Hey guys
Got a heat-recovery chiller that does 180F hot water on the condenser and 85F water on the evap, refrigerant r-134a and poe oil with brazed plate heat exchangers and 2 circuits.Each circuit has a set of identical tandem copeland scroll compressors ( all 4 compressors are the same tonnage)with an oil equalizer line between them and they sit on top of the heat exchangers.Both circuits share the same heat exchangers but like i mentioned above they are independent circuits..This is a fairly simple design electronic expansion valves ,cranck-case heaters ,no oil separators and no pump down..Issue is we've been loosing compressors mechanically,usually they"ll last a couple of months sometimes even less before they die mechanically..Compressors don't seem to be slugging liquid refrigerant, am suspecting maybe an oil return issue ( to much restrictions through those heat plate exchangers) especially when one compressors is running alone ,oil degradation or the design itself high temperature/discharge pressures since its a heat recovery application ..Was thinking maybe adding liquid injection on the discharge line and even oil separators..I welcome any suggestions or information..thanks!
