Carrier 30RBA Tripping

[R123]

M# 30RBA0705-0-3
S# 3507Q81294

This chiller is intermittently tripping on P06 "circuit B low saturated suction temperature". I've checked the chiller out completely and can't find any problems. The suction transducer and suction gas temperature sensor check out good. I checked out the EXV according to the book and it checks out good. I've also checked the electrical connections for the EXV and sensors. My superheat, subcooling, and EXV position looks good. All fans are working and coils just cleaned. The pump runs continuously and the water flow is correct (set for 10 degrees delta). Also, circuit A runs fine.

My readings are (with just circuit B running):
Entering Water Temp: 47.4
Leaving Water Temp: 44.7
OAT: 76
Saturated Condensing Temp: 108
Saturated Suction Temp: 34.9
Suction Gas Temp: 45.1
Superheat: 10.2
Subcooling: 17
Suction Pressure: 108
Discharge Pressure: 355
EXV Position: 42%


The chiller is also tripping on P97 "water exchanger temperature sensors swapped". There is no description on this alarm in the book, but I'm assuming it means the controller is seeing the entering water temperature sensor lower than the leaving water temperature sensor. Again, I don't see any problems with the water temp sensors and they check out good. I'm thinking that one of them is intermittently failing.

I've had the 'low saturated suction temp' alarm about 5 times now and the 'water exchanger temp sensors swapped' alarm twice now.

If anyone has any ideas, it would be much appreciated!

[BKS60]

DP ?
Also I have seen line voltage input power problems cause trips on flow alarms. I can't tell you why but when the power was corrected the problems went away!

[spinning wheel]

why is just B running, how many compressors are running at this time. the reason I am asking is if you are just running one circuit, then you are overloading the running circuit. you will get false trips because you are running very close to freezing on your sat evap temp. you need to take a DP across the barrel and get the correct flow reading, and if this is correct you need to check the cleanliness of your barrel tubes. sounds like you have a fouled tube issue due to the high approach on the cooler leaving to the sat refrigerant temp.

[R123]

why is just B running, how many compressors are running at this time. the reason I am asking is if you are just running one circuit, then you are overloading the running circuit. you will get false trips because you are running very close to freezing on your sat evap temp. you need to take a DP across the barrel and get the correct flow reading, and if this is correct you need to check the cleanliness of your barrel tubes. sounds like you have a fouled tube issue due to the high approach on the cooler leaving to the sat refrigerant temp.

B was only running because that was all that was being called for to maintain setpoint. Circuit A runs as needed and they rotate. Circuit A has 2 larger compressors, and Circuit B has 1 smaller compressor. At the time I took the readings, only the one compressor on circuit B was running. Since the evaporator is a dry expansion shell and tube type and has 2 circuits, and circuit A is considerably larger and was not running, I was thinking that was the cause of the higher approach. The flows are correct as I already checked that but I forgot to write down the DP. I will try to fully load the chiller tomorrow to see what the approach does.

[under pressure]

http://hvac-talk.com/vbb/showthread.php?t=720831


If in doubt, valve it out.........................

[Dallas Duster]

I agree with you on maybe your LWT sensor may be floating up. Just out of curiosity what is you MBB software version?

[Nuclrchiller]

http://hvac-talk.com/vbb/showthread.php?t=720831


If in doubt, valve it out.........................

I know where there was (still is?) an RTAA in this condition. In a facility that recycles paper into a product like egg crates used to be made of. Open sump chill water with the sump located under a section of the process line where there is shredded and mulched paper. I left before it was ever opened and verified. Sounds like this condition needs to be eliminated or verified in your case too.

[swamp]

M# 30RBA0705-0-3
S# 3507Q81294

This chiller is intermittently tripping on P06 "circuit B low saturated suction temperature". I've checked the chiller out completely and can't find any problems. The suction transducer and suction gas temperature sensor check out good. I checked out the EXV according to the book and it checks out good. I've also checked the electrical connections for the EXV and sensors. My superheat, subcooling, and EXV position looks good. All fans are working and coils just cleaned. The pump runs continuously and the water flow is correct (set for 10 degrees delta). Also, circuit A runs fine.

My readings are (with just circuit B running):
Entering Water Temp: 47.4
Leaving Water Temp: 44.7
OAT: 76
Saturated Condensing Temp: 108
Saturated Suction Temp: 34.9
Suction Gas Temp: 45.1
Superheat: 10.2
Subcooling: 17
Suction Pressure: 108
Discharge Pressure: 355
EXV Position: 42%


The chiller is also tripping on P97 "water exchanger temperature sensors swapped". There is no description on this alarm in the book, but I'm assuming it means the controller is seeing the entering water temperature sensor lower than the leaving water temperature sensor. Again, I don't see any problems with the water temp sensors and they check out good. I'm thinking that one of them is intermittently failing.

I've had the 'low saturated suction temp' alarm about 5 times now and the 'water exchanger temp sensors swapped' alarm twice now.

If anyone has any ideas, it would be much appreciated!

I had the exact problems, I ended up installing new temp sensors, and I also had a leak on one of manifold flanges. after repairing, and topping off sight glass, the problems went away

[2wings]

I've had to replace several Suction Temp Sensors, very intermitant, absolutely a weak link in these systems.

[IRWINDSOUZA]

I have a problem with the CIR A on the 30RBA unit, the EXV remains open 100% all the time, there is adequate refrigerant in the system, checked all the transducers and thermistors and found to be OK. Tested the EXV on test mode and it appears to be working OK on both 0% and 100%. As of now I dont have any answers to the problem. Appreciate if someone can give me some indicators for troubleshooting.

[Dallas Duster]

I have a problem with the CIR A on the 30RBA unit, the EXV remains open 100% all the time, there is adequate refrigerant in the system, checked all the transducers and thermistors and found to be OK. Tested the EXV on test mode and it appears to be working OK on both 0% and 100%. As of now I dont have any answers to the problem. Appreciate if someone can give me some indicators for troubleshooting.

And what did your thermistors say exactly?

[Gibbo]

Get some readings of A circuit under full load and compare with B circuit.
Are your B circuit readings at 100% if not do them again only full load readings will give you an idea whats happening.

Happy New Year to all.

[IRWINDSOUZA]

Was not sure about how much refrigerant in the system, hence recovered all the freon flushed with Nitrogen and vacuumed the entire system, checked for any leaks, found none. held the vacuum for almost 24 hours and did not find any change. Assumed that there is no leaks. Topped up the oil and charged the unit upto 31 Kgs (Full Charge 68 Lbs) as per the name plate details. Checked and confirmed the suction gas thermistor is working properly, found OK. Swapped the pressure transducers between CIR-A and CIR-B to ensure they are OK. Restarted the unit, and still found the CIR A EXV open full 100%. The readings obtained when all the 4 compressors were running are as follows. As soon as the water temperature reaches the set point, invariably both the compressors on CIR-A shutdown, and the compressors on CIR-B continue running

DPA : 2055 Kpa, DPB : 2710 Kpa
SPA : 637 Kpa, SPB : 783 Kpa

SCTA : 35.3°C, SCTB : 46.2°C
SSTA : -2.4°C, SSTB : 3.2°C
SGTA : 3.8°C, SGTB : 6.8°C
SUPA : 6.2°C ∆, SUPB : 3.5°C ∆
EXVA : 100%, EXVB : 56%
OAT : 25°C
EWT : 8.2°, LWT : 7.1°C
COOLING WATER SET POINT : 6.5°C

Still not sure where to look for the problems, appreciate if someone can help me out with this problem