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  1. #66
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Yes I would concede that is it in a nutshell where we disagree and I may have been abrasive as you walked in the end of a long thread and where at first I doubted your ability to tie your own shoelaces(not bashing it is my general first assumption about everyone) I also concede that certainly is not the case and even though we differ on our opinions of a certain application I will say I respect the experience that arrived at it which is 10 years more than mine but again South Florida is a unique climate the southern most point in the U.S. so I feel my experience "in my backyard" is good and I understand your concern about the icing up of the system and in any other location of the U.S. would agree with you(except maybe Hawaii). The load calc without a crisatl ball I cannot really tell as the variables that have not been given are too many but I do disagree with your 5 ton assessment but understand why you arrived at it. Again also if I did agree with the 5 ton assessment(I do not) for this type of application would never reccommend installing a 5t system but 2-2.5 tons.
    I think besides my words in time if server reports back how the system works we will find which school of thought was correct. And you have kept me on my toes making think of why I know the things I know which is always good for my learning process or helps me get rid of faulty thinking when I have always done something a certain way maybe because I was taught it or whatever but then when examined I have actually no technical basis for why I do it. However,that I did not find to be the case here so:

    First I conclude that the Trane 3 ton system and the contractor selected by serverroomcooling meet with your approval. And two, I conclude no condensing capacity control will be required on this 3 ton split system.

    The above as you stated is my professional stance on this and I am sticking to it. Again #2 only because of the geographical location. Otherwise I would agree with that
    I think I explained my reasoning on the 3 ton which I know you disagree with which is ok with me.
    I believe I will be right in this case but that does not really matter the purpose of this thread was to offer advice to serverroom and I think he got more than he ever bargained for...lol. Ultimately it was his decision and he made an educated choice, he asked for advice here, got a 3 estimates I think, the contractor he chose did a load calc and is not some fly by night but already does work in his building.
    That was the purpose of this thread till it was hijacked by me to get in a peeing contest about what I know cause that is where I was born so to speak in the Hvac trade and so I am passionate about my backyard but I am willing to eat crow and Kowtow if serverroom comes back and updates us with a horror story.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  2. #67
    Join Date
    Nov 2004
    Location
    Atlanta, Ga. burbs
    Posts
    281

    Finally something I can talk about!!!

    I am an I.T. guy and have over-seen the building and or remodeling of computer rooms and data centers.

    The last time I managed a project it was a disaster from the A/C side. The HVAC pro. suggested the unit not be oversized. Well the guy, here, paying the bills said heck no bigger is better. So he had them drop in 15 tons which was contrary to the load calc. by the experienced HVAC person.

    So the outcome is as follows:

    Unit cycles on/off on/off all the time
    Room is not adequately cooled!!
    Bigger like my boss thought is not better.
    Paid way to much for excess capacity we can NEVER use since it is a high rise and the server room was built from smaller rooms.

  3. #68
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214

    Re: Finally something I can talk about!!!

    Originally posted by west_seth
    I am an I.T. guy and have over-seen the building and or remodeling of computer rooms and data centers.

    The last time I managed a project it was a disaster from the A/C side. The HVAC pro. suggested the unit not be oversized. Well the guy, here, paying the bills said heck no bigger is better. So he had them drop in 15 tons which was contrary to the load calc. by the experienced HVAC person.

    So the outcome is as follows:

    Unit cycles on/off on/off all the time
    Room is not adequately cooled!!
    Bigger like my boss thought is not better.
    Paid way to much for excess capacity we can NEVER use since it is a high rise and the server room was built from smaller rooms.
    Especially in Hotlanta gets as humid as South Florida there (just doesn't stay that way as long) but that is exactly why it is so critical not to oversize in our climate. On the West Coast, except for maybe the higher electrical from the cycling, it is not as critical because they don't have the moisture removal needs of our climate.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  4. #69
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Secking help in my train of thought

    Dear Thehumid1,

    I take extreme exception regarding the following statement:

    “…South Florida is a unique climate the southern most point in the U.S.”

    Hawaii is in fact the southern most part of any state in the United States….. Just kidding!


    Thank you as well for your words of respect. And yes, not only do I respect your 17 years in the business, but also your 12 years working in that area of the country.

    I would really like your option on one of my assumptions though. I’m basing my entire option of what I have been outlining by my posts on this thread on one thing.

    The following was posted by serverroomcooling on page 2 of this thread, second post from the top.

    “BBCMG04, great post....I have all that information, just never knew really how to use it properly. I have 52 AMPs running to a UPS and everything is plugged into it. I believe the line is 208 volts, which should be 10816 of average watts, am I right??”

    I took the 52 amps from above and multiplied it by the 208 volts to get 10,816 watts of heat being generated from the actual computer equipment in the room. I next multiplied the 10,816 watts by 3.412 to get 36,904 BTU of heat being generated from the computer room equipment alone. Next I took this 36,904 BTU/Hr of sensible heat(all heat generated from electrify is sensible heat) and multiplied it by 1.4 (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) and came with 51,665 BTU/Hr or 4.3 tons of cooling.

    I also remembered that serverroomcooling said the computer room was located on the top floor of a seven story building and that the computer room itself was approximately 100 square feet. I assumed there would be lights in the room and that people may or may not be in the room.

    Based upon the above information and formulas I made the following assumptions:

    1. Based upon “some” light in the server room the minimum interior heat load would be above 4.3 tons.

    2. Based upon whether the outside temperature was 90 degrees or 60 degrees, the structure load of the building would be adding or subtracting additional BTU to this minimum base interior load.

    3. Therefore, the cooling system required to work in this room would have to have a minimum capacity of at least 4.3 tons, but in fact the cooling load on a 90 degree day would be somewhat higher.

