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  1. #14
    Join Date
    Jun 2008
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    Baltimore,Md
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    27
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    on a CVHF and all chillers there should be no work on refrigerant side meaning charging or recovering refrigerant with out flow thru all vessels with out flow you can freeze and rupture tubes

  2. #15
    Join Date
    Mar 2004
    Location
    ottawa canada
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    Quote Originally Posted by Allen Anders View Post
    on a CVHF and all chillers there should be no work on refrigerant side meaning charging or recovering refrigerant with out flow thru all vessels with out flow you can freeze and rupture tubes
    Sooooo I guess that means I have just been lucky then in the literally hundreds of low pressure machines that I have removed refrigerant and charged without flow ?
    The point Im trying to make is if you understand the refrigeration principle and know how to read a PT chart and a pressure gauge you dont need flow .
    Flow helps you do both recovery and charging when you have it at the right time in the process but to make a blanket statement that you must have flow is incorrect .
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage and yes it still gives me goosebumps
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  3. #16
    Join Date
    Jan 2015
    Location
    Somewhere making cold water
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    178
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    I've always place a gauge on the machine and always have sight glass on my hose to verify no more liquid. Can't cheat physics.

    Sent from my SM-G950U using Tapatalk

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  5. #17
    Join Date
    May 2018
    Location
    San Antonio, TX
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    16
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    Thread Starter
    Really the only way to freeze a tube would be to recover vapor with liquid still in the evap, correct? The boiling off of refrigerant changing to vapor to be recovered would be the heat transfer needed to freeze a tube.

    To drain the water box properly both heads would technically need to be removed to ensure no water is left, right? It’d suck to find out the hard way the chiller wasn’t level.

  6. #18
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
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    1,179
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    Quote Originally Posted by Allen Anders View Post
    on a CVHF and all chillers there should be no work on refrigerant side meaning charging or recovering refrigerant with out flow thru all vessels with out flow you can freeze and rupture tubes
    Push pull the liquid out. No liquid=no refrigeration. When you get all the liquid out and pull vapor only, there’s no refrigeration happening.


    Sent from my iPhone using Tapatalk

  7. #19
    Join Date
    Apr 2017
    Location
    The Deep South
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    217
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    Quote Originally Posted by Iamwildbill View Post
    Really the only way to freeze a tube would be to recover vapor with liquid still in the evap, correct? The boiling off of refrigerant changing to vapor to be recovered would be the heat transfer needed to freeze a tube.
    Theoretically you are correct, but there isn't an adequate volume of refrigerant being boiled off to cause a freeze in most situations. If you push all the refrigerant out of the machine, like others have said, by the time you switch over to vapor, there isn't enough liquid left to boil off to freeze a tube.

    I empty the evap at the drain points due to the ambient conditions in his area. It is stupid hot and stupid humid for most of the year. Tubes sweating during recovery can cause all kinds of headaches when you start pulling a vacuum later.

    Just my $0.02 worth.

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  9. #20
    Join Date
    Apr 2016
    Location
    Maryland
    Posts
    255
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    I may be late to add or missed something ; be sure to connect to the angle valve on the economizer . Also make sure ALL the rust is removed from the flanges .

  10. #21
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    3,301
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    On a CVHE/F not only is the volume of refrigerant boiling off too small to freeze water, it is not even touching the tubes, when recovery is properly done.

    And I definitely agree with being aware of possible condensation. But I see no reason to remove the heads. If flow can't be stopped, due to a leaking isolation valve, isolate as best you can, drain the evaporator, and provide an alternate path for the leak-by (down the drain) without it flowing through the chiller.

  11. #22
    Join Date
    Jul 2003
    Location
    Texas
    Posts
    323
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    When performing push pull, flow is not required. It defeats the purpose of pressurizing machine with any common refrigerant. Once vapor recovery is being perform , water flow is recommended monitoring the freeze point of the particular refrigerant. Ball valve metering is helpful in recovery or charging refrigerant. As for charging , same thing if machine pressure correlates to the freeze point of that refrigerant, water flow is required, however, keep in mind there is always the possibility to have a plugged tube that will not have the ability for expansion of water in a freeze condition that may freeze. That is why tube inspections, cleaning and eddy current is crucial.


    Sent from my iPhone using Tapatalk

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