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  1. #170
    Join Date
    Jun 2001
    Posts
    3,913
    This is a very informative thread. Out of curiousity what type of filtration is being used ?

  2. #171
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    I think it's regular old 20 x 20 x 1 fliter, nothing special to my knowledge

    this thread is the size of a book, I know I'm learning a lot, I have a new found respect for hvac guys

  3. #172
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Need Clasification......

    Dear Serverroomcooling,

    Is the following true with these actual sizes??????

    Is that a grey 12” round (12” inside/14” outside) flexible duct attached to the above transissional box running to the attic?

    Respectfully Submitted,
    John J. Dalton

  4. #173
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Serverroomcooling,

    Regarding the following statement:

    “…rep from APC (American Power Conversion) who specialize in these rooms.;;;”

    Does this guy know these rooms…..or does he know UPS systems….or is he an expert in HVAC specializing in this type of room? There’s a great difference here!

    Respectfully Submitted,
    John J. Dalton

  5. #174
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Not to add insult to injury, but.......

    Dear Serverroomcooling,

    In addition to the undercharged system which we’ll deal with after you get us those readings. I’m thinking we have another potentially larger problem dealing with an insufficient amount of airflow through the air handler. I’ll wait for your answers regarding the ducting off the top of the air handler.

    Respectfully Submitted,
    John J. Dalton


  6. #175
    Join Date
    Sep 2002
    Posts
    1,389

    reply

    At this point a full set of operational readings must be presented here. First off I am not sold on an undercharge if the total cfm if high. Secondly if the racks are to be addressed for colder air, more registers and their respective throws had better be corrected.
    Reasons:
    1. System doing 15 degree DeltaT. At the same time the return air entering the coil I believe was around 67-68 degrees. Below operating criteria for this equipment and the use of an expansion valve especially if there is no head pressure control.

    2. Why, if the room and racks are 72-74 is the return air at 67-68. The floor return is seeing a short-circuiting of supply/return air before it can be used for rack cooling. The return should be at or above rack temperature for near 100% efficiency of the system. With cold return air, a lot of air is being wasted and is off-loading the refrigerant circuit.

    3. If I am not mistaken I read somewhere the room RH is going up during the off cycle. If so where is the humidity coming from? As room temp increases with no additional introduction of water molecules the RH reading should be going down.

    Fix the air flow, fix the refrigerant system, fix the drain if required, put the room in a slight positive and it will work.

    I would just like to see a full set of readings as is done with a proper start up.
    tom

  7. #176
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    I'm going to call him now to see if I can get him to send a tech over to grab the readings. If he can't send someone or deosn't cooperate, I'll call some other guy and pay him to gather the numbers for me.

    I'll measure the duct above the handler soon

    the APC guy is not an hvac guy, he's more of a room specialist.

    There is a supply vent very close to the return grill, as pictured in one of the posted pics, maybe that supply vent should be closed, it is probably what is causing the air to be colder than the the room, as that air drops into the room and is sucked into the return very quickly...just a thought.

  8. #177
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    RH seems to be going up and down during the cycle, and that is read from the accurite digital thermometer. The regular thermometer and humidity readers I have on the walls of the room seem to be more stable and don't fluctuate too much. I'm not sure of the quality of them, I bought them at Home Depot in the outside gardening section

  9. #178
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    my hvac guy said he would stop by either this afternoon or tomorrow to get those readings

  10. #179
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    he also told me that we should upgrade to a better thermostat that we can program.

    He says that he feels there is a bigger risk of freezeup while the building AC is on, and we will program the server room AC to drop to a lower temp when the building AC goes off at nights and over weekends and holidays.

    He feels that even if the system is off for less than 3 minutes, it should not cause the a freezeup.

    the vent above the handler is 16 x 20.5, and goes up into the drop ceiling where it is ducted into the room. The ducts appear to be 12 inches in diameter

    That APC guy I mentioned before is not an hvac guy, but has extensive experience in server rooms. I am bringing him in mainly to fit me with a server room monitoring system that will alert me to problems before they happen.

