Page 1 of 2 12 LastLast
Results 1 to 13 of 17
  1. #1
    Join Date
    Aug 2006
    Location
    Vancouver , Canada
    Posts
    310

    Liebert Start up question(s)

    Greetings:

    Just a brain picking exercise - ( I have been working on Lieberts for nearly 30 years - iCOM trained , couple of AM/AG training sessions etc. )

    Just comissioning a VS053WUA000266A ( Large screen iCOM, water cooled, 15 tons, 4 step Carlyle, upflow, 407c, rear return, blah , blah, blah )

    1) System # 1 is defintiely overcharged - high subcooling, good superheat but running OK till I get to trim the charge.
    2) System # 2 DOA - no refrigerant - snapped off cap tube in the spring at the base of the bellows - likely shipping vibration. Will get parts and fix later - - - -
    3) This is where I am stumped, and I got on too late for Tech Support - When the unit has been running for 20+ minutes, ( 205 head, 84 psi suction @ 82*F R/A ) loaded 100% , I shut the unit off on the iCOM and the fan and compressor shut off in unison - LLsolenoid drops and that is it. If I re-start and let the unit run for another 20 minutes, pull the wire on the LLSV ( no hot gas either on this one ) the suction goes down to about 3 '' vacuum and shuts off.
    Page 20 of the iCOM book states that the unit has a pump down ( like they have for years ) but I am not getting it in this case. It also states that this is set from the factory.

    Anyone else run into this ??? Thanks for looking - - - -

    Freonguy CM
    Superheat and subcooling tell it all !

  2. #2
    Join Date
    Jul 2012
    Location
    Southwest
    Posts
    114
    Has someone bypassed the low pressure cutout to remove the pumpdown? Or is the LP switch bad? Wait, where is it reading LP from? is it on a port someone back seated so its not reading? Those are the two routes I would be chasing.

  3. #3
    Join Date
    Jan 2007
    Location
    Charm City--the city that bleeds
    Posts
    2,790
    Just commissioning a DS077 recently had lift me with the same question, as the compressors stop cold(scrolls). The LP port is (brazed) inside the service valve, and cannot be backseated out of the equation. IDK guess they don't pumpdown the scrolls??
    Can you believe the specs for control wire? 18 is not even on the chart, up to 10AWG for runs over 126 ft.
    It's great to be alive and pumping oxygen!

  4. #4
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    EVERY Large upflow down flow has a cold start delay set for 3 minutes at start up.

    It will, on its own ignore the lp switch for 3 minutes on start up.

  5. #5
    Join Date
    Aug 2012
    Location
    Silver Creek, Ny
    Posts
    94

    Confused control wire...what??

    [QUOTE=The Doctor;14047631]Just commissioning a DS077 recently had lift me with the same question, as the compressors stop cold(scrolls). The LP port is (brazed) inside the service valve, and cannot be backseated out of the equation. IDK guess they don't pumpdown the scrolls??
    Can you believe the specs for control wire? 18 is not even on the chart, up to 10AWG for runs over 126 ft.

    Are we talking normal 24v control or some cost saving 120v control (cost saving because there is no 24v control system, just all line voltage)

  6. #6
    Join Date
    Aug 2006
    Location
    Vancouver , Canada
    Posts
    310
    Quote Originally Posted by Six View Post
    EVERY Large upflow down flow has a cold start delay set for 3 minutes at start up.

    It will, on its own ignore the lp switch for 3 minutes on start up.
    Six:
    As noted, AFTER 20 minutes of running, it still dumps the compressor immediately on shutting off the control OFF / ON @ the iCOM touch pad.
    I have worked on / commissioned well over 200 different Lieberts in my time - this one is brand new and I am the commissioning dude - doesn't make sense to me right now.

    B1978 says:
    Has someone bypassed the low pressure cutout to remove the pumpdown? Or is the LP switch bad? Wait, where is it reading LP from? is it on a port someone back seated so its not reading? Those are the two routes I would be chasing

    B1978:
    As noted, I am the commissioner, AND, the compressor does shut off @ 3'' vacuum when you pull the LLSV wire. Nothing has been dicked with, and it does not even try to pump down. Compressor and fan shut off at the same time.

    Like I said, I have a call in to Liebert Tech Support - I didn't work for the next three days, so there may be a reply when I get back to my office. Will let you all know what gives.

    Thanks so far!

    Freonguy CM
    Superheat and subcooling tell it all !

  7. #7
    Join Date
    Jul 2012
    Location
    Southwest
    Posts
    114
    Maybe its the wrong LP switch for the refrigerant? 407c?

  8. #8
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    maybe it is a pumpout system
    not a pump down system?
    like copeland recommends for scrolls??????
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  9. #9
    Join Date
    Jan 2007
    Location
    Charm City--the city that bleeds
    Posts
    2,790
    [QUOTE=J-thetechwizard;14050921]
    Quote Originally Posted by The Doctor View Post
    Just commissioning a DS077 recently had lift me with the same question, as the compressors stop cold(scrolls). The LP port is (brazed) inside the service valve, and cannot be backseated out of the equation. IDK guess they don't pumpdown the scrolls??
    Can you believe the specs for control wire? 18 is not even on the chart, up to 10AWG for runs over 126 ft.

    Are we talking normal 24v control or some cost saving 120v control (cost saving because there is no 24v control system, just all line voltage)
    we're talkin' 24 volts. Our installers re-used the existing 18 stranded for the interlock. The transformer was tapped alright for the line voltage, and yielded 26.7 volts on the new system's interlock--but on startup it still blew the low voltage CB and never brought on the fans or the pump.
    I had already bypassed the fire panel due to a pinched wire in that menagerie, so I went right to the book. Table 10 in the drycooler manual, page 28 or so. The valves inside are all three-way valves, which gave the electricians time to get it together.

    And I'm hearing that it's official--no pumpdown on the scrolls.
    It's great to be alive and pumping oxygen!

  10. #10
    Join Date
    Aug 2006
    Location
    Vancouver , Canada
    Posts
    310
    Gentle(persons):

    Just got off the phone with Liebert - Tech Support.

    Seems as though the ' pump down ' mode has been disabled for about a year or so, scrolls or Carlyle - I suppose they should make that change in the iCOM book - I will be sure to add that to my comments on the Startup Sheet.

    I wish they would have returned my call from last Thursday though!! Oh well - - - - -

    Freonguy CM
    Superheat and subcooling tell it all !

  11. #11
    Join Date
    Aug 2011
    Location
    Salem Oregon
    Posts
    26
    Weird. Did they add a crank case heater?

  12. #12
    Join Date
    Jan 2007
    Location
    Charm City--the city that bleeds
    Posts
    2,790
    Quote Originally Posted by Eric S View Post
    Weird. Did they add a crank case heater?
    Yes, and "crankcase heater" has its own line in the startup sheet now too.
    It's great to be alive and pumping oxygen!

  13. #13
    Join Date
    Jul 2008
    Location
    Metro Atlanta
    Posts
    70
    I believe it is ok to pump down scrolls, just not into a vacuum. When scrolls pump down below 0 PSIG the windings are prone to deterioration, but i thought pumping them down to, say 20 PSIG, would still be beneficial upon start up. I didn't know Liebert made this change either.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event