Trane Heat Pump Bad Compressor

[cfcitywide]

This is a water cooled heat pump mdl GETA018 with a Techemseh RKA5518EXD. Unit compressor tripping on OL due to locked rotor. I replaced the compressor with the same and will not return until tomorrow to reinstall into sleeve which contains the blower assembly. This looks like it has been changed before and I was told that many others are experiencing compressor failures in the building. I am not sure what the building is using as Heat exchanger and will get deltas/voltage/amp draws etc... I retrieved only 2 oz of oil from the failed compressor and it was very clean. My question is what might cause poor oil return on this unit? It is all OEM including suction acumulator. I did notice the TXV was tight at 2 o'clock but NOT insulated. Perhaps it was hunting and washed the oil out? but why are so many others losing compressors in the building. The unit is only 4 years old. I have attached some pics of the sleeve unit

[beenthere]

How much oil did you get out of the coaxial.

Start checking the water flow, and the heat source.
Water flow could be too low, or too cool.

[cfcitywide]

I'll check the flow rates and deltas today. I didn't drain the coaxlial. Thats probablly where it's at. Too cold or low flow will cause low velocity? Spec sheets give ratings for 45* water so it seems that this would be acceptable. What would be considered too low of a temp? and how does this cause oil migration? The specs say it has 508 cc's which converts to 17.17752355068753 ounces. That's alot of oil! What types of cooling towers do they run in these buidings in the winter? Some type of open bin inside?

[beenthere]

If 45° is ok, 40° isn't.
Check the specs on the unit for the GPM of flow it needs.

1.5 GPM per ton at 45° may be acceptable, but, 1 GPM per ton at 45° may be too low.

Most likely, there is a boiler some where in the building.
You'll want to find it, and see how its controls are set up. What temp it is suppose to maintain.

Low flow, or low water temp makes the coaxial too cold.
The coaxial becomes flooded with both liquid refrigerant and oil.
The velocity of the refrigerant slows, and the oil being heavier, doesn't stay moving with the refrigerant.

[cfcitywide]

The low water temp makes sense but wouldn't low flow increase the head thus the back press? What would cool the water? A chiller? I only seen 1 supply and 1 return line for the heat pump so I'm not sure if there is even a boiler in the building. I thouhgt the living units were heating by the heat pumps only with no auxillary. I'll have to get the building engineer to increase water temp if this is the case. I'm heading over in about an hour and I'll post my findings.

[beenthere]

In cooling mode, they would run high head.
But, in cooling mode, they will have a low suction and head pressure, because the coaxial is the evap.

Has to be a heat source somewhere, to heat the water.