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  1. #131
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    my hvac guy just called....he told me to drop the temp to 70 and turn the fan to on instead of auto....he also said he wants to take the calculated numbers during a hot do, not on a day like today where the temp is 62 and was 55 this morning

  2. #132
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    It'll be OK....lets keep working on the problem.

    Dear Serverroomcooling,

    Like I said before. Don’t give up on this ship quiet yet. I know….yes….I know, we can get the system working better than it is now. We just need information and we can help you commission this system to its maximum potential. Have two ands and a brain ready to work….lol.

    The vent intake to the room and the vent outlet from the top of the spot cooler to the room was the return air from the room and the chilled air to cool the room I’m assuming. What about the condensing air in and out of the cooler, you should have had two hoses. One hose was air being sucked from somewhere other than the room and another hose to discharge the hot condensing air out of the room. Where were these two hoses?

    Respectfully Submitted,
    John J. Dalton

    PS: We all get frustrated…but after we clear our heads, we’ll put them together and solve this problem!.


  3. #133
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Serverroomcooling,

    Would it be possible for you to get a little information for me this afternoon?

    When the compressor cycles on and starts cooling, after it has ran for at least five minutes, could you get the return air grill temperature and then the supply air temperature(the air temperature coming from any one of the supply registers in the ceiling). This would give us a preliminary CFM/ton measurement which is extremely important in diagnosing and preventing freeze ups.

    Respectfully Submitted,
    John J. Dalton

    PS: Understand the evaportive fan is now running all the time.

  4. #134
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    there are no hoses...this is truly a portable spot cooler, roll it in, pop a ceiling tile up, put in the vent cover, attach the duct, and the hot air gets blown into the ceiling. Air intake is from the room, It sucks in from one of the sides.

    I think keeping the fan on at all times will help the situation a bit....I'm going into the room for 45 minutes to monitor the cycles

  5. #135
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Serverroomcooling,

    “..my hvac guy just called....he told me to drop the temp to 70 and turn the fan to on instead of auto....he also said he wants to take the calculated numbers during a hot do, not on a day like today where the temp is 62 and was 55 this morning…”

    He probably is busy at this time, But……..

    This system has several potential problems and one of them lies in the ability of this system to continue to cool in this cooler or even cold weather. These reading need to be taken when it’s hot outside, but they just as equally needs to be taken when its cool or even cold outside. Readings taken early in the morning when the temperature is 55 degrees F would be VERY important in ascertaining weather a condensing fan capacity control is needed to maintain system capacity and the PREVENT system freezing.

    Respectfully Submitted,
    John J. Dalton

  6. #136
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Serverroomcooling,

    “…I think keeping the fan on at all times will help the situation a bit....I'm going into the room for 45 minutes to monitor the cycles….”

    Yes…this will help. Glad to see you’re monitoring……Can you get the outside temperature as well?

    Did I see in one of your previous posts that you have the ability to measure what the humidity is inside the server room? If so, can you post that with the return and supply air readings to determine a preliminary CFM/ton number?

    Respectfully Submitted,
    John J. Dalton


  7. #137
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Serverroomcooling,

    “…there are no hoses...this is truly a portable spot cooler, roll it in, pop a ceiling tile up, put in the vent cover, attach the duct, and the hot air gets blown into the ceiling. Air intake is from the room, It sucks in from one of the sides….”

    That’s bad! The cool air from your server room is being sucked into the condensing part of the spot cooler and then being ducted to the space above the ceiling (that’s the correct ducting for the air out). But the suction on the spot cooler will create a highly negative pressure inside the server room and cause your new system to suck unconditioned, unfiltered, and at times un-cooled air from the surrounding areas. The proper use of these spot coolers in a server room such as yours is the following:

    The spot cooler will have two hoses on it, the first will be the makeup air for the condensing unit and the second will be the hot air discharge from the condensing unit. BOTH hoses MUST be installed outside of the server room for proper operation. It will work without the second hose, but less efficiently, especially during times when the building HVAC central plant is not running (i.e. the times you need it the most).

