Carrier Screw Chiller oil loss problem

[pbcd]

I have a R-22 Carrier Screw Frame 4 chiller. Model number 23XL4343ED40 (300 tons). The unit runs 24/7 and is at approximately 50% FLA during the day. About two weeks ago I changed the oil and filter. I added oil until the level (non operating) was at the center of the lower sight glass (approx. 10 gals.) as prescribed in the Carrier procedures. The other night the unit shut down on "Oil Level Sensor". Someone else responded to the call and restarted the unit. The next day I checked the chiller and found the "operating" oil level to be in the center of the upper sight glass and the differential oil pressure at 75 psi. Today the operating oil level in at the center of the lower sight glass.

Does anyone have any thoughts as why I lost my oil level (assuming the oil level sensor is not faulty)?

[mdp]

Good question, I did a little refresher reading and it sounds like you changed the oil properly. One thing you might want to lok at is the water side. High evaporator water temperature or low condennser water temperatures can give you nuisance trips.

[pbcd]

mdp


My CW temp. runs a steady 45 degrees. and my cond. temp. runs at approx. 78 - 82 degrees. I live in Hawaii so my night ambient temp. does not drop very much.


In reference to pg. 8 and 11 of the publication under "Oil Loss Prevention", it mentions about the PIC controls detecting hot oil draining down the suction pipe (via the rotor inlet temp. sensor) and responds by moving the slide valve to increase suction velocity. I'll check out the rotor sensor and slide valve operation next week.

[chiller joe]

I just rebuilt 2 of those 1st make sure your cond water is not to cold then check approach on cooler also on the 23xl I have had to remove alot of the r-22 from some of these best way to charge is add a sight glass on the oil skim line (learned @ fact school)and charge till you see oil not refrigernt coming back if the machine has to much of a charge skim line will only pull back most refrigerantand not the cooler so make sure your cooler is not oil logged

good luck

[pbcd]

chiller joe

Thanks for your reply. I live in Hawaii so my condenser water remains pretty much about 80 degrees. My cooler approach is 1 degree. The skim line that you mentioned is on the Frame 1 and 2 models. The Frame 4 that I have does not have it.

[chiller-killer]

YOU NEED TO START ADDING SOME REFRIGERANT TO THE MACHINE TRY 30LBS AT FIRST. KEEP AN EYE ON YOUR SIGHT GLASS. DISCHARGE SUPERHEAT IS ALSO IMPORTANT.

[pbcd]

Chiller-killer
My frame 4 machine does not have a sightglass. The manual states to charge the unit by utilizing the cooler approach. My approach is 3 degrees at 50% load (will try to let CW warm up and get an approach reading at 100% load). Do you know what's the design cooler approach?

[twcpipes]

You never had this problem until you changed the oil? And the water temps are also the same they always have been?

[techtalker]

The design approach can vary for any particular machine. If you want the design approach, talk to Carrier's Replacement Component Division and tell them the machine's serial number. They can send you the design condition for the unit.

3 degrees at only 50% load sounds high. Mod of these units are 1-2 degrees evaporator approach at full load (ealier on you said it was 1 degree).

Since you first posted, how has the machine been running?

[pbcd]

I stand corrected ........ my condenser approach is 1 degree and my cooler approach is 3 degree (at part load). I recently shut down the chiller and let the CW warm up. At 100% load, my cooler approach was 4 degrees. Recently my oil level has been maintaining. The oil problem appears to have started after the oil change. I was recently told that someone else repaired a large oil leak just prior to me changing oil. The unit might have lost enough refrigerant charge to possibly be causing my problem. Water temp. remain constant.