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  1. #1
    Join Date
    Jan 2001
    Posts
    758

    calculating tonnage through chilled coil

    is there a way with flow,splits to calclate tonnage of a chilled water coil

  2. #2
    Join Date
    Oct 2004
    Location
    Metro ATL
    Posts
    454
    Yes, you will need entering water temp, leaving water temp and flow rate and you can do it.

    http://www.advantageengineering.com/...tageFYI288.php

  3. #3
    Join Date
    Nov 2007
    Posts
    388
    You can calc cooling capacity either using the water or air side flow and temperatures. Water is method is the simplest:

    GPM*500*H20 Delta T = BTU/H Note: The 500 constant assumes straight water (no glycol)

    For air you'll need to measure airflow and take wet bulb and dry bulb temperature readings across the coil. Find the resulting entering and leaving enthalpy for each using the psychometric calculator located here http://www.trane.com/commercial/soft...eb_toolbox.asp

    CFM*4.45*Delta enthalphy = BTU/h

    There you have it....Git 'er dun!
    Never let weakness convince you that you lack strength.

  4. #4
    Join Date
    Jan 2001
    Posts
    758
    there is glycol in the system. to get gpm divide pressure difference by design pressure difference. how do i get dsign pressure delta

  5. #5
    Join Date
    May 2008
    Location
    Central Pennsylvania
    Posts
    441
    The design gpm is usually documented on the equipment data page of the job drawing or you'll have to go back to the coil manufacture. If you figure out the specific gravity of your glycol mixture, there is another formula to correct the difference between water and glycol, using the previously listed formula. (Hope that makes sense) I can try and find that correction factor formula tomorrow, but the water formula gets you pretty close, even with a 33% prop. glycol mixture.

  6. #6
    Join Date
    Mar 2009
    Location
    Illinois
    Posts
    8
    Quote Originally Posted by hvac17011 View Post
    is there a way with flow,splits to calclate tonnage of a chilled water coil
    This is a useful site. http://wea-inc.com/hvac_calc.htm it has helped me in the past.

  7. #7
    Join Date
    Nov 2008
    Location
    NE Texas & Houston
    Posts
    57
    If you can get a curve for that coil from the manufacturer you can use the water pressure drop across the coil to determine GPM flow and read capacity.

    When you have that, calculate 1 btu to lower the temp of one pound of water 1 degree. Convert pounds of water to gallons.

  8. #8
    Join Date
    Mar 2009
    Location
    medellin colombia
    Posts
    6
    ok, you do get GPM with the drop water in vs out pressure , delta p is view at chart of fan coil desing factory and view gpm and ok FLYFARN REASON

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