    More to follow.

    Respectfully Submitted,
    John J. Dalton

  8. #138
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    the guys just left, here's what they told me. They said that they need to come back on a hot day to take their caalibrations, b/c once they grab what they need and put in the proper amount of freon, they say we won't need to worry about the cold days b/c the freon will remain at a safe pressure. He didn't add anything today b/c the gas will expand and could blow the compressor when the temp gets hotter.

    I asked about the short cycle tstat they didn't think I needed it once the system gets the proper amount of freon in it.

    I guess if I decide to purchase a spot cooler it will be different than the one I have here now. I'll get the one you spoke about, it is probably just a different model.

    but, maybe I won't need one, the guys set my tstat down to 65 and said the freeze had nothing to do with the temp it was set at. They did give me a reason, but I didn't quite follow. He had the gauges with him and still seems confident that the system will be ok....I'll continue to monitor, as this seems to be my new full time job :-)

    I'll post my cylce times as soon as I have them with the tstat set to 65 and outside temp of 67 (now)

  9. #139
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Still here

    Dear Serverroomcooling,

    My comments as follows:

    “…the guys just left, here's what they told me. They said that they need to come back on a hot day to take their caalibrations, b/c once they grab what they need and put in the proper amount of freon, they say we won't need to worry about the cold days b/c the freon will remain at a safe pressure. He didn't add anything today b/c the gas will expand and could blow the compressor when the temp gets hotter.”

    It true that its much easier to charge a system when its hot outside, but……like I said its much earlier, not impossible. The proper thing would have been to properly charge the system now….and then on a hot day, recheck the charge if they are concerned about it. Next, “…when the system is properly charged…”…How long must we wait to properly charge the system, till the weather gets hot, how long will that be????.

    And when the system is charged properly, you won’t have to worry about a cold….I just still don’t believe that for a moment!

    He didn’t add today because it could blow the compressor…….yes it could, if he added way too much.

    I asked about the short cycle tstat they didn't think I needed it once the system gets the proper amount of freon in it.

    What???? Air conditioning isn’t rocket science, I think you should understand the following:

    The cycle rate on the compressor will be a function of one thing and one thing OLNY!
    It is a function of how fast your server room rises in temperature after the compressor cycles off. Notice I said “AFTER” the compressor cycles off. It DOS NOT depend on the HVAC system at all! So whether the HVAC system is charged properly or not, has nothing to do with the rise of temperature in your server room once the compressor is cycled off.

    Some items that WILL affect the cycle rate will be how much computer equipment you have running, how hot it is outside, is the server room lights on, and whether the building air is on or off.

    Worst case of short cycling will be under the following conditions:

    You have the most computer equipment running.
    You have the server room lights on.
    The outside temperature is hot..
    The building air has been off for some time.

    The best case for short cycling will be under the following conditions:

    You have the least of computer equipment running.
    You have the server room lights off.
    The outside temperature is cold.
    The building air is on.

    In short, as the heat load inside the server room increases, so will the cycle rate of the compressor, and inversely, as the heat load decreases inside the server room, so will the cycle rate of the compressor.

    Do you see the system’s refrigerant charge, efficentency, or capacity anywhere in the above statement? You don’t because it has nothing whatsoever to do with the cycle rate; therefore your HVAC contractor is grossly incorrect in his statement.

    “…I guess if I decide to purchase a spot cooler it will be different than the one I have here now. I'll get the one you spoke about, it is probably just a different model.”

    All spot coolers are basically the same, its how they’re installed that’s the key. Your old spot coolers would probably be fine, if installed correctly. But let’s hold off on the spot cooler talk until the system is properly commissioned.

    “…but, maybe I won't need one, the guys set my tstat down to 65 and said the freeze had nothing to do with the temp it was set at. They did give me a reason, but I didn't quite follow. He had the gauges with him and still seems confident that the system will be ok...”

