HELP! LWT SENOR FAULT (but sensor is OK) on York millenium recip chiller R22

[eskimko]

Dear all,

I need some advise regarding problem I have encountered this week


Water chiller
YORK INTERNATIONAL LTD
MODEL: YCA J87 SU7G Si 50174
SERIJA: No 14041
Year of manufacture: 1997.

Consist of 2 indipendent refrigeration circuits, refrigerant R22, TEX valves,
1 st compressor 8 cylinders YORK JH 833-S50 46S (no GGER 014 969) P=93 KW
malufuncioned
+
2 nd compressor BITZER 8FC 70.2 with 2 pcs of capacity regulators 100%, 75%, 50%, 0% working.



DIP SWITCH
X□1
X□2
□X3
OPEN X□4
□X5
X□6
□X7
□X8

X – CLOSE



HISTORY of alarm is as follows
HISTORY
SYS 2 COMP ON
SYS 2 MOTOR AMP 66 AMPS
OIL TEMP 57
SYS 2 4,67 BAR SUCTION
SYS 2 15,14 BAR DISCHARGE
SYS 2 OIL PRESSURE 2,86
SYS 2 LIQ LINE ON
SYS 2 RUN PERMISIVE ON
SYS 2 LOADING STAGES 3
SYS 2 COND FANS 1
WORK TIME 2 MIN 6 SEC
PES EQ VALVE
LWT 20.8 °C
LOW WATER CUTOUT 2,2 °C

SET POINT TEMP 4 °C
LOW AMB CUT OUT – 3.9 °C
LOW PRESSURE CUTOUT 3.1
LEAD SYSTEM 2
LOCAL REMOTE SETINGS REMOTE
COOLING RANGE 4,0 TO 5,1

we succeed to force Bitzer compressor to work 50% of capacity, and then we don't have problem with this LWT protection. It looks that it can't work when temperature difference between LWT and set point is too high.

We also succeed to put it operate when we put LWT probe in bottle of cold water 6 *c, problem is that LWT probe is also and antifrost probe!

Is it possible to change some parameters of factory set values condensation temp, condensation band etc?

Any ideas.
Thanks in advance...

[install monkey]

check your flow rates throught the evap, check theres no air in the top of the evap(water circuit)

[eskimko]

Water flow is ok. There is no air in installation. Flow switch is Ok too. I think that problem is related to processor Millenium. When we put LTW probe in bootle of cold water for simulating water temperature of 5 *c, we succeed to force Bitzer compressor to work on full power of 100% , and to reach setted temperature. After reaching it (setted temperature) we put probe back in water outlet probe on exit of evaporator and system works ok. If we switch it off and let temperature in system to rise to 20 *c, and then put it on again, compressor 2 will work 2 min and trip off with message
SYS#1 SYS SWITCH OPEN
SYS#2 LWT SENOR FAULT !!!!!!!!!!!!!! LWT is measuring 20 *c in this moment, and LWT is regulation and antifrost probe . It looks that Millenium have some problem with overshooting temperature protection.

[install monkey]

http://www.mediafire.com/view/?2l7yqke2asukang
http://www.mediafire.com/view/?bd2zlhzc88j45i1
bit of literature for you

[stufus]

Not 100% about your model but load limiting is a common scenario on chillers .
When the water temp is high it wont allow system to operate at full capacity but when the water temperature returns within the operating envelope the system will load up as normal.
Cheers
Stu

[paulg88]

Seems by looking at olders posts on this site that you're not the first to come across this problem. It seems they won't run once they hit 20 degrees... I've never seen this as the chillers I've worked on always kept within design temperatures. If your set point is 4 degrees, what's allowing it get to 20? Overloaded, or chiller switching off due to bms or other reasons?...

[al]

These early chillers measured LWT sensor and i think suction pressure or some such, basic answer is not to let the water temp rise to 20c, bring chiller on earlier or enquire about getting the eeprom upgraded. If the fault has only just appeared then check refrigerant charge in both circuits.

al

[eskimko]

Thanks install monkey,

but I already had these documents, and they haven't helped me. All is according to manual but I have LTW probe fault on system 2 (one with Bitzer compressor), system 1 is disabled (one with failed York compressor). When I disconnect LWT probe from system I recive LOW WATER TEMPERATURE MESSAGE *because value of LWT becomes -12,7 *c.

[eskimko]

Heating load of system it too high (cooled water is supplying 3 pcs of climatisation chambers) and Bitzer couldn't reach set point (of 7 *c) without YORK compressor. But Bitzer should work alone, and instead i have LWT sensor fault alarm activated, even if it is measuring 20 *c?

[Grizzly]

Just a guess!
Have you tried raising the setpoint and as the temp comes down you can drop it proportionally.

That way you may at least work out what settings you can run just the single Bitzer comp.
Which by the way implies that someone had already bodged the chiller.
Grizzly

[redroge]

As others have said these chillers will throw up a fault if the water temp is to high and restrict the loading.Ive also had dodgy sensors giving false readings and some coming up with a fault due to moisture in the sensor, try swopping the sensors and check they are giving the correct reading.

[paulg88]

To be honest, I think your only solution is to get the other half of your chiller fixed or replace the lot. Because there's only so long the bitzer will last being forced to work outside the chillers design temperatures...

[eskimko]

Yes, we can make it work when we decrease difference between setpoing and temperature measured by LWT (leaving water probe). Example LWT=20 *c and set setpoint to 19 *c and when we reach 19 *c on LWT to set up setpoint on 18 *c, then chiller works ok with 50 % capacity but cooling is slow and poor. As soon as we increase difference between setpoint and LWT (LWT 18 and setpoint to 7 *c) compressor starts working with 100% of capacity, and then it LWT sensor fault occurs, which require manual reset. It looks like we will need to remanufacture YORK compressor JH 833-S50 46S. Does someone have instruction for remanufacturing this compressors?

[al]

The compressor is fairly easy to rebuild on site, just need to know what is wrong with if first. Second option is to remove and send to a compressor rebuilder, if you need a site visit just let me know!!

al