oil carryover carrier 5H 2

[pelu]

Hi,

I have a problem with a Carrier 5H compressor that carryover alot of oil to the liquid side. I can't find any obvious reasons. Lp 62psi, Hp 220psi (condensor dirty), Oilp 120psi.

Anyone with experience of such problems and I would be very thankful for your input.

Regards

 

[imok2]

Losing oil could be caused by the following :
·A flooded compressor is circulating oil.
·Too much oil is in the system.
·The system is not piped correctly (there are no oil traps or the piping is too large).
·There is liquid migration during the off cycle.
·TXV is out of adjustment (too little superheat-flooding).
·There aren’t enough defrosts if it's a low-temperature machine, (coil ices up)if a dry expansion coil
·The wrong type or viscosity of oil was used.

Oil logged in the evaporator will coat the inner wall of the coil and reduce heat transfer through the walls. This will cause a loss of capacity and poor performance. Then the compressor will be robbed of some of its crankcase oil and will run with a lower-than-normal oil level. This may score or ruin mechanical parts in the compressor.
Some symptoms of an oil-logged evaporator include:
·Noisy compressor;
·Low oil level in the sight glass on the compressor’s crankcase;
·TXV has a hard time controlling superheat (hunting);
·Low evaporator and compressor superheat; and
·Warmer-than-normal temperatures with loss of capacity.

Here is a more-detailed look at those symptoms.
Many times, a compressor that is flooding with refrigerant will turn into an oil pumper. The crankcase will foam from the liquid refrigerant flashing in it. Small oil droplets entrained in the oil will be pumped through the compressor. This will oil log many components in the system. The velocity of the refrigerant traveling through the lines and P-traps will try to return the oil from the system to the crankcase. Even an oil separator in the compressor’s discharge line may have a hard time keeping up with excess oil in circulation. Oil will continue to get into the system if the flooding is not remedied.

If the TXV has a hard time controlling superheat it will also see too much oil passing through it. The evaporator’s tailpipe will be oil logged and the inside of the tubes will be coated with oil. The remote bulb of the TXV at the evaporator outlet will have a hard time sensing a true evaporator outlet temperature because of the reduced heat transfer through the line.
The TXV will hunt. As a result, constant superheat will not be maintained. The TXV remote bulb may sense a warmer-than-normal temperature from the oil insulating the inside of the line. This could make the TXV run a low superheat and flood or slug the compressor with refrigerant. Often the sight glass in the liquid line will be discolored with a yellow or brown tint from refrigerant and oil flowing through it. Also: If the TXV is running low superheat, this will cause the compressor superheat to run lower. It would help to know if this is a low, medium or hi temp system

 

[pelu]

imok2,

Thank you for your reply, I really appreciate it!