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  1. #14
    Join Date
    Jan 2005
    Posts
    604

    3rd yr apprentice

    [QUOTE=apprentice3yr;2013153]Sorry I thought the 10 10 10 rule of thumb was universal in a way.
    QUOTE]

    If you are an apprentice, you'd be workin' on some old stuff for the 10-10-10 thingy to work.

  2. #15
    yeah Im no longer an appentice though.

  3. #16
    Join Date
    Sep 2007
    Location
    Bay Area California
    Posts
    321
    these high speed carriers can be a handful. i have talked with others in depth about surging issues. does the machine have hot gas? that may be useful...

    also the machine charge may be an issue. with the igv at min open 3-5% should have bubbly flow thru the oil return. this is telling you that the level of the refrigerant in the evap is about right...

    I have multiple chillers that have a problem with surging... constant water flows are important...

    you mentioned 85 deg at full load... i would say try to keep it under 80... as far a low setpoint i would keep it above 70...

    if you have ten deg F appoach on either the condenser or evap you have a mojor problem...

    to back up Randy S. we have all had this problem and it is important to be able to trim your contol settings as every applicaiton can be different...

    good luck...

  4. #17
    Join Date
    Mar 2008
    Posts
    71
    Quote Originally Posted by CaptJackSparrow View Post
    I would also like to see some guidlines to contol tower water temp on Trane VFD chillers with generic BAS as well. I think Tracer Summit has a canned program for this but is there any Trane publised condenser water temps at a given load or is it based on reducing Delta t between chill water and condeser water temp to reduce overall lift at reduced load. What does York base cwt on?
    These machines like colder tower water to maximize afd efficiency. Try a floating tower water set point that equals 5* above the oa enthalpy. this will give you the coldest water possible without wasting energy running tower fans trying to reach a set point it can't acheive. Trane says you need a 5# differential between evap/cond for oil return. Depending on your location, the afd should handle most situations. If needed you can install head pressure control and let the chiller do what it needs. Have seen some non-afd machines use a diff. press transducer accross evap/cond and control the valve or tower fan based on that value.

  5. #18
    Join Date
    Sep 2008
    Location
    Delaware
    Posts
    243
    If you have not done so I would suggest running a log on the chiller at design (normal) operating conditions. We know the things that will cause surge and need to find out which one is the issue. Then start working to resolve it. If you have fouling tubes and are chasing a BAS issuue it may take awhile to isolate the problem. Get the machine running in its basic mode and build on that. K-I-S-S

  6. #19
    Join Date
    Nov 2004
    Location
    North Florida/South Georgia
    Posts
    984

    PIC III?

    slb8101 has the right idea. Let the chiller control the vfd for the tower fan, priod.

    It does a fine job, it does not matter if it is variable or constant speed, the setpoint is configurable as it looks only at the compressor lift.

    As far as I know there is no better way to control a tower fan or a bypass valve than looking at the compressor lift.

    I have several 19XR's & 19XRV's I have set up this way & the operation is flawless.
    All my leon freaked out!

  7. #20
    Join Date
    Nov 2004
    Location
    North Florida/South Georgia
    Posts
    984

    10-10-10 Rule

    Haven't heard that one in a while.

    Most of the machines that would apply to are now license plates.
    All my leon freaked out!

  8. #21
    Join Date
    May 2006
    Location
    N.E. IA
    Posts
    512
    Quote Originally Posted by apprentice3yr View Post
    yeah Im no longer an appentice though.
    Yeah, and when you were an apprentice, you must have had an "Old-Timer" for an instructor?
    "Wheel" mechanics work on "Wheel" chillers

  9. #22
    Join Date
    May 2001
    Location
    Western Wa
    Posts
    1,819
    Thanks, Rob.

    I'm not trying to be a smart ass. I know of a couple 19XRV's that need no less than 68 to not be sinking the coffee can at low load. These were after verifying the charge.

    I also have a 700 ton that needed to go away from the engineered settings on P1 and T1 to avoid low end surging.

    The 19XR's and XRV's are darn good units if you treat 'em right.
    God Bless our Veterans

    God Bless the USA

  10. #23
    What is your cond. approach? Possibly dirty tubes. If you have a wide approach then that will hurt and give you a better chance to surge. Your approach should be between 1-2 degrees but not more than 3 degrees. If the approach is more than 3 degrees then you might want to check your tubes. I live in texas and on a xrv we try to run as cold of cond water we can and on a xr we still try to run 70 degrees. We are you having surge problems? Loaded or unloaded? Go to the chiller and log it when it is having problems. Then tell me what you saw. I need mainly what is on the screen.

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