Trane Chiller Oil flow

[AC_ABI]

Hi All,

This is my first post and i apologise in advance if i am duplicating, but i have searched various terms for at least an hour and cannot find an answer to my query!

I am receiving this information second hand from one of my engineers so forgive me if my knowledge of the situation is a bit vague!

I have a Trane ERTAA213 Chiller and it is having a problem with tripping on low oil flow, however it only seems to be tripping on "pump down" upon achieving setpoint. The oil diff switch has been replaced already and it seemed to run ok for a few days but then the fault reared its ugly head again!

The oil solenoid valve and coil have been checked and appear to be working ok, and the next step appears to be to replace the oil + filter (which in good practice should have been done when the diff switch was replaced).

The problem being that i have also heard that there are certain oil ports / sliders in the compressor itself that could require replacement which cause the same fault!
I have also been told that this can be a complicated change and only has approx 70% success rate, if done wrong its bye bye compressor!

Does anyone know a lot about these chillers and if so could you point me in the right direction, as i dont want to keep going back to the same fault.

Any help would be greatly appreciated!

Regards

[Grizzly]

Change the filter!

Grizzly

[AlexG]

Does this fault appear during operation or just after compressor being stopped by setpoint reached?

[goshen]

Hi
you got good advice change the filter !!

Low Oil Flow - Cprsr A CMR The differential oil pressure switch remained opened for more
than 20 contiguous seconds on Cprsr A.
Note: Although GP cmprs do not have pressure switch or Oil
Line solenoid, this diagnostic is still active. The input must be
jumpered for normal operation on GP cmprs.

good luck

[CV_Geardrive]

Hi ABI,
RTAA with CHHB compressors have two types of oil alarm.
When running LOW OIL FLOW and when stopping OIL FLOW CONTROL.
The setting of diff pressure switch should be 50PSIG.
When the compressor stopping, the control initiate a continuous unload signal for 24 seconds and then close the oil solenoid valve.
Then wait for 6 seconds to check if the diff pressure switch will open.
If open then shut down normally.
If not shut down on OIL FLOW CONTROL alarm.
In case of low ambient temperature discharge pressure in not high enough to initiate an open condition of switch in 6 seconds while the suction pressure is high due to unload condition. (Small differential refrigerant pressure)
Set the differential pressure switch to 40PSIG and don’t forget to reset it to 50PSIG or 60PSIG during summer.
If your alarm is LOW OIL FLOW please let us know running conditions of circuit at the time of alarm.
All these in respect that oil solenoid valve is operating well
Regards,
CV

[AC_ABI]

Does this fault appear during operation or just after compressor being stopped by setpoint reached?

AlexG, the fault shows only when the unit is stopping / pumping down upon reaching setpoint. The unit will run fine for hours without any alarms or latched faults.

The trane manual suggests that the oil filter is oversized for its application and therefore does not require replacement, the only time it requires replacement is if the oil is contaminated or the compressor fails!

[AlexG]

AC_ABI, my explaination is similar to Geardrive's one. One second before compressor stops, oil solenoid valve deenergizes to check oil safety system. It means oil dif switch must be opend in this 1 second. If it stays closed it means safety sistem doesnt work. So u have alarm message. Disassemble oil switch and check "paper" inside can block contact movement.