Oil return issue on a commercial system!!

[bjkmiami]

Hi guys..
i have been working in industrial ref. industry however recently involved with some commercial projects(HFCs) which i am not so familiar with.Having an oil return issue on a system which has ZR copeland scrolls with R134 a refrigerant!!! any ideas about the root causes!!!

Appreciated in advance,,,

[NoNickName]

With so much information I wonder why no one hasn't got a clue.

[Magoo]

Hi Bjk.
the ZR range scrolls are a medium temperature -5.0'C > +5.0'C range compressor,(chillers ) possible problems could be extended high suction pressure conditions, oil separator would then be undersized may require a crankcase pressure regulator. Low suction super heat ( saturated liquid / flood back )