under the full heat load of the ceiling. Based upon experience with this type of system configuration, your time of greatest heat load will be under the following scenario:

    A given holiday Monday(Memorial Day or Labor Day for example) afternoon between 2:00 PM and 5:00 PM(insulation lag time), the building would have been closed on Saturday and Sunday, therefore the built-up heat from almost three days without the A/C running will be its greatest.


    Respectfully Submitted,
    John J. Dalton

    PS: Nice to see another dedicated professional, even if he’s an IT guy…..lol
    Last post of last night, or should I say of early this morning:12:29 AM. Sure hope your boss appreciates your dedication to completion of this project.

    PSS: Nice to see your HVAC guy isn't phased by all us here on this forum second guessing him. And nice to see he's answering all your questions.

  9. #87
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    Your move I think.....lol

    Dear Thehumid1,

    I don’t agree with your last statement…….I think the humor you have shown of this thread has earned you a spot on stage……….but unfortunately, like my own humor, that stage should be the one out of town!

    And thanks for the vote of confidence regarding letting me work on you’re a/c at home, but we don’t do residential, only commercial, industrial, and institutional systems…..sorry…..lol.

    Respectfully Submitted,
    John J. Dalton

    PS: I like our chess match as well…..and incidentally, Serverroomcooling DID NOT mentioned the common return air inlet duct above his server room. That would have set off bells and whistles like it did, until he clarified what type of building system he has.

  10. #88
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    Stop testing.....

    Dear serverroomcooling,

    Like my colleague stated in his earlier post. Stop testing till the following:

    1. The HVAC system is complete.

    2. The ceiling tiles are re-installed and sealed.

    3. The spot coolers are turned off and out of the room.

    4. The system’s thermostat has been configured, programmed, and set per your contractor’s recommendations.

    5. Then and only then state testing the system.

    Will post on what I would recommend to check for in regards to testing in a few minutes.

    Respectfully Submitted,
    John J. Dalton

  11. #89
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    Dear serverroomcooling,

    By the way,,,,,do you have an estimated completion time of the above items?

    Respectfully Submitted,
    John J. Dalton

  12. #90
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    Originally posted by john dalton
    Dear serverroomcooling,

    By the way,,,,,do you have an estimated completion time of the above items?

    Respectfully Submitted,
    John J. Dalton
    Hopefully not till after Christmas I need to get out of the black hole I got sucked into on this thread...I swear it will never end unless I get in the LAST WORD...lol!

    Stage out of town I liked that...maybe I will take it to your town next !!!

    Just in case you didn't see my post in the general thread about ID's at the border....I have been kicked out of better places than Canada ...now that I think about it that does not really say much.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  13. #91
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    Re: Your move I think.....lol

    Originally posted by john dalton
    Dear Thehumid1,

    I don’t agree with your last statement…….I think the humor you have shown of this thread has earned you a spot on stage……….but unfortunately, like my own humor, that stage should be the one out of town!

    And thanks for the vote of confidence regarding letting me work on you’re a/c at home, but we don’t do residential, only commercial, industrial, and institutional systems…..sorry…..lol.

    Respectfully Submitted,
    John J. Dalton


    Well actually you can do my home if you do institutions... well I think pysch ward is considered institutional I will ask the doc when I re-up on my anti-homicidal meds.
    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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