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  1. #14
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
    Posts
    852
    Quote Originally Posted by davo View Post
    Okay, now I am pissed. I had all this typed and hit a wrong button and closed the site. I lost it all. Here it goes again.

    First a few things to be sure we are all on the same page:

    Diff Oil Press = (Oil Press - Evap Press) - Offset Pressure

    Where:

    Oil Press = Oil Pressure at Input to Compressor

    Evap Press = Evaporator Pressure

    Offset Press = Pressure differential betweene the oil pressure and evaporator pressure transducer output during the first 15 seconds of the Start Sequence. This is the transducer AUTO ZEROING.

    And:

    Filter Diff = (Filter Press - Oil Press) - Offset Pressure

    Where:

    Filter Press = Oil pressure at the input to Oil Filter

    Oil Press = Oil Pressure at Input to Compressor

    Offset Press = Pressure differential betweene the oil pressure and evaporator pressure transducer output during the first 15 seconds of the Start Sequence. This is the transducer AUTO ZEROING.

    Chiller #1 is the one with high oil pressure differential. I left it under slightly charged

    Upon Arrival:

    Diff Oil Press: #1 = 119.7 #2 = 130.2

    Diff Filter: #1 = 20.8 #2 = 9.6

    Oil: #1 = 193 #2 = 211

    Filter: #1 = 215 #2 = 221

    Evap Press: #1 = 77 #2 = 79

    Condenser Press: #1 = 208 #2 = 216

    Oil Temp: #1 = 117 degrees #2 = 115 degrees

    Discharge Superheat: #1 = 52 degrees #2 = 45 degrees

    Slide Valve Position: #1 = 100% #2 = 100%


    I found that the oil returned to chiller #1.
    I raised the oil temp on both chillers to 135 degrees. Chiller #1 DIFF FILTER PRESS dropped from 20.8 psig to 14.8 psig. Chiller #2 dropped from 9.6 psig to 8.7 psig. I can only assume this is due to the warmer oil thinning out.

    I brought the charge up to 45 degrees discharge superheat. The evap sight glass is a little under 1/2 full of liquid with the liquid clear like water., You can see the refrigerant boil off on top, but the boiling is clear too not "foamy".

    After adding charge, the refrigerant pressures, slide valve positions, amperage and water TD's are both the same. (58 CH water in, 46 out)
    Set for 42 LWT.

    Condenser water is 88 in and 96 out.

    I believe the compressor has never been rebuilt (15 years old)

    I know the main control board has been replaced (due to maintenance loggs). The unit (chiller #1) only shows 16,000 hours run time.

    The problem is, I was told the other one (#2) was left off for years and used only as backup due to it always loosing oil. It shows 68,000 hours.
    In fact, chiller 2 was shut down when I found it after the new owner bought the building.
    (I found some improper water in piping in the primary/secondary loop bypass and recommended how to re-pipe. It solved the problem and it has ran flawlessly for several years ago. That is how I got hooked up in this mess).

    These chillers run year round as this manufacturing facility runs 24/7.

    There is no boiler or even a tower bypass for cold weather operation.
    Last winter they had several shut downs due to too cold condenser water.
    You are figuring your diff. oil press wrong. It's discharge press. minus the oil press. past the filter which looks like 193 here. Remember screw, NO OIL PUMP. 215-193 what do you come up with on #1? 221-211 what do you come up with on #2?

  2. #15
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,832
    are you sure?????????????

    discharge pressure?? not crankcase pressure???/ suction pressure??

    oil pressure - crankcase pressure???


    Quote Originally Posted by cperk View Post
    You are figuring your diff. oil press wrong. It's discharge press. minus the oil press. past the filter which looks like 193 here. Remember screw, NO OIL PUMP. 215-193 what do you come up with on #1? 221-211 what do you come up with on #2?
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  3. #16
    Join Date
    Aug 2006
    Location
    Marco Island, Fl
    Posts
    729
    cperk,
    Those formulas are copied right out of the OM Manuals for this unit.
    What you essentilly described is "filter diff Press".
    The filter input transducer is located in the oil separator which is essentially the discharge pressure.

    servicetrane,
    Oil separator level glass furthest to the right is at 1/2 glass.

    I only added oil (1 gal) because it all washed out after maintenance added 125lbs r-22 to the system to try and raise the td. I removed the refrigerant and oil. (I actually measured it in a gallon container)

    I can not assure the water will stay at or above 88 degrees because they do not have a tower bypass or boiler. The tower is 600 tons (Marley SS tower) while I only have 270 tons of chillers because there is process equipment hooked to the tower as well.

    Klove,
    I did not see an oil injection on the compressor.

  4. #17
    Join Date
    Feb 2010
    Location
    MEXICO
    Posts
    472
    davo:

    as there is no assurance that the water temperature is 88 f, set it the flow of refrigerant into the oil cooler to maintain oil temperature between 135 f 145 f, with this you decrease dp

  5. #18
    Does this chiller ever run unloaded

  6. #19
    Join Date
    Dec 2008
    Location
    Dixiana, AL
    Posts
    2,609
    This machine has the duplex oil filter, which has a commuter valve that is famous for excess pressure drop. What is your filter DP when you swap filters? You may want to consider installing pressure taps at the service valves on the transducers to verify all readings. Are you positive that "auto-zero" is enabled?

  7. #20
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
    Posts
    852
    Quote Originally Posted by supertek65 View Post
    are you sure?????????????

    discharge pressure?? not crankcase pressure???/ suction pressure??

    oil pressure - crankcase pressure???
    I thought he said screw not recip.

  8. #21
    Join Date
    Feb 2009
    Location
    good old Europe
    Posts
    160
    The duplex oil filter housings are crap. Had one with an original pressure drop of 14 PSIG without filter cartridges installed! The duplex housings have phased out with the style D YS and the main oil line diameter has been increased, wonder why? High refrigerant content in the oil makes it even worse. I would replace the filterhousing with one of the style D. This should eliminate the problem. Auto zeroing is recommended.
    "Quality exists, when the price is long forgotten."

    Henry Royce

  9. #22
    Join Date
    Aug 2006
    Location
    Marco Island, Fl
    Posts
    729
    servicetrane: oil temp set to 135-140 degrees. will check this weekend. we will be in the low 60s at night.

    jfridge: yes it does run unloaded in cold weather and the small amount of time they are closed.

    cperk: this is a screw.

    Klove & enyrope: filter dp is the same on both filters. they are both new, installed the day I started this thread.

    I was wondering about the "Auto Zeroing" my self. Does anyone know how to check and see if it is turned on?

    Thanks again guys!

  10. #23
    remove checks from oil filters and lower head pressure before condemning balance piston,lower head =lower oil flow less oil flow = lower pressure drop
    close oil feed line into side of compressor to cut back on mass oil flow. That oil is used for noise attenuation only

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