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  1. #1
    Join Date
    Jun 2002
    Location
    Central Louisiana
    Posts
    460

    Hmm

    Hello Gents,

    I have a 500 ton York water cooled centrif that just won't bring back her oil to the sump when loaded at 60-70%.

    She has a proper oil charge. That was verified when we replaced the shaft seal last year and swapped in R-123 and new oil.

    I have replaced the eductor dryer cart and verified the eductor was not fouled.

    She runs at bottom of lower sight glass and oil pump chatters. If I lock her in at 90% for 24 hours, the oil will return, but as soon as she is placed back in auto and the load drops to 60-70%, the oil fades away again.

    My tower water is controlling well at 85-86 degrees. CWL is 43, CHR is 49 at 60% load.

    If we lose power and chiller shuts down, it's really hard to get her back up cause of low oil pressure shutdowns.

    Can you guys suggest anything that might help us prop her up thru the rest of the summer? We have no extra capacity. If I load her too high, the other chillers want to hunt and cycle.

    Thanks guys

    P.S. tower fan VFD is out, so fan runs max RPM's. Bypass valve works well in controlling basin temps, tho.

  2. #2
    What is the oil PRESSURE? Dont mean to sound rude, but has the problem just started, maybe with the VFD by-passed? What kind of evap approach do you have when low of oil? What is evap and cond pressure?

  3. #3
    Join Date
    Jun 2002
    Location
    Central Louisiana
    Posts
    460
    Thanks Ok, Ask anything you want,

    At 60% motor F.L.A. I have the following:

    Oil pressure varys from 22 to 25 PSI.

    Evap saturation temp is 42, chilled water leaving is 43.

    Condensor water leaving is 85, tower return is 81.

    Condensor saturation temp is 87.

    Compressor discharge temp is 115.

    Oil temp 145.

    Evap pressure is 6 PSIA, condensor is 16 PSIA.

    Pumps running with good pressures/flow.

    Problem has been around since we lost auto start capability on CW pump....Whenever chiller would lag off cycle, the pump would fail to restart, so we left it in hand 24/7. That's when we noticed oil migration.

    Then VFD failed first in inverter mode, so we ran it in hand where we at least had speed control. Now it's failed completely , so fan runs wide open.

    Today we lost auto control of tower bypass, so now we run it wide open. I can no longer control condensor water temps except by hand at bypass valve.

    The world is falling apart it seems....As it's now cooling season now, I ain't conserned about it lagging off and failing to restart, so CW pump auto start problem can be ignored.

    No one is gonna pay to get VFD fixed as long as the fan runs. They ain't going to pay to have Metasys fixed either as long as we can somehow keep chiller up.(You know how it goes)

    Anyway, I'm banging my head trying to keep this baby running right on the knife edge of low oil pressure. The oil is there, just hiding out.

  4. #4
    Join Date
    Dec 2002
    Posts
    603
    If you have other chillers on line, why don't you keep this one loaded and cycle some other machine?

  5. #5
    Join Date
    Jul 2004
    Location
    Visalia,CA
    Posts
    3
    If you swapped refrigerant to 123, have you checked your lift at partial load vs. full load? You may also have a lab seal (on the eye of the impeller) starting to fail.

  6. #6
    Join Date
    Jun 2002
    Location
    Central Louisiana
    Posts
    460
    Really can't lock her in at 90% like I would like. The 650 ton Carrier hermetic R-11 unit has a stuck control vane shaft, so it is already locked in at high load. The remaining 1000 Ton York would be cycling several times a night and she is already starting to exhibit starter problems.

    We expect to replace the 650 ton R-11 next year.

    As it stands now, if I lose the 500 ton 123 unit during the day the other 2 quickly go to current limit and chill water soars well above 55. To make matters worse, the plant isn't manned full time. So having units locked in is risky.

    Besides that, both low pressure units have bad flow switches that have been jumpered out several years.

    Hey, maybe when it all goes tits-up and we blow a charge due to high temps and bad flow switches and all the other stuff and they gotta rent some chillers...maybe then someone will want this stuff fixed, huh?

    How do I check lift?

  7. #7
    OMG,

    It sounds like you need to start fixing some of the small problems. Teardown the carrier to fix the vanes. ANd much more. I can see doing this kind of stuff for a night but not an extended amount of time.

    Just ones opinion

    Dave

  8. #8
    Join Date
    Mar 2001
    Location
    North Florida / South Georgia
    Posts
    100
    Check your oil filter. The oil pressure on your YT should be around 40psi. 22-25 is to low. Hopefully there wont be any sparklies in it. If after you change the filter and the pressure is still that low, then raise it at the regulater. Also fill the sump before you start it up to the top of the top glass. After three minites when the ventline solinoid opens up, the sump will foam somewhat for a few seconds, so if its low it will definitly trip on oil failure. Also see if you might be mixing chilled water. I would run the machine at full load and check your approach,s superheats and temperature drops across both barrel's. With only a 1 degree evaperator approach at 60% that seems a little low, same for the condensor. May be even slightly overcharged.

    Hope this helped...

    Bill

  9. #9
    I'm with Roadrunner on this one.....I have two YTC chillers, both run better than 40 psi oil pressure, except the #1 was at 18 psi before i changed the dreaded filter. It now runs at 44 psi with no problems. I worry though, that maybe your tower bypass is not as good as you might think. Maybe too cold in the evening? just a shot.

