Mcquay Chiller oil carry over

[Aircon Kev]

Hi I have 3 Mcquay Energyplus B142.2 chillers on site. On 1 of the systems we were getting bubbles in the site glass and temperature reduction across filter drier, did all usual low gas, changed filter drier, even suspected valve before filter drier and changed that. All to no avail. When changing the valve we were surprised at just how much oil was in the condensor and the liquid line. The compressor has a built in oil separator and the heater is working ok. Can anyone shed any light on my problem I am getting no joy from the Mcquay rep.

[Brian_UK]

Has the unit been running at low load for extended periods?

Without full load operation at times the oil can 'stick' in the evaporator and on pipe walls which is why you may have found a lot in the various components.

[MQFS OZ]

Aircon Kev,

To much oil in the evaporator is usually associated with water cooled / flooded evaporator chillers that operate at low load for extended periods. Your Energyplus units are air cooled with DX evaporators. Oil logged DX evaporators are rare. The fact that you say there is excessive oil in the condenser tends to lead to maybe a faulty oil seperator or oil overcharge.
How long have you been servicing these chillers?
Its possible that previous service people overcharged the system with oil. Drain the excess oil and monitor the oil level over time checking to see if the level changes.
What's your operating discharge pressure?
With the compressor operating, listen to the oil separator, if its rattling inside you may have broken internal baffles causing oil to blow up the discharge line.

Good luck.

[Aircon Kev]

Brian thanks for that it does appear to have been running on low load and possibly overcharged with oil, we found also that the suction temperature sensor was defective. We have got it all up and running fine now. There is a pipe on the liquid line just before the expansion vv that goes back to the compressor via a solenoid vv any idea what it is for. Many thanks once again. Kev

[Aircon Kev]

Has the unit been running at low load for extended periods?

Without full load operation at times the oil can 'stick' in the evaporator and on pipe walls which is why you may have found a lot in the various components.

Brian thanks for that it does appear to have been running on low load and possibly overcharged with oil, we found also that the suction temperature sensor was defective. We have got it all up and running fine now. There is a pipe on the liquid line just before the expansion vv that goes back to the compressor via a solenoid vv any idea what it is for. Many thanks once again.

[Aircon Kev]

Aircon Kev,

To much oil in the evaporator is usually associated with water cooled / flooded evaporator chillers that operate at low load for extended periods. Your Energyplus units are air cooled with DX evaporators. Oil logged DX evaporators are rare. The fact that you say there is excessive oil in the condenser tends to lead to maybe a faulty oil seperator or oil overcharge.
How long have you been servicing these chillers?
Its possible that previous service people overcharged the system with oil. Drain the excess oil and monitor the oil level over time checking to see if the level changes.
What's your operating discharge pressure?
With the compressor operating, listen to the oil separator, if its rattling inside you may have broken internal baffles causing oil to blow up the discharge line.

Good luck.

oz, thanks for that it does appear to have been running on low load and possibly overcharged with oil, we found also that the suction temperature sensor was defective. We have got it all up and running fine now. There is a pipe on the liquid line just before the expansion vv that goes back to the compressor via a solenoid vv any idea what it is for. Many thanks once again.

[psycho]

Airconkev,
that pipe
mbe liquid injection feed via solenoid back to compressor, sometimes chillers have to run low load in low ambients , seems to make sense to me to check your head pressure controls to maintain a higher head , lower your stop evap water diff settings ,

never a dull moment

[MQFS OZ]

Kev, sorry for late reply, been away on leave.
The line you refer to with the solenoid is for compressor liquid injection to help lower discharge temp if it gets to high. Its default setting is 85c.
Regards MQFS OZ

[waseem]

i have a problem with chillers ( 2 units ) on high oil diffirential presuure on 4 compressors

[MQFS OZ]

Waseem,

What is the chillers model no?

If its a screw compressor chiller see below

High oil DP usually indicates a blocked oil filter.
Before you change the oil filters check and calibrate the Discharge and Oil Pressure Transducers.

Regards

[waseem]

how i can calibrate these oil & high pressure transducer ( it connect directly to controller with analoge input signal ) i donot if it able to calibrate and how ? please advice