Hello everybody,

There is heating/air conditioning system with two heat pump. Those two heat pumps have seperate refrigerant cycles with two evaporators for each - one air source and one water source. System's principle scheme is shown below:

scheme.png

There are two seasonal modes in this system. In the summer mode solenoid valve installed in the refrigerant cycle close the cycle to the air source evaporator and the heat pump works like a water to water heat pump and the refrigerant cycle goes through the water source evaporator. In that mode warm water coming from fancoils installed in the office facilities are cooled and than it is supplying back to the fancoils. The energy taken from the offices are used to heat DHW and when the water temperature reaches setpoint it is directed to the technology line. That's how the summer mode works.

In the winter mode second solenoid are closed and refrigerant cycle is directed to the air source evaporator which takes the heat from exhausted air from technology and bring it to the DHW and heating system. in this mode heat pump works like an air to water heat pump.

After a half of the year one the heat pump's compressor broke up. Malfunction symptoms:
1) Metallic sound inside compressor;
2) Higher working current than usual;

Guys, what do you think is the main reason for this malfunction? Could it be due to oil returning issue? Oil seperator isn't installed. (Forgot to mention compressor type - it is Copeland SCROLL compressors)
Maybe oil is trapped somewhere in one of the evaporators and cannot return?
I will be very thankful for your help.