  10. #10
    Join Date
    Jun 2002
    Location
    Central Louisiana
    Posts
    460
    I'm thinking the oil pressure is so low cause she is low on oil level and that's why the pump is chattering....I agree it should be well above 30 PSI.

    I'll be here till midnight. I'll wait till it cools off and later tonight change the oil filter (not duplex, so I got to shut it down)

    2 months ago, she went down when the chilled water pump motor blew her peckerhead off, then The 1000 ton starter controller overheated and she crashed too. Then within minutes, The 650 R-11 motor windings over heated and she shut down. I got the R-11 up in minutes by changing the filter on the motor windings liquid line, and then discovered the 1000 ton had a cracked plastic coolant manifold. I got it back up once I fixed the leak and refilled it with coolant..........But the YT gave me fits all night due to low oil pressure and foaming.

    After we swapped pump motors, she wouldn't stay up due to low oil pressure. (just like you described, she would foam and then trip right after start-up) so I changed oil the filter while waiting for anti-recycle, but it made no diff, the pressure was still too low. I finally babied her up by getting her to run longer and longer tween trips.

    There is one thing that's got me suspicious, tho. When our tech showed up to replace the seal and swap to 123, he also performed some kinda mod on the oil system. I don't know what it is called, but he replaced piping from the oil cooler and to the purge unit with several blue flex hoses and added some type of manifold under the compressor and behind the purge unit.

    Maybe you guys have done this mod yourself and know what it's for.

    Thanks for all your suggestions, I'll do what I can with her tonight.

    I agree that the tower bypass is part of the problem. When I started this thread, I had auto control of it, but the next day, we lost that too. No one wants to pay JC to fix it. Half our Metasys stuff is in same condition.

  11. #11
    Yodaddy.....After your last post it's kinda obvious that your fighting a lot more than just oil problems. It sounds as though your involved in the "we dont have money for that" battle also. I think if i were you, i'd write down all the problems that you have on each of the respective units and present these facts to the powers that be, along with the possible cost senarios, and let them decide how best to proceed.

    I've found in the past, that if you let them decide, it's a lot better than the chiller going out and having a loss of service and the question being posed..."why didn't you tell us this stuff was in this bad of shape?" And suppose you do get the oil problem resolved, you still Have the other problems to deal with. Good luck buddy.

  12. #12
    Join Date
    Mar 2001
    Location
    North Florida / South Georgia
    Posts
    100
    Originally posted by Yodaddy
    I'm thinking the oil pressure is so low cause she is low on oil level and that's why the pump is chattering....I agree it should be well above 30 PSI.

    I'll be here till midnight. I'll wait till it cools off and later tonight change the oil filter (not duplex, so I got to shut it down)

    2 months ago, she went down when the chilled water pump motor blew her peckerhead off, then The 1000 ton starter controller overheated and she crashed too. Then within minutes, The 650 R-11 motor windings over heated and she shut down. I got the R-11 up in minutes by changing the filter on the motor windings liquid line, and then discovered the 1000 ton had a cracked plastic coolant manifold. I got it back up once I fixed the leak and refilled it with coolant..........But the YT gave me fits all night due to low oil pressure and foaming.

    After we swapped pump motors, she wouldn't stay up due to low oil pressure. (just like you described, she would foam and then trip right after start-up) so I changed oil the filter while waiting for anti-recycle, but it made no diff, the pressure was still too low. I finally babied her up by getting her to run longer and longer tween trips.

    There is one thing that's got me suspicious, tho. When our tech showed up to replace the seal and swap to 123, he also performed some kinda mod on the oil system. I don't know what it is called, but he replaced piping from the oil cooler and to the purge unit with several blue flex hoses and added some type of manifold under the compressor and behind the purge unit.

    Maybe you guys have done this mod yourself and know what it's for.

    Thanks for all your suggestions, I'll do what I can with her tonight.

    I agree that the tower bypass is part of the problem. When I started this thread, I had auto control of it, but the next day, we lost that too. No one wants to pay JC to fix it. Half our Metasys stuff is in same condition.
    Where is your machine (you) located? What is the night time...evening temperatures? If you have 75 to 80 degree entering condenser water at startup you shouldnt have any trouble with system depression. YT's likes them some cold condensor water, so I would keep the bypass off anyway and have all the condensor water go through the tower. Its more efficent. Unless this machine is a VSD (TM3) you should have no trouble with oil return, pressure or temperature running low condenser water temperatures. Even then, it would have to be very cold outside wherever you are. As far as the mods on the seal...if it was changed to the new John Crane cartridge style seal it has to be plumbed in by drilling a hole through the D Flange and piped in through a tee at the entering oil line top of the compressor. The manifold at the purge and the oil cooler with flex hoses...this is a new one on me. Let us know what you find.

    Bill


  13. #13
    Join Date
    Jun 2002
    Location
    Central Louisiana
    Posts
    460
    It's not like that here....all are aware and doing best they can. I really don't have any problem with management. We work together and communicate well.

    This is a Federal hospital facility, no money avail because of the war. Trying to keep the patients cool any way we can. Money must come from high above all here.

    Here is what I tried tonight:

    I discovered oil system mod is only to better control oil temps.

    I changed oil filter, pressure still same, 22-25.

    Valved off oil to purge unit to see if it was dumping oil. It wasn't.

    I'll keep digging.

    Thanks, Gents

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