Hill Rack
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Thread: Hill Rack

  1. #1
    Join Date
    Aug 2009
    Posts
    85

    Hill Rack

    Hey Guys,
    I have a Hill rack Mod. AT4H4500RCM1, with some three comps, 4DK3R16METSK800,only two are working, i have to change the liquid line drier cores every 3 to 4 monts, they are totaly plugged.
    R409 refrigerant, Suction is 20psig, discharge is 193psig, drop leg temp. is 113*F, outside temp 83*F, all cond fans are working. Have to clean out TXV screens on a regular basis.

    Non condensibles in reciever ?

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,314
    Verify that all motors are rotating the correct direction.

    If that doesn't help, clean the condenser.

    I would also do an oil change and repeated drier changes to clean the system up.

    Have you looked into why one compressor isn't running?

  3. #3
    Join Date
    Aug 2009
    Posts
    85
    JP,

    Comp. has bin down for a while, blows fuses.

    Went on roof air coming out of fans is not warm.

    What affect would rotaion have on a three phase pump ?

    Is there a way to clean out reciever ?

  4. #4
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,314
    I meant rotation of the condenser fans, sorry if I was not clear.

    Reciprocating pumps don't care which direction they rotate.

    I'd check the wiring to that dead pump, verify that it is OK, then take action as needed.

    The air coming off the condenser..... Does it come straight up out of the fan or off at an angle?

    Short of recovering gas, removing any access plates and using tools to attempt to scru b it, I don't see a way to 'clean' the receiver.

    Why do you suspect non-condensibles? Your symptoms don't support that diagnosis.

  5. #5
    Join Date
    May 2008
    Location
    South Florida
    Posts
    58
    If your blowing fuses, you may have a burn out and if it is not valved off, including the oil return line, you moving crud into the system.

  6. #6
    Join Date
    Aug 2009
    Posts
    85
    Comp.is valved off.
    Suspect non condesibles beause of condition of cores.

    How can I have such a low discharge pressure and high drop leg temp ?

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,314
    Looking at PT chart, I don't think your head pressure or subcooling are out of line.

    193 head is about 118 degrees condensing and 113 degrees gives about 5 degrees SC. Fairly typical on a rack system.


    Non condensibles will cause high head pressure. You've got a dirty system. I'd change cores daily if it were one of mine.

  8. #8
    Join Date
    Jul 2005
    Location
    Southern California
    Posts
    580
    changing oil and changing suction filters might not hurt either...

  9. #9
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,064
    that sure is a high condensing pressure and drain leg temperature for a 83* ambient. your condenser most likely needs to be cleaned. any chance you took a discharge line temperature reading? willing to bet its scorching hot and burning your oil then plugging your driers.

  10. #10
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,064
    also non-condensable's are not your issue. 193# R-409a is 118*SCT and your drain leg is at 113*, that is only 5* off and most likely ambient subcooling.

  11. #11
    Join Date
    Aug 2009
    Posts
    85
    Thanks Guys,

    Doing oil, and oil filter change today, and will change drier cores accordingly.

  12. #12
    Join Date
    Dec 2011
    Location
    USA
    Posts
    66
    If you have felt suction cores they will hold a lot of dirt and as the oil passes through them it will pick some of it back up. So if the oil is discolored then change the suction cores also.

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