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Thread: Trane RTA

  1. #1
    Join Date
    May 2007
    Location
    Michigan
    Posts
    311

    Hmm Trane RTA

    Hey all
    have a trane RTA Chiller - twin screw. CKT 1 is tripping on low evap temp.
    CKT 2 runs all day but is only pumping out 50 deg water - by the time it is reaching the secondary it is 58 deg. Could this be a plugged strainer on the primary if so why is the secondary so warm and why is this thing running if it is plugged. thanks guys

  2. #2
    Join Date
    Mar 2007
    Posts
    3,103
    The easiest thing to do in your case would be to verify the water flow through the evaporator. There is a chart in the IOM that shows what your pressure drop should be at various flow rates. Sometimes you can find the design gpm written inside the control panel or on a log sheet. If you verify the flow with some reliable gauges, it's ok, and you're not shorting the loop somewhere, then you may have a charge and/or load/unload issue.

    Need more info.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  3. #3
    Join Date
    May 2007
    Location
    Michigan
    Posts
    311

    Trane RTA

    Just wanted to throw it out there - if I had a problem with flow wouldnt my liquid supply lines be cooler - currently at 51 deg with CKT one running only CKT one. Hard to believe the strainers would be plugged?

  4. #4
    Join Date
    Apr 2006
    Location
    Motel 6.5
    Posts
    148
    Got any oily parts? If your flow is good, start looking for leaks. Check the suction valve on the evap. first.

  5. #5
    Join Date
    May 2007
    Location
    Michigan
    Posts
    311

    Heya Guy

    Man - watchin this thing on a Sat night - vacation weekend wow.
    We could not get a handle on the RTA so we had to get help from JCI - going on our 4th guy tomorrow.
    We got two HVACR guys for 21 schools - yay. My boss calls in JCI - what a mistake. Guy says it is flow - the other guy said yah maybe a small leak lets put some juice in her and see our approach - last guy says lets pull the refrigerant and weigh it to see if it is as much as the data plate says, we had 12 lbs more.
    Going in the morning to see if the inlet to the pump is plugged or the y strainer is plugged to take care of our end. I think it is something dumb like the loader hangin up or something.

  6. #6
    Join Date
    Jun 2009
    Location
    Florida
    Posts
    540
    Verify the flow through the cooler barrel like Rob said, then if flows are ok, the most likely culprit is low charge. If the charge is good, it may be starting loaded with the slide valve piston stuck or loading too fast due to a worn seal on the piston. Monitor the RLA from startup through the first minute or until it trips. It should start at around 45 to 50% RLA (after transition if not a X-line starter) and slowly rise a couple of percentage points with each pulse of the load solenoid. If it starts at 70% or higher, your slide valve is stuck and if it starts low and jumps several percent with each solenoid pulse, then the seal rings are worn. Check those things out and report back in. Good luck...CW
    Low Pressure Forever!

    If you know heavy metal, you can work anywhere-Dave Andreson

    Anchors Aweigh my boys, Anchors Aweigh!
    Farewell to foreign shores, We sail at break of day. Through our last night on shore, Drink to the foam. Until we meet once more. Here's wishing you a happy voyage home!

  7. #7
    Join Date
    Jan 2010
    Location
    Southeast US
    Posts
    4

    Cool

    Go to P4 menu and check cut out temperature. You said charge was actually 12 LBS more? If flow was issue wouldn't circuit 2 be having same prob? How bout sat evap temp sensor being out of calibration? EXV? Good luck !

  8. #8
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    4,258
    Quote Originally Posted by Chris Boyer View Post
    Go to P4 menu and check cut out temperature. You said charge was actually 12 LBS more? If flow was issue wouldn't circuit 2 be having same prob? How bout sat evap temp sensor being out of calibration? EXV? Good luck !
    P4?!! we don't even know what he has...UCP1, UCP2, CH530? i agree with you on sensor accuracy questions. like berger said...need more info.
    my 1st time jumping out of a plane...http://youtu.be/Kv38G0MHsGo

  9. #9
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    873

    Long Distance Operator, Information Please

    RTA doesn't give us too much information, Full model # + serial # and a good basic running log as is. If circuit 1 trips on low evaporator what does the evaporator entering refrigerant temp sensor read and the suction temp sensor. P-4 low refrigerant cut-out is 22*F, low water is 35*F and either one would lock out the entire chiller not just one circuit. Check your delta P's across the flow chart in the IOM. Also most, not all RTA's are set for 8-12*F delta T (differential of entering and leaving water) so if your setpoint is say 45*F and you are one circuit down putting out 50*F leaving water, it maybe doing all it can do-GEO

  10. #10
    Join Date
    Jun 2009
    Location
    Florida
    Posts
    540
    Quote Originally Posted by ga1279 View Post
    RTA doesn't give us too much information, Full model # + serial # and a good basic running log as is. If circuit 1 trips on low evaporator what does the evaporator entering refrigerant temp sensor read and the suction temp sensor. P-4 low refrigerant cut-out is 22*F, low water is 35*F and either one would lock out the entire chiller not just one circuit. Check your delta P's across the flow chart in the IOM. Also most, not all RTA's are set for 8-12*F delta T (differential of entering and leaving water) so if your setpoint is say 45*F and you are one circuit down putting out 50*F leaving water, it maybe doing all it can do-GEO
    Low ref. temp is a CMR diagnostic, not a MMR.
    Low Pressure Forever!

    If you know heavy metal, you can work anywhere-Dave Andreson

    Anchors Aweigh my boys, Anchors Aweigh!
    Farewell to foreign shores, We sail at break of day. Through our last night on shore, Drink to the foam. Until we meet once more. Here's wishing you a happy voyage home!

  11. #11
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,297
    You guys are getting way ahead of yourselfs. We don't even know what type of RTAA this is. Is this a 70 to 125 ton RTAA with GP compressors and clear language display? Or is this a 130 to 400 ton RTAA with intermediate compressors and UCP 1 style controls with blue LED display? It makes a HUGE difference. Please post Model and Serial number with complete log.

  12. #12

    RTA-200 rattling noise inside unit

    We may have a suspected loose or failed tube bracket/support. How huge a job is this to repair/replace.

  13. #13
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,297
    Quote Originally Posted by dkas View Post
    We may have a suspected loose or failed tube bracket/support. How huge a job is this to repair/replace.
    What?

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