York chiller stumper

[davo]

York Millenium Model# YSBBBSO-CFC
R-22

135 ton (or so I am told)

Compressor # 163S
Rotary Screw Compressor
Problem: high oil filter pressure differential.


I had just replaced both oil filters 3 months ago. (this has the twin oil filter system that runs only one filter at a time. You can move the lever to switch between the oil filters). And we also had the oil tested at the same time by Trane Labs. All okay.

This chiller went off on "clogged oil filter". I noticed oil was pumped out of oil separator, into the evap, and also locked out on low oil level.
I pumped some oil in to the separator for start up (1 gallon York C type oil).

I started the chiller and it went off after about 30 second on "clogged oil filter. Filter differential was 28 psi.

I tried the other filter, and it did the same thing.

I replaced both the oil filters, and the filter differential started at 9 psi, and rose to 17.5 after 10 min. run time. I noticed a "excessive refrigerant charge" warning. Maint told me they added 100 lbs r-22 last month to get TD up.

I removed 100 lbs r-22 and let run over night with a 50 degree discharge superheat.

I returned in the AM and all oil had returned, but noticed the filter differential pressure rose to 20.5 overnight, and a "dirty oil filter" warning was present.
I balanced discharge superheat to 45 degrees at full load with 55 degree CW IN tempand 55degree CW OUT. Refrigerant Pressures are 209 discharge and 72 suction.

Oil Temp is 119 leaving the oil cooler (verified with a thermanometer), oil solenoid is energized.

Oil Pressure is 228.
There is one oil transducer located at the bottom of the oil separator and one in a metal block located in the outlet of the oil cooler eat exchanger. This metal also has the oil temp sensor in it.
It seems to have a restriction some where in the oil filter/cooling circuit.

Oil pressure transducers zero out when system is shut down.

Is there a strainer in this circuit?

Could the oil cooler be restricted?

Is there anything else I should look for?

Any help would be very helpful.

I have verified the filters are correct, and the exact same chiller next to is runs a 9.5 oil filter differential and has the same filters.

Thanks in advance.

[davo]

UPDATE:

Maintenance man called me and said chiller was off on remote stop.

The filter differential was 6 psi. while off. Could the pressure tansducers be going bad intermittently?

[Dallas Duster]

Pressure transducers are usually within 5 psi of gauge . Might be worth rechecking with a gauge to verify.

[servicetrane]

davo:
I had a similar problem and what I did was this, recover the refrigerant and lower the oil cooler and wash-house, and put it back, I try to keep the temperature of water entering the condenser at 88 ° F with a DT 10 ° f and keeping the oil temperature to 135 ° F, adjustable by the flow of refrigerant into the oil heat exchanger
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[klove]

209 discharge, 72 suction, and 228 oil?

[davo]

209 discharge, 72 suction, and 228 oil?


Yea, I see that now too. I will review the readings Sunday morning.

I will also raise the oil temp to 135 degrees.

[9675]

bet you a dollar balance piston is bad, causing excess use of oil, filter cant keep up with flow and shows clogged,trying to charge to approach is not a good idea with an oil logged chiller.

[davo]

bet you a dollar balance piston is bad, causing excess use of oil, filter cant keep up with flow and shows clogged,trying to charge to approach is not a good idea with an oil logged chiller.


The oil washed out due to excessive refrigerant charge, and out weather temps falling down here. I have allowed the oil to return to the oil separator, which seems to be maintaining proper oil level now (50 degrees discharge supereat).

When you say "Balance Piston", what do you mean?
If such balance piston were bad, would the over all oil pressure (measured after the filter and oil cooler) show lower then the properly operating chiller next to this one?
(they are hooked in parallel)


I have to admit, I am no Chiller Guru, and this is the only two Yorks we work on (out of 3 total I have ever even seen, including these two).
The company who owns them, likes our prompt service.
I have diagnosed & repaired several problems on these chillers the local chiller companies have never identified mis-diagnosed for 15 years. I have been straigt forward with the owner, and told him upfront of my inexperience with these, but they insist my inexperience has proven better then the local companies around here (mostly due to the manuals and advice provided from members here).
Every call on these is a learning experience for me, and I appreciate the help from you all, which has proven priceless in the past.

[klove]

Does this compressor have an oil injection valve on it? If it does, it will be in the center of the rotor housing on the side (3 o'clock position if you're looking down the driveline from the motor). If it has oil injection, shut it off. It creates high oil flow conditions and increases filter DP - especially on those screwed up duplex filters. Being a C style I doubt the oil injection is there, but it's best to be sure.

Also make sure the condenser transducer is reading correctly by testing against an accurate gauge. Don't ask why, I just know that I've had high filter DP on two YS's that was straightened out by replacing the condenser transducer. Has to be something in the logic of the micro misinterpreting the signal, even though those signals aren't supposed to cross.

You're on the right track with getting the oil back (refgt should be clear as water with no foaming) before going further. There are things inside the compressor that can cause high oil flow with resulting hi filter DP as 9675 said. Has this compressor ever been rebuilt? How many operating hours are on it since start-up/rebuild? Are it's running conditions normal, or does it have to run a good bit under some pretty abnormal conditions?

[supertek65]

please let me know what the hell was happening with this thing??????????????

frank

[davo]

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.

[Phisher]

I had the same problem with high pressure drop on a McQuay screw. A large piece of the discharge check valve seat broke off and ended up in the oil separator return line restricting oil flow. I would check for pressure drop between the compressor discharge and entering side of the oil filter.

[servicetrane]

that oil level has separador.si oil level is high, drain oil to keep 1 / 2 sight glass
Excessive refrigerant charge alarm is caused by oil in the evaporator water temperatures keep the tower in 88 ° f not add more oil to the separator

[cperk]

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?

[supertek65]

are you sure?????????????

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

oil pressure - crankcase pressure???



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?

[davo]

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.

[servicetrane]

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

[jfridge]

Does this chiller ever run unloaded

[klove]

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?

[cperk]

are you sure?????????????

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

oil pressure - crankcase pressure???

I thought he said screw not recip.

[Entropie]

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.

[davo]

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!

[jfridge]

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