View Full Version : Oily YT
08-19-2009, 09:48 PM
Got an oil logged YT. Had a panel problem and the oil pump ran continuously for umpteen days, among other goofy stuff.
Good hot gas flow through the eductor, checked the eductor for debris,
changed out the oil return drier. Anybody know of any other ideas to get the oil coming back, other than distilling?
08-20-2009, 05:57 AM
Does the machine have enough load to keep it running at close to full load % if so I would attemp to see if I could remove oil from machine first watch your oil level in oil sump normal level 3/4 upper glass in purge cycle upper glass empty. If you can remove oil this way you may not need to remove the charge to clean if not then it back to square one.
08-20-2009, 08:26 AM
Is the inlet valve from the oil return system to the compressor rotor support (gear housing) cold or warm/lukewarm/hot during operation, and what is the loading on the chiller? Under "normal" conditions, it shouldn't take more than about 4 to 6 hours to get 75% of the oil back unless there's a problem in the machine or the oil return. Also, what is the compressor model #? Charge being low can affect the evap level, which in turn affects pickup, also.
08-20-2009, 08:32 AM
It's a YDTJ 95. R-11.
One tech told me that when the oil logging reaches a certain level, that it gets too heavy for the eductor to lift it up to the compressor.
We've got some load the last couple days, so hopefully a little more gas flow through the eductor will help.
08-20-2009, 08:49 AM
Sounds like someone repeating something they don't know to be a fact. Mix 20 gal of oil with 1000# of refgt, and it gets pretty thin. I've pulled as much as 200% too much out of some machines, and never had the eductor not lift it. With everything correct and a clean chiller, the refgt should be clear as water within 48-72 hours, maybe less.
08-20-2009, 02:43 PM
What kind of head pressure are you running? And are you loaded up to 80% or so? Any carryover? Try running the tower water temps up along w/ running as much loaded as possible. Charge issues, eductor systems, or internal problems are about your only options.
I agree w/ Klove on the eductor, refrigerant will thin the oil pretty good & the eductor is pulling back oil & refrigerant mix, the refrigerant is then vented off after it boils off in the sump.
08-20-2009, 09:44 PM
Went there today, and the oil is coming back with a good load on the machine. Took about a gallon and a half out. I'm still not happy with the line temp going back to the gearcase, but the oil is coming back. Still had over three degrees approach in the evap, but it is getting smaller as it goes. Maybe I'll drop a See All in the line at least temporarily so I can see what's happening.
The person with the oil weight theory is an OEM friend from way back.
08-20-2009, 10:35 PM
There's several things you can look at to determine issues with the "oil scavenging/skimming system" on the Yorks. Charge level, vent line solenoid operation, rotor support vs evap pressure (to determine balance piston seal integrity and/or vent valve operation), loading levels (unlike what many are led to believe, low loads or high water temps running manually unloaded with vanes closing off will give better oil return as a general rule, as long as lift is anywhere near reasonable), and obviously the eductor system from a restriction standpoint. There have even been a few that the eductor would pass enough hot gas that it would raise the sump pressure up during high loading conditions and kill the return. Had to throttle the hot gas line back to get them to operate. During anywhere near "normal" operating conditions, the service valve at the rotor support return should be cold, area surrounding threads shouldn't be more than warm. No hard numbers to put on the temps at any given point on the lines, but the warmer that valve, the less refgt/oil mix is coming back. Sight glass on the return line is an excellent idea (done it numerous times), but temp really tells the story. If you have doubts about the integerity of the oil return system and everything seems ok mechanically, try manually loading/unloading for 15 minute periods and see what effect it has on the inut line temp.
08-22-2009, 10:00 AM
The statement about throttling the gas line seems to coincide with what I've observed.
The line is cooler at low loads than at higher loads.
I'll give it a try when I get back there.
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