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  1. #1
    Join Date
    Sep 2004
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    522
    Can someone tell me a formula for finding actual tonnage output on a chiller.

  2. #2
    Join Date
    Jun 2003
    Location
    in a tree looking in your window
    Posts
    1,162
    This is is what I use, screwed it up the first time.

    Delta T x gpm divided by 24 = tons

    Tons x 24 divided by delta t = gpm



    [Edited by chillrdude on 04-05-2006 at 12:16 AM]
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  3. #3
    Join Date
    Feb 2006
    Posts
    203
    500 x gpm x delta T
    refrigeration workers of Ontario

  4. #4
    Join Date
    Jan 2004
    Posts
    1,174
    close but it is GPM x 500 x deltatemp divided by 12000BTU's

  5. #5
    Join Date
    Sep 2004
    Posts
    522
    thanks journey man. My head was starting to hurt.Duhhh!!!!

  6. #6
    Join Date
    Jan 2005
    Location
    SE Florida
    Posts
    220
    how do you solve for gpm

  7. #7
    Join Date
    Sep 2004
    Posts
    522
    Manufacturer should have curve chart for delta P that shows GPM.

  8. #8
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    You can't solve for gpm unless you know the BTUH and you can't solve for BTUH without an accurate gpm. The most accurate way of getting gpm is using a flow meter which involves cutting pipe and installing the meter.


  9. #9
    Join Date
    Apr 2002
    Posts
    11,808
    should be in ball park using pressure drop across barrel

  10. #10
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Specific heat of water is essentially 1 Btu/lb-F
    There are about 8.337 lb water (60F)/gal
    8.337 * 1 = 8.337 Btu/gal-F
    There are 12,000 Btu/h or 200 Btu/min in a ton
    200 Btu/min-ton / 8.337 Btu/gal-F = 23.99 gpm-F / ton

    So multiply gpm by delta T and divide by 23.99 and you will get tons!

    [Edited by Andy Schoen on 04-05-2006 at 12:04 AM]

  11. #11
    Join Date
    Feb 2004
    Posts
    534
    what if you have Glycol in system? will your formula change by adding glycol?

  12. #12
    Join Date
    Jan 2005
    Posts
    604
    Yep, it'll change.

  13. #13
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Originally posted by service guy
    what if you have Glycol in system? will your formula change by adding glycol?
    I see one source http://www.engineeringtoolbox.com/et...col-d_146.html which states specific heat of a 50/50 water ethylene glycol mix reduces specific heat to about 0.78 Btu/lb-F (below 32F) and has a specific gravity of 1.1. So we can figure:

    8.337 * 1.1 * 0.78 = 7.153 Btu/gal-F
    There are 12,000 Btu/h or 200 Btu/min in a ton
    200 Btu/min-ton / 7.153 Btu/gal-F = 27.96 gpm-F / ton
    So in this case, multiply gpm by delta T and divide by 28 to get tons.

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