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Thread: screwy sound

  1. #27
    Join Date
    Sep 2008
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    A land down under
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    309

    Better to replace a check valve than a compressor

    Quote Originally Posted by rover View Post
    RTAA I assume you have more than one compressor on this chiller, do nothing , let it run , if it blows then you know it was a screwy sound.
    The primary function of the check valve is to stop the reversal of flow causing the rotors to free wheel in reverse when the gas re-expands after a compressor shutdown in order to prevent damage from the thrust reversal.

    A second but equeally important function of the check valve is to prevent refrigerant condensing and draining into the compressor during an off cycle. Refrigerant will migrate to the coldest area and in the liquid state is influenced by gravity.

    In applications like the RTAA where the compressor is below the condenser, if the check valve is not sealing refrigerant could fill the compressor during the off cycle and cause problems ranging from high motor starting current to compressor damage from the hydrostatic forces developed by the screws pumping 100% liquid.


    My advice is if the check valve is leaking change it out or you will be asking the customer to pay for a compressor replacement in the immediate future.

  2. #28
    Join Date
    Jan 2009
    Location
    Not in Iran
    Posts
    1,093

    Talking and the rest of the story.,

    anyways ., ordered the chcek valve, the following day i called to check in on something else., talked to same guy and he asked me if c valve was on top of compressor., said no ., he faxed over spec sheet., he was going to order me oil system c valve,
    got right KIT coming., (kit02308)
    support c valve,
    o ring
    washer c valve.,
    retainer c valve
    seal c valve.,
    and this should do the trick.,,..,
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

  3. #29
    Join Date
    Jan 2009
    Location
    Not in Iran
    Posts
    1,093

    am i wrong?

    am i wrong to say and do this?.,,,

    when accessing the discharge end of the compressor to change check valve, piston and rings that the discharge line will need to be unbolted and cut downstream of the discharge line shut off valve,and moved out of the way., that is the only way i see able to have any room to work on one of these areas.,.,
    trane screw
    rtaa
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

  4. #30
    Join Date
    Jul 2007
    Location
    The Hot South
    Posts
    1,317
    You should be able do bend it out of the way.

  5. #31
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Buy the suction valve gasket. Isoltate the compressor. Unbolt the suction and discharge lines. Slide the compressor on the base rail enough to clear the discharge line. If you cut the line you will still have a hard time putting the coupling on unless you can find a slip coupling.

  6. #32
    Join Date
    Oct 2004
    Location
    Metro ATL
    Posts
    454
    Quote Originally Posted by Phisher View Post
    There should be a distinct sound when the check closes. Put the circuit into a manual pump down. If the check valve is holding then you should maintain a pressure difference between the condenser and evaporator. Have you checked the oil solenod on the oil supply line to make sure it closes when the compressor cuts off? I'm not sure if that can cause the compressor to back spin or not but it might be something to check. Any ideas on that?
    If the oil line solenoid did not shut the chiller should throw a diagnostic that it did not see the oil pressure differential trip the switch on shutdown. Can't remember the specific diagnostic off the top of my head.

  7. #33
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
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    861
    Quote Originally Posted by jemawalton View Post
    If the oil line solenoid did not shut the chiller should throw a diagnostic that it did not see the oil pressure differential trip the switch on shutdown. Can't remember the specific diagnostic off the top of my head.
    Does an rtaa 140 have an oil line solenoid or master solenoid? We don't take care of any rtaa's above 125 and they don't. I know the rtha's, rthb's and rthc's oh and d's have them.

  8. #34
    Join Date
    Jul 2007
    Location
    The Hot South
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    1,317
    Quote Originally Posted by cperk View Post
    Does an rtaa 140 have an oil line solenoid or master solenoid? We don't take care of any rtaa's above 125 and they don't. I know the rtha's, rthb's and rthc's oh and d's have them.
    The RTAA's above 130 tons have an oil line solonoid on each compressor. When the compressor shuts down, the UCM de-energizes the oil solonoid before the compressor shuts down to verify that the oil differential switch trips within a certain amount of time. If it doesn't, the UCM calls out an oil safety fault.

  9. #35
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
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    861
    Quote Originally Posted by R123 View Post
    The RTAA's above 130 tons have an oil line solonoid on each compressor. When the compressor shuts down, the UCM de-energizes the oil solonoid before the compressor shuts down to verify that the oil differential switch trips within a certain amount of time. If it doesn't, the UCM calls out an oil safety fault.
    Thanks, CHCL2CF3,R123

  10. #36
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    4,388
    there's not much room, but it can be done...just takes skinny fingers to get the gasket areas clean.

    cperk is funny...2,2 dichloro-1,1,1-trifluoroethane!
    When I am late for work, I usually make up for it by leaving early.

  11. #37
    Join Date
    Jan 2009
    Location
    Not in Iran
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    1,093
    suction gasket all day
    thanks
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

  12. #38
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Hey mlkwal1 I'll be down your way the 1st of Dec for a long weekend.

  13. #39
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    Jan 2009
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    Let me know when u get in town
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

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