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  1. #1
    Join Date
    Mar 2004
    Location
    CHICAGO SUBURBS
    Posts
    464

    got some questions for the trane rtu guy's

    Had the 2nd stage compressor fail on a 2 circuit 4 stage I-pak last fall. I will be changing it out in early spring and have a few questions. In a tandum set up, wouldn't the "junk" from a compressor that went tango uniform end up in the other compressor? So I would think both should be replaced. What say's Trane about it? Also, does Trane ship the hermetics out with full oil charge? Should I dump the old compressor/compressors out of oil and measure amount so not to oil log system.I've replaced my share of compressors both herms. and recips., but never in these units. Thanks in advance for the help. It takes a long time to go through all the red tape to get parts where I work so I'm trying to get all ducks in a row early.
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  2. #2
    Join Date
    May 2004
    Location
    new jersey
    Posts
    338
    i have always replaced the tandem set up

  3. #3
    Join Date
    May 2004
    Location
    new jersey
    Posts
    338
    also read the instructions for the oil ring installation.
    and don't assume the phases are going to be correct from the old setup
    to the new.

  4. #4
    Join Date
    Jul 2004
    Location
    Parkersburg WV
    Posts
    343
    I'm assuming your calling a scroll compressor a hermatic. I have changed the oil in the other compressor, being the only time I have changed a compressor in a unit like that it was twin compressors on a circuit although I have seen up to 4 on one circuit.
    Change the oil flush blow it out with Nitrogen, Install new Liquid line F/D and install a suction line filter drier if it was a burn out.
    Come back in a week test for acid and remove or replace the Suction Line drier.
    If your worried about the other compressor Meg it and check the insulation on the windings, I would not inccur the cost of another compressor to the customer if it is not needed.

  5. #5
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,001
    changing out both compressors is certainly not going to hurt anything (other than the check book). i have only done this once. it was after a very nasty burn that we believed took a long time to finally destroy the compressor. we did not think that the other compressor was going to be able to last very long without sustained damaged. i have replaced many compressors due to burns or mechanical damage without replacing both. you will need to replace the oil on the other compressor at a minimum. the new compressors come with oil, however, you will not be able to braze in the oil equalizing tube with the oil in it. so you will need to drain the oil, braze it up and install "clean oil". if you drained the new compressors oil into a bucket, is it still clean? i have always just installed new oil and got rid of the oil that came in new compressor because i could not guarantee that it was clean. this is somewhat wasteful but i never seem to have a clean bucket around. install new suction and liquid line filter/driers. the suction line probably does not have a suction line filter canister, so intall one with isolation valves and upstream and downstream taps to measure pressure drop. after you have finished cleaning the system, remove the suction line filter/driers and install "felts" for minimal pressure drop. you may need to change the oil several times, it wouldn't hurt to change it at least once after the whole thing is cleaned up. whether you replace one or both compressors, you should be prepared to perform the above procedure.

    this is all just to replace the compressors and saying nothing about figuring out why it failed. megger the good compressor. if it says good, it may or may not be good for the long haul (i don't know how the 1st compressor failed). if it says that it is marginal, changing it now would put you money ahead.
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  6. #6
    Join Date
    Feb 2006
    Location
    SouthEastern Virginia
    Posts
    1,075
    Tim,

    I used to work for Trane and have done many of these compressor changeouts. I would not change the other compressor unless it has a problem. When you take out the old compressor, use a hacksaw and cut the pipe as close to the compressor body as you can. Remove the compressor and get your rosebud hot and remove the old compressor fittings from the piping. Be careful with the oil equalizer line when removing. I always drain all oil from both compressors before starting removal. This helps when brazing the oil equalizer line into the new compressor. Use Trane Oil 45 for replacement oil. Clean debris from refrigerant piping after cutting with the hacksaw. The debris will be caught by oil on the walls of the piping so it won't travel far. I would add some acid away to each compressor for insurance and of course new liquid line filter driers. If you have to install a suction drier use a removeable core type and install it in the common suction line. You don't want to leave the cores in the system for any length of time. Make sure and check crankcase heaters cause no cch will kill these badboys.Also log out circuit and find the cause of the failure and correct deficiencies. Good Luck.

  7. #7
    Join Date
    Jan 2007
    Location
    Jacksonville,Fl
    Posts
    123

    What was the failure?

    Quote Originally Posted by tim fox View Post
    Had the 2nd stage compressor fail on a 2 circuit 4 stage I-pak last fall. I will be changing it out in early spring and have a few questions. In a tandum set up, wouldn't the "junk" from a compressor that went tango uniform end up in the other compressor? So I would think both should be replaced. What say's Trane about it? Also, does Trane ship the hermetics out with full oil charge? Should I dump the old compressor/compressors out of oil and measure amount so not to oil log system.I've replaced my share of compressors both herms. and recips., but never in these units. Thanks in advance for the help. It takes a long time to go through all the red tape to get parts where I work so I'm trying to get all ducks in a row early.
    You said "junk", so is this a bunout, or mechanical failure? Do you know the root cause of the failure? If you have a burnout and you intend on waiting 'til spring to replace just one compressor (I wouldn't), recover, change the oil and place a holding charge on your "good" compressor. Then follow normal cleanup procedures (new driers, acid test,repeat). If your failure is mechanical, do the same thing. Here's your problem as I see it, the root cause of your failure has affected both compressors, period, if you know there are no other contributing factors, then you may get lucky by changing just the failed compressor. Take it for what it's worth, but I think the good compressor simply hasn't failed yet.

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