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  1. #1
    Join Date
    Dec 2009
    Posts
    147

    Questions regarding water cooled A/C and high water bills

    Hi there!

    I want your recommendation on reducing a water bill at a factory I service.

    They currently have 45-50 water cooled units totaling approximately 1700 tonnes of cooling. In the summer the equipment runs almost 24/7 I have done done some preliminary figures and estimate they use 5000 GPM!!!!!!!!!

    Most units are Comfort-Aire M# WPC-120-5 and WPC-60-5 (10 tonne 575 V) and (5 tonne 575 V)

    Switching the units to air cooled is NOT an option. Temperatures in the plant range from 70F in the winter to 120F in the summer.

    I maintain and check the water regulating valves each spring and like to set them for 100F condensing.

    I am not against pricing out a closed loop system but I don't have alot of experience in that area. I dont think a cooling tower alone would work because I would like to aim for 60-65F inlet and will have 90-110F outlet.
    IDEAS????

    Any information or help would be appreciated.
    I work in south eastern Ontario to give you an idea of weather conditions.

  2. #2
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Cooling tower!! Don't need 60-65 water.

  3. #3
    Join Date
    Jul 2011
    Location
    Croatia
    Posts
    51
    hi, ginger, i assume you mistakenly changed what you specify as inlet and outlet, cooling tower should lower temperature, not raise it.

    your case seems to be typical case which actually calls for cooling towers. condensing temperature on chiller side should be as low as possible, that will only increase chiller efficiency.

    could you be specific on what do you think is a problem with that?

  4. #4
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,665
    Ontario doesn't get below 70F in winter? Cooling towers is my vote. You're using waste water now?

  5. #5
    Join Date
    Jul 2006
    Location
    Anytown USA
    Posts
    2,062
    Cooling tower and acid clean the condenser bundles..

  6. #6
    Join Date
    Dec 2009
    Posts
    147
    Quote Originally Posted by Drazen View Post
    hi, ginger, i assume you mistakenly changed what you specify as inlet and outlet, cooling tower should lower temperature, not raise it.

    your case seems to be typical case which actually calls for cooling towers. condensing temperature on chiller side should be as low as possible, that will only increase chiller efficiency.

    could you be specific on what do you think is a problem with that?

    I was referring to the inlet and outlet temps of the A/C units.

  7. #7
    Join Date
    Dec 2009
    Posts
    147
    Quote Originally Posted by jtrammel View Post
    Ontario doesn't get below 70F in winter? Cooling towers is my vote. You're using waste water now?
    The temperature in the plant does not go below 70F in the winter. Right now they are using city water. Very expensive!

  8. #8
    Join Date
    Dec 2009
    Posts
    147
    Quote Originally Posted by Tommy knocker View Post
    Cooling tower!! Don't need 60-65 water.
    Optimal temperature for water cooled units is 65F inlet (as per Comfort-Aire specs)

  9. #9
    Join Date
    Dec 2009
    Posts
    147
    Someone asked why I thought a cooling tower was the wrong choice.

    I have very little experience with these so correct me if I am wrong. Wouldnt a cooling tower have to be MASSIVE to reduce the water temperature from 100F to 70F (I would prefer 60-65 however someone else had mentioned that 65F was to cold) especially at 1700 tonnes of cooling inside the plant?

  10. #10
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,724
    Yep sounds like a pump and dump system to me .


    Quote Originally Posted by jtrammel View Post
    Ontario doesn't get below 70F in winter? Cooling towers is my vote. You're using waste water now?

  11. #11
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,724
    45-50 units mostly 10 tons that's 500 tons in my mind where are you getting 1700 tonnes?

    I may be wrong but it's either tons or Kw's not tonnes.

  12. #12
    Join Date
    Mar 2010
    Location
    Morgan Hill Ca.
    Posts
    1,219
    If it were mine, without seeing this set up, I would install a couple small cooling towers. Your math is whack..

    I come up with 1000 GPM at a worse case scenario of 12*F temp split and 500 tons of cooling.

    This would equate to a worst case of two 250 towers... (These are itty bitty)....

    Double check your math against an equipment list and get back to this thread... I'm thinking this job scope would have a stupid fast return on investment.

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  13. #13
    Join Date
    Dec 2009
    Posts
    147
    Quote Originally Posted by GT Jets View Post
    If it were mine, without seeing this set up, I would install a couple small cooling towers. Your math is whack..

    I come up with 1000 GPM at a worse case scenario of 12*F temp split and 500 tons of cooling.

    This would equate to a worst case of two 250 towers... (These are itty bitty)....

    Double check your math against an equipment list and get back to this thread... I'm thinking this job scope would have a stupid fast return on investment.

    GT
    Im using Comfort Aire spec. With 1700 tonnes of cooling when the water is @ 70F the units use 1.35 GPM/ per tonne.
    1.35GPM x 1700 tonnes = 2295 GPM

    You were right to correct me on the GPM. The units use 3 GPM @ and inlet temperature of 85F

    However 2295 GPM is still a heck of alot of water.
    Thanks again for your help.

    Keep in mind this is a fairly large plant with 45 -50 units. Is it even possible to run the supply and return lines that far? I suppose I would just increase the size of the pumps?

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