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Thread: Humidity

  1. #1
    Join Date
    Aug 2006
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    Humidity

    Good Morning

    I manage an offiste colocation data center for my company. And I'm having problems with low humidity, on avg the 5 Crac's are running around 35% and 75F. How can I raise the humidity while not interfering with the temp. by the way, this center is located in Boston.

  2. #2
    Join Date
    Feb 2007
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    tampa fl
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    7

    to cool

    Quote Originally Posted by bodu View Post
    Good Morning

    I manage an offiste colocation data center for my company. And I'm having problems with low humidity, on avg the 5 Crac's are running around 35% and 75F. How can I raise the humidity while not interfering with the temp. by the way, this center is located in Boston.
    First, fans on 24 - 7 Also do these units have humidfers
    can maint wash floors more often?

  3. #3
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    Aug 2006
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    Thx, fans are on 24x7 I'm told. Not sre how often floors are cleaned. Thx, anymore suggestions

  4. #4
    Join Date
    Feb 2004
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    80
    Put fans on highest speed possible and add a humidifier. The slower the fan the more humidity the evap will take out of the air. So a faster fan will equal less on time.

  5. #5
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    Aug 2006
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    Thx, fans are on 24x7 I'm told. Not sre how often floors are cleaned. Thx, anymore suggestions

  6. #6
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    Aug 2003
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    Fort Worth, TX
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    Raising the blower speed may also raise the temperature in the space if the evap ends up being overwhelmed with air and heat load. In order to run an evap above dew point (running a coil at or below dew point is what pulls moisture out of the air) but maintain design space temp, the equipment must have the sensible heat capacity to do so.

    If this is a computer room it may need humidification added to keep humidity above 35%. Liebert has air handlers with built in steam humidification, or you might take a look at options over at www.humidity.com (Nortec). We have a Nortec electric steam humidifier for one of our cold storage areas. Other than swapping out the steam generator bottle about every three months (which saves the awful mess of cleaning a steam humidifier), it works fine. It can be operated by proportional control so you do not overhumidify the space.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  7. #7
    Join Date
    Nov 2005
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    Shreveport, Louisiana
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    Quote Originally Posted by shophound View Post
    Raising the blower speed may also raise the temperature in the space if the evap ends up being overwhelmed with air and heat load. In order to run an evap above dew point (running a coil at or below dew point is what pulls moisture out of the air) but maintain design space temp, the equipment must have the sensible heat capacity to do so.

    If this is a computer room it may need humidification added to keep humidity above 35%. Liebert has air handlers with built in steam humidification, or you might take a look at options over at www.humidity.com (Nortec). We have a Nortec electric steam humidifier for one of our cold storage areas. Other than swapping out the steam generator bottle about every three months (which saves the awful mess of cleaning a steam humidifier), it works fine. It can be operated by proportional control so you do not overhumidify the space.
    I have a lot of Sultz units that have Nortec humidifeirs and they are the easiset to work on and are great. I would recommend them to anyone.

  8. #8
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    Sep 2006
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    Ma.
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    Are they Liebert units? Are they being properly maintained?
    If they aren't you may not have all the units’ humidification running!
    What are the set points on the humidification units? Are they set for 35% or set for the usual 45%. I mainly service Data centers in and around Boston if you need a quality company to service your equipment let me know and I can get you in touch with our sales staff to set up something. Email is in my profile! Depending on the unit and type of humidification preventative maintenance will most likely solve your problems. I agree that steam is very nice, nortec is good and apart from the infrared Liebert does have their own steam canisters, Stulz units however are junk in my opinion and I wouldn't recommend them to anyone I dislike.


  9. #9
    Join Date
    May 2004
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    Los Angeles, CA
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    Dear Bodu,

    Based on the fact that the data center is located in Boston, good engineering practice would dictate that the HVAC system was designed and installed with some form of humidification. With that said, the fact that the indoor humidly has dropped to 35% would suggest one of two separate problems, either the HVAC system(s) where installed without humidification in mind, or the existing humidification system(s) require either repair or P/M. The solution would then simply be to either install a new humidification system for one that is lacking, or repair and/or P/M the existing one(s).


    At this time I would like to correct a couple of misstated posts on this thread in regards to data rooms and humidification systems:

    Chr358:
    “The slower the fan the more humidity the evap will take out of the air. So a faster fan will equal less on time.”

