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Great problem........
We are using HITACHI chiller Model No.: RCUP-46AUZ,
To day when we run the system we find some abnormality, no cooling at all! chilled water inlet & outlet temp. is same. we measure subcool temp. its less then one & compare with previous discharge temp. it decrease nearly half (from 340PSI to 175PSI), then we try to measure suction pressure but we found lots of oil mixing with refrigerent like detergent shop bubble. We stop the chiller, what should be our steps now?
Note: Two days ago we change the chiller position and we run the unit today.
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Re: Great problem........
hi,
water is short cycling.you hve to ope up the barrel and c the partiton gasket is broken.
thanks,
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Re: Great problem........
Quote:
Originally Posted by
bmundoorkote
hi,
water is short cycling.you hve to ope up the barrel and c the partiton gasket is broken.
thanks,
no water in the line, its oil!
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Re: Great problem........
Not enough readings to help you properly. If it's like soap: liquid refrigerant has entered you oil and this is foaming up when you start up. Crankcase heater switched on long enough?
Evacuate once you compressor body with a recuperation station and pump it to the receiver. Measure crankcase temperature while pumping out and see if it drops in temperature, then you know if there was liquid.
If you worked on the machine and problems started afterwards, you must find reason what went wrong when you worked on that machine.
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Re: Great problem........
Quote:
Originally Posted by
Peter_1
Not enough readings to help you properly. If it's like soap: liquid refrigerant has entered you oil and this is foaming up when you start up. Crankcase heater switched on long enough?
Evacuate once you compressor body with a recuperation station and pump it to the receiver. Measure crankcase temperature while pumping out and see if it drops in temperature, then you know if there was liquid.
If you worked on the machine and problems started afterwards, you must find reason what went wrong when you worked on that machine.
Sir,
Our compressor model is semi-hermetic screw compressor 50ASCP-Z, I don’t think soap forming inside the line, its the compressor oil mixing with the refrigerant.
I am giving you all the data whatever i have:
Evap. Entering Water Pr. 48 PSIG
Evap. Leaving Water Pr. 30 PSIG
Ref. Discharge Pr. 1.20 MPa.
Ref. Suction Pr. 0.53 MPa.
Discharge Gas Temp. 43 deg. C
Suction Gas Temp. 11 deg. C
Water cooler inlet ref. gas temp. 8 deg C
Liquid ref. Temp. 320deg C
Chilled water inlet and outlet temp. 11 deg. C
Setting water temp. 7 deg. C
ON/OFF diff. 2 deg. C
Ambient temp. 30 deg. C
Note: All the data I found from the panel board and parallely there are another two chiller in that system.
Now I giving you the data I measured,
Suction pr. 80 PSI, Discharge pr. 175 PSI, Subcooling temp. 0.5 deg C.
Condenser inlet and outlet air temp. 30 and 31 deg. C
Compressor amp. 50.3, no fault showing in the panel what so ever!
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Re: Great problem........
Pressures don't mean anything without knowing refrigerant in unit.
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Re: Great problem........
Quote:
Originally Posted by
nike123
Pressures don't mean anything without knowing refrigerant in unit.
Sorry, I just miss.....
Its R407C
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Re: Great problem........
check water filter (blocked) ??
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Re: Great problem........
Quote:
Originally Posted by
frederik79
check water filter (blocked) ??
We checked it at first......
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Re: Great problem........
Hi there,
With the figures you gave, it seems that you have liquid flood back.
At suction pressure R407C 's dew point is around 10°C and your suction gas temp. is 11°C. This means liquid flood back. When this happens then you get a lot of foaming in the crankcase.
Check if you have enough water flow.
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Re: Great problem........
Quote:
Originally Posted by
lana
Hi there,
With the figures you gave, it seems that you have liquid flood back.
At suction pressure R407C 's dew point is around 10°C and your suction gas temp. is 11°C. This means liquid flood back. When this happens then you get a lot of foaming in the crankcase.
Check if you have enough water flow.
Today I observe:
Water cooler inlet ref. gas temp. 1.5 to 2.5 deg C
Comp. Suction temp. 5.2 Deg C
Why this temp. is so low? Still no cooling effect!
Measured Value:
Suction Pressure55PSISuction Temperature5.2CDischarge Pressure190PSIDischarge Temp33.5CPressure after TEV 88PSITemperature after TEV1.5 to 2.5CTempe. After compressor (Discharge line)58CTemp. of exhaust temp.39.3C
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Re: Great problem........
Quote:
Originally Posted by
nike123
Pressures don't mean anything without knowing refrigerant in unit.