    Let’s see…..they came, they reset the thermostat to its original setting when it iced up before, they did nothing else, they offered an explanation that didn’t make sense to you, and they left. Gee, do you think the ice up problem has been resolved or do you think you’ll be back after hours and get some more experience defrosting the system after an ice up?

    “…I'll continue to monitor, as this seems to be my new full time job :-) I'll post my cylce times as soon as I have them with the tstat set to 65 and outside temp of 67 (now)…”

    I’ll be waiting. Could you please include the return and supply temperatures along with the inside humidity if possible?

    And yes….we WILL solve this problem!

    Respectfully Submitted,
    John J. Dalton



  10. #140
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Leaving, but will be back in one hour.

    Dear Serverroomcooling,

    I’m leaving the office early this afternoon, but I’ll contact you when I get home…..waiting on those cycle rates and temperatures in and out of the HVAC system along with the indoor humidity if possible. I’ll stay in touch.

    Respectfully Submitted,
    John J. Dalton

    PS: Keep smiling, you’re getting a great education in air conditioning along this rough road! Just think of how easier your next evaluation of proposed A/C will be. This is still salvageable. Honestly!

    PSS: See you in about 45 – 60 minutes.

  11. #141
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    John, I wish you were down here in Florida!!!

    I'm not sure what to expect from what was done, I think they did make some changes at the compressor, I did hear bumps and clanks coming from the main lines, not sure what they were, maybe the pressures were off and he did adjust them....as far as whom to believe.....I am with you on all this, I wish I had a better grasp on this subject so I could really argue with the guys. They were techs, not the owner of the company. Bottom line is that if I get to the point where I feel they won't be able to help me, I will have to call in another company to give me peace of mind. One or two more ice overs and I might be able to make that assumption (if that's too harsh, let me know).

    I'm going to gather the cycle info and air retun temps with the air handler fan always on (which was an oversight by my guy)

    right now the tstat is set at 65, which is lower than it was this weekend. They swear that I can put the tstat down to what ever I want without worrying....we will see about that!! The rack temp is 74 and still seems to be going down!!! The UPs system is running at an iternal temp of 97....I think that is awesome....I would sleep very sound at night if it stays like this!!

  12. #142
    Join Date
    Nov 2004
    Location
    Hollywood, FL
    Posts
    365
    with the tstat set to 65 and outside temp of 69 with outside humidity of 57% (florecent lights on inside the server room, they are alwys off unless someone is in there)

    off cycle is 3.5 minutes on cycle is 9 minutes

    3:20 63 off
    3:21 63.3
    3:22 64.9
    3:23 66
    3:24 67 on
    3:25 66.9
    3:26 66
    3:27 64.9
    3:28 64.2 56%
    3:29 63.7 54%
    3:30 63.3 52%
    3:31 62.8 50%
    3:32 62.8 off 51%
    3:32 63.3 52%
    3:33 64.2 53%
    3:34 65.5 55%
    3:35 66.9 64%
    3:35 67.3 on 66%

    the humidty inside the room fluctuates a lot. My equipment can run between 10% and 90%. The two thermometers read pretty steady at 68% with 55-60% humidity during the cycles.

    I am noticing that the room is heating up mich differently with the fan on, it stays comfortable, heat spots seem to be much less

    how do I calculate the cfm again?? I forgot, and it's tough to find in the post


  13. #143
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560

    Back home now

    Dear Serveroomcooling,

    My comments:

    "...One or two more ice overs and I might be able to make that assumption (if that's too harsh, let me know). "

    Let's not jump off our horse in midstream quiet yest. We'll give your HVAC contractor the benifit of doubt for the moment.

    "''They swear that I can put the tstat down to what ever I want without worrying....we will see about that!"

    Statements like that scare me. The lower you set the thermostat, the more of a chance you take in iceing up the system, properly charged or not!

    Respectfully Submitted,
    John J. Dalton

    PS: Wish I were there as well to take the readings and comission the system for you, but thats OK, we'll get though this!

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