    Although lower airflow per ton will increase the de-humidification capacity of the refrigeration system, increasing the airflow per ton will decrease the de-humidification capacity of the refrigeration system NOT because of “less on time” as stated, but because of an increase in the sensible/latent ratio of the refrigeration system in respect to its evaporative airflow.


    Shophound:
    “Raising the blower speed may also raise the temperature in the space if the evap ends up being overwhelmed with air and heat load. In order to run an evap above dew point (running a coil at or below dew point is what pulls moisture out of the air) but maintain design space temp, the equipment must have the sensible heat capacity to do so…”

    Increasing the evaporative airflow will simply increase the sensible/latent system capacity ratio which will not only NOT hurt the above project, but WILL in fact make the HVAC system more energy efficient while increasing the overall sensible heat capacity of the system. The sensible heat load of the above data room most provably accounts for at least 95% - 98% of the overall sensible/latent heat load of the entire room, therefore again increasing the airflow per ton will only improve the overall sensible heat capacity of this system. Now, we would not want to increase the airflow thru the evaporator so much as to remove its ability to de-humidify when the system (outside conditions) calls for it.

    Shophound, I like the Nortec, as well as the Armstrong, electric steam generators myself, only we use the cleanable tanks since we have to replace/clean the tanks every 3 to 4 weeks at our locations here in the Los Angeles, CA area.

    Respectfully Submitted,
    John J. Dalton

  10. #10
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    Apr 2003
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    the Great Pacific Northwest
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    How well is the room sealed ? Is there any fresh air being introduced to the room? Data rooms need to have a very tight construction with vapor barriers and penetration sealing as well as humidifiers and controls to maintain proper humidity control.

  11. #11
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    May 2004
    Location
    Los Angeles, CA
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    Backup everything .....except the HVAC system....ya, what a joke!

    Dear Hvac-tech-lane,

    There’s no doubt about it, humidity control from both the de-humidification and the humidification standpoint, is much harder to measure, control, provide P/M, and work on, in relationship to it’s sister component, temperature. All server and date rooms need some sort of humidity control (both up and down) for the equipment in the room to be totally protected.

    It’s hilarious how much redundancy the end-users, architects, and mechanical engineers build into server and data rooms in the form of fire suppression systems, emergency generator systems, backup server and data systems, emergency lighting systems, and their countless “Emergency Operating Manuals” while at the same time having almost no budget for any temperature or humidity control of their precious rooms………what a joke!

    Sorry….just venting………I’m back……happy face and all!

    Respectfully Submitted,
    John J. Dalton CM

  12. #12
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    Quote Originally Posted by john dalton View Post



    Shophound:
    “Raising the blower speed may also raise the temperature in the space if the evap ends up being overwhelmed with air and heat load. In order to run an evap above dew point (running a coil at or below dew point is what pulls moisture out of the air) but maintain design space temp, the equipment must have the sensible heat capacity to do so…”

    Increasing the evaporative airflow will simply increase the sensible/latent system capacity ratio which will not only NOT hurt the above project, but WILL in fact make the HVAC system more energy efficient while increasing the overall sensible heat capacity of the system. The sensible heat load of the above data room most provably accounts for at least 95% - 98% of the overall sensible/latent heat load of the entire room, therefore again increasing the airflow per ton will only improve the overall sensible heat capacity of this system. Now, we would not want to increase the airflow thru the evaporator so much as to remove its ability to de-humidify when the system (outside conditions) calls for it.

    Shophound, I like the Nortec, as well as the Armstrong, electric steam generators myself, only we use the cleanable tanks since we have to replace/clean the tanks every 3 to 4 weeks at our locations here in the Los Angeles, CA area.

    Respectfully Submitted,
    John J. Dalton
    I see your point, Mr. Dalton. I was focusing on a specific room temperature setpoint, and that running the blower quicker might not allow enough air contact time with coil (increasing bypass factor) and thereby the heat load of the computer room might run away from the system's ability to remove it. I can see how upping the cfm/ton would increase sensible over latent, being that the apparatus (coil) temp would rise (higher dewpoint, less dehumidification) as it picks up more heat via increased sensible load.

    My question would be is there a point of no return where if the blower speed is increased too much, there is actually a sensible capacity loss, being that the bypass factor has become too great as well as the imposed heat load on the coil compared to the compressor's ability to move refer through the loop?
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

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