    I also would like to keep a spot cooler and set it up in a way that it will turn on as soon as the temp reaches the alarm threshold. This way I will be notified and I will walk into the room before a melt down since the spot coolers will keep the racks cool, but that's for later

  11. #180
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    twcpipes.....I do not have a raised floor in my server room, the air comes in from the ceiling vents. I would love to have a raised floor with air coming up from the floor, but that was not an option I could even ask for. I wanted a bigger room, didn't get that either. I'm working with what I have, and we will get this to work.

  12. #181
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    here's another thought.....I have fans mounted on top of my server racks, they pull hot air out of the racks and bring that air to the ceiling....that is where the supply air comes from, maybe I should not be moving that air up to the ceiling where it mixes with supply air??

  13. #182
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Good Morning Tom

    Dear Twcpipes,

    First and foremost Tom, I think we can both whole hardly agree that diagnosing under the present conditions can very problematic at best. I think we can further agree that some of the assumptions we are making, are at that…. assumptions. I can understand your hesitation regarding whether the system is fully charged or not based upon the lack of proper diagnostic readings under the proper operating conditions. So I’d like to qualify the following statements I’m making are based upon the limited information we both have:

    Regarding your statement:

    “At this point a full set of operational readings must be presented here. First off I am not sold on an undercharge if the total cfm if high. Secondly if the racks are to be addressed for colder air, more registers and their respective throws had better be corrected.
    Reasons:
    1. System doing 15 degree DeltaT. At the same time the return air entering the coil I believe was around 67-68 degrees. Below operating criteria for this equipment and the use of an expansion valve especially if there is no head pressure control….”

    You said that “…if the total CFM is high….”, the system was fully charged, and the system was operating under proper operational conditions (72 degree F R/A by most accounts), then a 15 degree split could be satisfactory. I would agree with that statement 100% but……..

    Based upon the Trane factory literature, this air handler doesn’t have the capacity to produce the 1800 CFM air flow under an outside condition of 69 degrees F and 49% RM(posted above) in order to produce the 15 degree delta T. But again….we are both just making an educational guess without the proper readings. Hopefully the readings are not far off.

    Regarding your statement:

    “Why, if the room and racks are 72-74 is the return air at 67-68. The floor return is seeing a short-circuiting of supply/return air before it can be used for rack cooling. The return should be at or above rack temperature for near 100% efficiency of the system. With cold return air, a lot of air is being wasted and is off-loading the refrigerant circuit.”

    I agree with your option that this particular air handler configuration under these conditions are at best, a suggestion that the installing contractor either did not take the air flow patterns of this room into account before he installed this system or he substituted standard established engineering practices for an inexpensive (I hate the word cheap, even when it apparently applies) system. Then of course, could be he really didn’t understand this concept….now that’s scary! But, again…this is what we have to work with under the present conditions.

    Regarding your statement:

    “If I am not mistaken I read somewhere the room RH is going up during the off cycle. If so where is the humidity coming from? As room temp increases with no additional introduction of water molecules the RH reading should be going down.”

    You read the posts correctly. First I believe there is no substantial additional humidity being introduced into this room at this time. This operating condition where the RH is lower when the compressor is running and then the compressor shuts off and the RH rises even as the room temperature is rising is very normal under the present operating conditions. When you have approximately 120 air changes an hour, such as this system, this situation is in fact expected and has been observed by our company all the time. We deal with systems where the air exchange rate often exceeds the 100 to 300 level. This operating condition is not only extremely common but in fact is fully expected. Specialized experience counts here. But as I’ve stated in my previous posts, I believe this is your area of expertise, as it is mine.

    Regarding your statement:

    “Fix the air flow, fix the refrigerant system, fix the drain if required, put the room in a slight positive and it will work.”

    And commission it…..and I agree with you 100%

    Respectfully Submitted,
    John J. Dalton

    PS: The condensate drains to a condensate pump and is pumped to an out of room receptacle as posted above…..I know…its hard to keep looking back for information….lol.



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