Problem with chiller

[Bashir01219]

We are using HITACHI Chiller, Model No.: RCUP-46AU(Z). Refrigerent R 407 C.
Our main problem is the chiller section sometimes tripped and fault shows 13-13 Active of freeze protection by thermistr.
#Chilled water inlet temp. 10 Deg. C and outlet temp. 9 Deg. C.
#We check the thirmistor.
# Chilled water flow pressure is ok, and we also clean the evaporator (as described in manual) after the problem arrived.
# Purge air from the chilled water line.
Note: After cleaning the evaporator the chiller unit didnt tripped for a week, and after that it showing the same problem again.
What is the probable troubleshooting steps now...............?

[Brian_UK]

You say that the chilled water flow pressure is OK but is the flow rate correct?

Also you are only showing 1°C across the evaporator, not very much happening there is there?

[Bashir01219]

Sir,
Thanks for the replay..........
I have no idea how to measure flow rate across the evaporator, & most of the time chilled water inlet & outlet temperature difference is not less then 2 deg C.

[ref717]

this is unusual,temp. difference across the evaporator should be around 6-9 deg. Celsius.,Brian_UK is correct,check the chilled water flowrate,maybe you dont have enough water velocity in the evaporator.,or there is ice-build up in the evaporator coils,check also your expansion valve.

[Gary]

I would start with the piping. The water should enter the bottom of the evaporator and exit the top.

[Gary]

We are using HITACHI Chiller, Model No.: RCUP-46AU(Z). Refrigerent R 407 C.
Our main problem is the chiller section sometimes tripped and fault shows 13-13 Active of freeze protection by thermistr.
#Chilled water inlet temp. 10 Deg. C and outlet temp. 9 Deg. C.
#We check the thirmistor.
# Chilled water flow pressure is ok, and we also clean the evaporator (as described in manual) after the problem arrived.
# Purge air from the chilled water line.
Note: After cleaning the evaporator the chiller unit didnt tripped for a week, and after that it showing the same problem again.
What is the probable troubleshooting steps now...............?

Was there air in the chilled water line?

[Bashir01219]

The water should enter the bottom of the evaporator and exit the top. Yes our chilled water system line have the facility.

[sedgy]

hi bashir, also is the chiller very old?, have you inspected the chilled water strainer?

[Bashir01219]

we have strainer after pump but not before evaporator.

[Peter_1]

t...temp. difference across the evaporator should be around 6-9 deg. Celsius.,Brian_UK is correct,check the chilled water flowrate,maybe you dont have enough water velocity in the evaporator....

If you should have not enough waterflow,then you will see a big DT,
So in his case, waterflow is extremely high
Where is freeze protection measurement located exactly?

[Bashir01219]

How can we measure water flow? We can measure it through raw method, but is it error free.
Parallel we have another Trane chiller, and there is no problem.
And the position of the freeze protection sensor is chilled water outlet line.

[Gary]

If you should have not enough waterflow,then you will see a big DT,
So in his case, waterflow is extremely high
Where is freeze protection measurement located exactly?

Unless there is zero waterflow, in which case there should be zero dT.

[Gary]

Was there air in the chilled water line?

You missed this question.

[Gary]

Chilled water flow pressure is ok...

Ok is an opinion, not a pressure.

What is the pressure?

[Bashir01219]

Chilled water inlet pressure 4.8 Bar, & outlet pressure nearly 4.0 Bar.
There is no air in the chilled water line, we check the air venting line several times.
sometimes dT shows Zero, at the begining of the machine start.

[mad fridgie]

Hi, do you know what your suction pressure/temp.
Are you sure that the freeze sensor is in the water line, and not in a pocket in the evap.
My gut feeling is that your tubes are fouled, stopping heat transfer, but not enough to block the flow. causing a lower SST than normal
Mad F

[Gary]

What refrigerant is in the system?

When the system is running, what are the pressures, temperatures, subcooling, superheat?

When the system is off what pressure does it equalize at?

[Bashir01219]

Sir, Lots of question?
You know i am new in this line,

Refrigerant: R407C,
System need to run at 7.00 am to 8.00 pm (everyday).
Temp. at TXV valve 17 deg C, Evaporating pressure 95 PSI
Superheat temp. nearly 6 deg C.
Compresser discharge pressure 340 PSI,
Temperature leaving the condenser 53.1 deg C
So, subcool temp. 3 deg C.
Note: Parallel we have another Trane chiller.

[mad fridgie]

Sir, Lots of question?
You know i am new in this line,

Refrigerant: R407C,
System need to run at 7.00 am to 8.00 pm (everyday).
Temp. at TXV valve 17 deg C, Evaporating pressure 95 PSI
Superheat temp. nearly 6 deg C.
Compresser discharge pressure 340 PSI,
Temperature leaving the condenser 53.1 deg C
So, subcool temp. 3 deg C.
Note: Parallel we have another Trane chiller.

Good info, based upon this your water temp readings are wrong, your evap temp is higher than your water temp.

[Bashir01219]

when i got the readings, chilled water temp. was in inlet 15 deg. C, & outlet 14 deg. C.

[Gary]

when i got the readings, chilled water temp. was in inlet 15 deg. C, & outlet 14 deg. C.

Your readings are still wrong. What are you measuring temperatures with?

[Bashir01219]

From the panel i got the temp.