Liebert Start up question(s)

[freonguy]

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

[B1978]

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.

[The Doctor]

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.

[J-thetechwizard]

[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)

[The Doctor]

[QUOTE=J-thetechwizard;14050921]

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.

[freonguy]

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

[Push It]

Gentle(persons):

- 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.



Freonguy CM

Only 25K more units to sell till they can use up all the old books.
Sure would be nice if they put a bulletin about this in that start up literature.

[Eric S]

Weird. Did they add a crank case heater?

[The Doctor]

Weird. Did they add a crank case heater?

Yes, and "crankcase heater" has its own line in the startup sheet now too.

[Six]

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.

[freonguy]

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

[B1978]

Maybe its the wrong LP switch for the refrigerant? 407c?

[supertek65]

maybe it is a pumpout system
not a pump down system?
like copeland recommends for scrolls??????