    Based upon the above train of thought, I concluded the 3 or 3.5 ton cooling system would not work on this project.

    Taking a step further, I concluded the contractor who supposedly ran a heat load calculation on this room and recommended a 3 ton system did not do his job right from the very beginning of this project.

    Thehumid1, would you please review my train of thought and help me see where I made a mistake regarding this project.

    Your anticipated help is very much appreciated. Waiting for your reply…….


    Respectfully Submitted,
    John J. Dalton




  5. #70
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    well guys....I have an update. We put in a 3 Ton Trane unit, split system....the handler is in the front corner of the room (blocking my window, but at this point I could careless), the condensor is on the roof.

    All but one of the ducts are up and running, but we have begun testing the unit. There are missing ceiling tiles, which means there is a lot of flow up into the ceiling since the main return for the floor is on top of my server room, but the room still cools down to 70 degrees and the system shuts off for about 7 minutes before turning on again....I would think that once the ceiling tiles are put back and caulked (as I need to do that for my inergen fire system) the room will stay cooler for longer.

    Is that good? Is 7 minutes off the handler shutting off good for the system?

    so far it seems to working good. I shut off my portable spot coolers and things are much cooler now than with the spot coolers.

    The avg temp now is much lower than a few weeks back....it's 70 today, and will drop under that, but it still gets hot up here in the building. The thermostat on the handler was reading 86 prior to turning on the unti, and now it reads 69/70 and turns on if it get hotter than that.

    I'll be monitoring closely, any advice you might have would be greatly appreciated

  6. #71
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Ok here where is where I think you have erred in your ways.


    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.
    which is the 3 tons the contractor installed.

    Why?
    Next I took this 36,904 BTU/Hr of sensible heat(all heat generated from electrify is sensible heat) and multiplied it by 1.4 (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)

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

    However the load of 36,904 needs to be reduced by between 50% to 70% per point #3 made at the top of this post. To be generous we will figure 70%. So the 30% the load is reduced is a wash out with the 30% capacity multiplier.

    Which leaves a load of 36,904. Making three tons a good choice maybe a maximum of 3.5 tons depending on other factors and conditions of the room.



    FOR SERVERRROOMCOLLING: MORE IMPORTANT THAN HOW LONG IT SHUTS OFF MONITOR HOW LONG IT RUNS FOR AND HOW MANY TIMES IN ONE HOUR MIDDAY IT CYCLES ON AND OFF. ALTHOUGH IT WILL CYCLE MORE THIS TIME OF YEAR AS THE OUTDOOR AMBIENT IS LOWER THIS TIME OF YEAR REDUCING THE HEAT LOAD IT SHOULD BE RUNNNING 5 MINUTES/OFF 7MINUTES,RUNNING 5 MINUTES/OFF 7 MINUTES AS THIS KIND OF CYCLING IS NOT GOOD MONITOR IT AND POST IT.THANKS.



    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  7. #72
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    ALSO MR DALTON GUAM IS ACTUALLY SOUTHERNMOST POINT LOL... LET ME KNOW IF MAYBE I MISSED SOMETHING IN MY PREVIOUS POST BUT THATS HOW IT LOOKS TO ME THRU MY BEER GOGGLES!
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  8. #73
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    I will try to monitor the cycles...I guess the best way for me to do this is to sit in there for a few hours and just jot down when it goes on and off

    here's what I have so far. I have a monitoring probe on my power subsystem. last night with just the spot coolers going, the temperature on that probe (which is inside the unit somewhere) was close to 90. right now, it bounces between 80 and 81 with occassional spikes to 82 and 83. This is great because at night the temp in the building rises as the main AC in the building is off. The bad news is that I can't monitor AC cycles at night, but I like the fact that I can monitor the temp inside the power device. It's a pretty good point of reference....it's probably the hottest area of the room.

    Early indications show that we are doing much better than we were last night....all I can do now id hope and pray that the unit holds up.....I'll continue to update

  9. #74
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Are you saying in addition to the newly installed system you are running spot coolers as well in the same conditioned space and if so where are you venting the hot air from them too? What exactly are you taking the temperature of that was 81 degrees is that a probe inside one of the server machines?
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  10. #75
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    the spot coolers are off and have been off since 2:30 earlier this afternoon, so only the new 3 ton AC unit is working now. The probe...I'm actually not sure exactly where it is. I don't think it is the internal temp, it must be a probe near the outside of the unit, probably near the back....the unit is near the back of the room where the room begins to go to the point of the triangle. The last duct will be right on top of that area, and should be installed in the morning.

    the handler is pulling air out of the room, and the opened ceiling tiles are also sucking air out, but that is only during regualr business hours, after hours the main building AC is off, so so the returns are not sucking air out of the server room.

  11. #76
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Are you telling me besides the 3 ton system a main building a/c has a return in that room? is that correct?
    does it have a supply drop too if that is correct?

    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  12. #77
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    the server room is eventually going to be sealed off from the main building AC...right now it is not b/c we have ceiling tiles that are unsealed and moved to finish the duct work. Tomorrow, when the duct work is finished I will close the ceiling and seal up all the holes.

    directly on top of the room is one of the main returns for the floor. When the ceiling is sealed, that return has very little affect on the room. I know this b/c of the door pressure test that was done prior to passing inspection for the Inergen fire system.

    so right now, I am being affected by the main building AC, mostly during the day, but that is only temporary....there are no vents that blow into the server room from the main building AC

    So right now, there is 3 tons of AC being pumped in from my seperate Trane unit, and things look like they are holding up.

  13. #78
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    the return for the building is up in the drop ceiling directly above my server room

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