Model Hitachi RCUP46AU(Z)
Date: 01.06.10
Parameters at 12:30 PM ,12:40 PM, 12:50 PM, 1:00 PM
Suction Pressure (Mpa): 0.55, 0.44, 0.41, 0.43
Discharge Pressure MPa: 1.72, 1.83, 1.84, 1.38
Discharge Temp Deg C: 73, 80, 79, 79
Liquid ref. temp. Deg C: 46, 48, 48, 49
Water cooler inlet Rfgt. Gas temp Deg C: 11, 8, 7, 6
Suction Temperature Deg C: 18,13,9,7
Chilled water inlet temp. Deg C:25,22,20,18
Chilled water outlet temp. Deg C: 24,21,19,17
Amp. taken by Chiller: 68 amp,67.8,67.5,68
Environmental temp. Deg C: 36,35,35,36
Note: Rated Chiller Amp. 76 & Refrigerent use R407C
Every time chiller is tripping arrived this condition with the fault of 13 13, it indicate that cmpressor is stop on freeze protection thermostat, we check all the temp. & presser sensor, solenoid valve of comp. thermistor, chilled water flow, air in water ckt. all are ok.
Any Help?
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Re: Great problem........
what type of evaporator is it? Plate heat exchanger or shell and tube?
It would appear that there is a lack of heat exchange occuring, if it is a shell and tube it is possible that the refrigerant is bypassing the evaporator via. a split end gasket, allowing low pressure liquid refrigerant through to the suction. I have had a similar problem in the past but my concern was with the low superheat. The compressor turned out to have the wrong oil, mineral instead of synthetic. This caused waxing on the evaporator tubes which reduced the heat exchange and superheat.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Model Hitachi RCUP46AU(Z)
Date: 01.06.10
Parameters at 12:30 PM ,12:40 PM, 12:50 PM, 1:00 PM
Suction Pressure (Mpa): 0.55, 0.44, 0.41, 0.43
Discharge Pressure MPa: 1.72, 1.83, 1.84, 1.38
Discharge Temp Deg C: 73, 80, 79, 79
Liquid ref. temp. Deg C: 46, 48, 48, 49
Water cooler inlet Rfgt. Gas temp Deg C: 11, 8, 7, 6
Suction Temperature Deg C: 18,13,9,7
Chilled water inlet temp. Deg C:25,22,20,18
Chilled water outlet temp. Deg C: 24,21,19,17
Amp. taken by Chiller: 68 amp,67.8,67.5,68
Environmental temp. Deg C: 36,35,35,36
Note: Rated Chiller Amp. 76 & Refrigerent use R407C
Every time chiller is tripping arrived this condition with the fault of 13 13, it indicate that cmpressor is stop on freeze protection thermostat, we check all the temp. & presser sensor, solenoid valve of comp. thermistor, chilled water flow, air in water ckt. all are ok.
Any Help?
What is this marked with red?
Is this relocated chiller which run fine before relocation?
How did you checked water flow? Did you actually measured flow? How much is it?
From numbers, you have no subcooling at all. It look like you are short of gas!
http://i45.tinypic.com/wgqixz.jpg
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Re: Great problem........
Quote:
Originally Posted by
mgtet
what type of evaporator is it? Plate heat exchanger or shell and tube?
It would appear that there is a lack of heat exchange occuring, if it is a shell and tube it is possible that the refrigerant is bypassing the evaporator via. a split end gasket, allowing low pressure liquid refrigerant through to the suction. I have had a similar problem in the past but my concern was with the low superheat. The compressor turned out to have the wrong oil, mineral instead of synthetic. This caused waxing on the evaporator tubes which reduced the heat exchange and superheat.
No its a plate type heat exchanger.
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Re: Great problem........
Quote:
Originally Posted by
nike123
What is this marked with red?
Is this relocated chiller which run fine before relocation?
How did you checked water flow? Did you actually measured flow? How much is it?
From numbers, you have no subcooling at all. It look like you are short of gas!
http://i45.tinypic.com/wgqixz.jpg
Yes Sir, You are right, but the previous position was so congested for the chiller that condenser air flow was terribly bad.
Now we charge the system, as supplier told us to do that, now Discharge pressure avg. is 1.84 MPa, Suction Pr. avg. is 0.38 MPa. Discharge gas temp. 65 C, Suction gas temp. 12 C, Water cooler inlet ref. gas temp. 5 C, Liquid ref. temp. 48 C, Chilled water in and out temp 17 & 16, ambient temp. 28 C. Not sufficient cooling is not it?
Sir, Second & third step of Result, I did not understand?
Actually we have three Hitachi chillers all are in parallel, others are running ok, so i thought water flow is ok! All water inlet pressure is same.
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Re: Great problem........
We need full readings. Your measurements are incomplete!
Evap air/water in temp
Evap air/water out temp
Low side pressure or saturation temp
Suction line temp at evap outlet!!!
Suction line temp at compressor inlet
Cond air/water in temp
Cond air/water out temp!!!
High side pressure or saturation temp
Liquid line temp at receiver or condenser outlet!!!
Liquid line temp at TXV inlet!!!
The more information provided the more accurate the diagnosis.
Check fan rotation direction.
You still don't have enough subcooling.
Without knowing condenser air on and off temperatures we cannot see what condenser is doing!
