York YCAS Chiller Problem

[pa2jonah]

:confused: Gentlemen,
I've got a customer with a YCAS0130EC46YFADBX that will lock out on a "Low Differential Oil Pressure" fault. Only in low ambient conditions (25 degrees and below) will this happen. The barrel on this unit burst and was replaced last year, by another contractor. From moisture levels, it looks like a proper clean up was not done. We've gone through a couple of drier change outs, and just received the oil analysis. It shows high levels of iron(bearings, rotors?) in the circuit that was repaired, and moisture still a little high. One more round of clean up should do, but the oil pressure fault is happening in both circuits. Not just the one that was repaired. A little extra info, this unit is under what appears to be a very l.ight load. Under full load conditions it will run approx. 10 minutes and be down 20 minutes each cycle. Any help will be greatly appreciated.

Jason

[oly77]

need more information''''' like suction and disch pressure, oil pressure, set point, stage fans, superheat and sub-cooling, compressor model #

[chiller32]

:confused: Gentlemen,
I've got a customer with a YCAS0130EC46YFADBX that will lock out on a "Low Differential Oil Pressure" fault. Only in low ambient conditions (25 degrees and below) will this happen. The barrel on this unit burst and was replaced last year, by another contractor. From moisture levels, it looks like a proper clean up was not done. We've gone through a couple of drier change outs, and just received the oil analysis. It shows high levels of iron(bearings, rotors?) in the circuit that was repaired, and moisture still a little high. One more round of clean up should do, but the oil pressure fault is happening in both circuits. Not just the one that was repaired. A little extra info, this unit is under what appears to be a very l.ight load. Under full load conditions it will run approx. 10 minutes and be down 20 minutes each cycle. Any help will be greatly appreciated.

Jason

not to sound to simple but.

1)what is the oil level in the oil separator?
2)what is the oil diff pressure?
3)when was the last time the oil filter was changed?

[mikelcs]

any foaming? crankcase heater o.k.? end bell superheat o.k.?

[pa2jonah]

I'm making a trip with my tech sometime next week to investigate further, more info will follow.

[chiller32]

from the IOM

Low Oil Differential Pressure Cutout:
The Low Oil Pressure Differential Safety assures the
compressor receives proper lubrication by monitoring
the differential between oil pressure returning to the
compressor and suction pressure. Lack of a differential
indicates that the compressor is not pumping and no oil
is being pumped through the compressor to lubricate
the bearings and rotors.

This type of oil failure will not be picked up by the
High Oil Differential Safety since no flow will cause
the differential through the oil piping to drop to zero.

EXAMPLE:
For ambients above 50°F (10°C), the Low Oil Differential
Safety is activated after 1 minute of compressor
operation when the oil pressure differential must be
greater than 10 PSID (.7 bar). After 2 minutes it must
be greater than 20 PSID (1.4 bar); after 3 minutes, 30
PSID (2 bar); after 4 minutes, 40 PSID (2.7 bar); and
from 5 minutes of operation and onwards, oil pressure
must remain higher than 50 PSID (3.4 bar) or the system
will be shut down. For lower ambients, the linear
ramp times are as follows:
AMBIENT TEMP RAMP TIME
>50°F (10°C) 5 Minutes
>45°F (7°C) 6 Minutes
>40°F (4°C) 7 Minutes
>35°F (2°C) 8 Minutes
>30°F (-1°C) 9 Minutes
<=30°F (-1°C) 10 Minutes

[pa2jonah]

A little update info here. Oil filters have now been changed on both circuits. Oil levels have been adjusted. It appears that most of these alarms have gone away now, but we are still getting the occasional alarm, mostly at night (low ambient) Here are some of the numbers from the last shutdown:

H2O LT- 70.1 degrees
RT- 74.4 degrees
Set point-70.0

Amb. Temp- 63.9

Run Time 12 mins 15 secs
55 amps 48% FLA

Oil press- 156 psi
Suction Press- 107 psi
Disch Press- 167 psi
Oil Temp- 103.6 degrees
Suction Temp- 71.4 degrees
Disch Temp- 135.2 degrees

Sat suction- 63.2
superheat- 8.2
Sat disch- 89.7
Disch S/H- 45.6

Slide Valve- Step 45
L/L Solenoid- On
Fan- Stage 2
Comp Heater- Off
Wye-Delta- On

If anybody has any ideas, I'd appreciate them.

:confused:

[chiller32]

A little update info here. Oil filters have now been changed on both circuits. Oil levels have been adjusted. It appears that most of these alarms have gone away now, but we are still getting the occasional alarm, mostly at night (low ambient) Here are some of the numbers from the last shutdown:

H2O LT- 70.1 degrees
RT- 74.4 degrees
Set point-70.0

Amb. Temp- 63.9

Run Time 12 mins 15 secs
55 amps 48% FLA

Oil press- 156 psi
Suction Press- 107 psi
Disch Press- 167 psi
Oil Temp- 103.6 degrees
Suction Temp- 71.4 degrees
Disch Temp- 135.2 degrees

Sat suction- 63.2
superheat- 8.2
Sat disch- 89.7
Disch S/H- 45.6

Slide Valve- Step 45
L/L Solenoid- On
Fan- Stage 2
Comp Heater- Off
Wye-Delta- On

If anybody has any ideas, I'd appreciate them.

:confused:

Why are you running a 70deg chill water setpoint? is this a process cooling aplication?

[pa2jonah]

Yes, it is process cooling.

[dgruber]

Hi Suction
Low Head

That's my first observation.

[klove]

Your whole problem is in the 70* setpoint. That's not allowing the suction temp/pressure to pull down, so in cool ambient conditions, you're never making differential. The slightest amount of sensor error will shut you down even earlier. The one thing that I did notice was the 8* superheat. It may be possible to adjust it up (15* if an exv, 18*+ on a txv) and that will raise your oil to suction diff. Also sounds like your condenser fans are at the low end of their "on" pressure. If you have the software to reset your fan pressures, it will probably satisfy your problem. If not, about the only thing you can do is either talk the York factory into burning you a special eprom to get you past this (good luck with that), or you can put your own cycling devices on the fans. Of course, you could always just lower the setpoint...............................

[dgruber]

Quick thought, have you checked out the compressor crankcase heater to make sure it is working properly?

This is a old thread I dug up doing a search on other issues. Sorry to have overlooked the posting dates of 2007.

Please disregard my posting to this issue!

[pa2jonah]

Gentlemen... Thanks for the replies, the problem has been resolved (about two years ago... If you'll notice the thread date)

klove... You are right on. York couldn't help with a custom EPROM. They had the contract at this place for four years and couldn't resolve the issue.

I finally installed a drive on the lead condensor fans to stabilize the pressures in lo-ambient conditions. We have not had an alarm in two years. "Field engineering" ; )

Gotta love it!

[klove]

I hate when that happens................(especially to me)