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  1. #1
    Join Date
    May 2007
    Posts
    41

    Trane Precedent TSC120 Evap/Orifice Restriction?

    Just wanna see if anyone has some advice!

    I have a couple TSC120 Packaged cooling RTU's giving me similar issues.

    Heres whats going on with one unit...

    OA Temp 90 Degrees
    Entering Coil Temp 75 degrees
    Leaving Temp 59 Degrees
    Circuit 1 270/75 14 SH
    Circuit 2 320/80 30 SH

    Now the only reson my pressures on circuit 2 are so high, was because i wanted to add some gas and see if i could get any reaction out of my superheat. obviously not much success dont seem to have any significant drop across the drier..
    According to the Service Facts with the outdoor temp and entering air temp i should def be running a lower superheat...
    i mean i find circuit 1 acceptable but circuit 2 is just way out there...this didnt create a call, just came across this on an inspection

  2. #2
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,702
    What is the pre added charge pressures?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  3. #3
    Join Date
    May 2007
    Posts
    41
    i believe around 280/62 35+ superheat

    really wish someone at trane would spend the extra few cents to put in a liquid port!!! ahhhh

  4. #4
    Join Date
    Jan 2003
    Location
    Kansas City
    Posts
    1,482
    If it is a fixed restrictor, I would say both suction pressures and both superheat readings are high. Is the mixed air temp higher than the return temp you recorded due to outside air? Is the humidity high? What is the entering air temp wet bulb? If the orifices were restricted, I would be looking for a much lower suction pressure. Kinda sounds like a high load-----Assuming this is an R-22 system.

  5. #5
    Join Date
    May 2007
    Posts
    13
    I have seen this condition before also. I'm assuming that you haver a short orifice manifold. I have seen where some of the orifices become restricted and cause your symptoms to occur. Usually you can see which ones are restricted if you pull the filter access panel off quickly while the circuit is running and look for frost build up next the crimps where the orifices are located. If that is the case, you have to replace the entire manifold. Be sure to blow out the liquid line from the filter drier and install install a drier rated for the tonnage of the unit.

  6. #6
    Join Date
    May 2007
    Posts
    732
    Check for temperature drop across the filter drier, I have seen a few restricted on Voyager units. Trane put very small driers on the units where I found this problem, one or two sizes smaller than the size suggested by selection charts.

  7. #7
    Join Date
    Dec 2005
    Posts
    1,908
    I recommend to cut those orifice out (POS) and order a txv kit. You'll see the difference. Or if you want, you can build a TXV kit yourself.

    Done them too many times - trane, carrier.

    TXV is much better. Cost customer one time but better in long run.

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