TD of evaporator is evaporator water in temperature minus R407 mean evaporation saturation temperature (because of temperature glide it is used mean evaporation temperature). For example:
Twi= 17°C
(R407C at 0,38Mpa has 1,5°C dew point and -5°C bubble point therefore mean evaporation temperature is -5°C +1/2 od 6,5°C glide = -1,75°C)
Te=-2°C
Twi-Te=17 - (-2)= 19K
Evaporator aproach is difference between evaporator water leaving temperature and evaporation saturation mean temperature.
A higher than normal evaporator approach can indicate an undercharge.
Similar is for condenser side.
Condenser TD is condenser mean saturation temperature minus condenser air in temperature
Condenser aproach is is condenser mean saturation temperature minus condenser air off temperature.
High condenser approach mean dirty condenser. High condenser delta t mean low air flow.
I made some mistakes in my table. Now it is corrected.
http://i49.tinypic.com/17v4hw.jpg
Your lack of any subcooling and high evaporator approach indicate that you are still short of refrigerant.
recover and charge by weight, then take a new full set of readings as listed above.
I asked what is this:
Water cooler inlet Rfgt. Gas temp Deg C
You did not answered.
If it is what is written than that reading is useless.
We cannot conclude anything from reading temperature of pipe between TXV and evaporator.
What we need is temperature and pressure of pipe 10-15 cm before expansion valve. That tell us if we have subcooled liquid before TXV.
Your evaporator water flow should be measured with flow meter. Pressure at inlet doesn't mean anything.
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Re: Great problem........
Quote:
Originally Posted by
nike123
We need full readings. Your measurements are incomplete!
Evap air/water in temp
Evap air/water out temp
Low side pressure or saturation temp
Suction line temp at evap outlet!!!
Suction line temp at compressor inlet
Cond air/water in temp
Cond air/water out temp!!!
High side pressure or saturation temp
Liquid line temp at receiver or condenser outlet!!!
Liquid line temp at TXV inlet!!!
The more information provided the more accurate the diagnosis.
Check fan rotation direction.
You still don't have enough subcooling.
Without knowing condenser air on and off temperatures we cannot see what condenser is doing!
TD of evaporator is evaporator water in temperature minus R407 mean evaporation saturation temperature (because of temperature glide it is used mean evaporation temperature). For example:
Twi= 17°C
(R407C at 0,38Mpa has 1,5°C dew point and -5°C bubble point therefore mean evaporation temperature is -5°C +1/2 od 6,5°C glide = -1,75°C)
Te=-2°C
Twi-Te=17 - (-2)= 19K
Evaporator aproach is difference between evaporator water leaving temperature and evaporation saturation mean temperature.
A higher than normal evaporator approach can indicate an undercharge.
Similar is for condenser side.
Condenser TD is condenser mean saturation temperature minus condenser air in temperature
Condenser aproach is is condenser mean saturation temperature minus condenser air off temperature.
High condenser approach mean dirty condenser. High condenser delta t mean low air flow.
I made some mistakes in my table. Now it is corrected.
http://i49.tinypic.com/17v4hw.jpg
Your lack of any subcooling and high evaporator approach indicate that you are still short of refrigerant.
recover and charge by weight, then take a new full set of readings as listed above.
I asked what is this:
Water cooler inlet Rfgt. Gas temp Deg C
You did not answered.
If it is what is written than that reading is useless.
We cannot conclude anything from reading temperature of pipe between TXV and evaporator.
What we need is temperature and pressure of pipe 10-15 cm before expansion valve. That tell us if we have subcooled liquid before TXV.
Your evaporator water flow should be measured with flow meter. Pressure at inlet doesn't mean anything.
Sir, I am out of plant for two days training program. I will gave you all the data on 06/06/2o1o.
Water cooler inlet temp. ? its the liquid ref. temp enter into the HE.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Sir, I am out of plant for two days training program. I will gave you all the data on 06/06/2o1o.
Water cooler inlet temp. ? its the liquid ref. temp enter into the HE.
At the enter of HE is liquid gas mixture after TXV and that temperature is of no use (it is not saturated temperature) because gas is not there because of evaporation but because of pressure drop at TXV.
We need liquid line temperature 15 cm before expansion valve (to see if there is pure liquid refrigerant at TXV inlet) and we need pipe temperature after HE where TXV bulb is placed (to find evaporator superheat and proper TXV operation).
Take your measurement with accurate calibrated service instrument and not with unit sensors. You could give unit sensor readings only when you check wit accurate service instrument that their readings are accurate.
Take your reading only when capacity control is at 100%
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Re: Great problem........
Quote:
Originally Posted by
nike123
At the enter of HE is liquid gas mixture after TXV and that temperature is of no use (it is not saturated temperature) because gas is not there because of evaporation but because of pressure drop at TXV.
We need liquid line temperature 15 cm before expansion valve (to see if there is pure liquid refrigerant at TXV inlet) and we need pipe temperature after HE where TXV bulb is placed (to find evaporator superheat and proper TXV operation).
Take your measurement with accurate calibrated service instrument and not with unit sensors. You could give unit sensor readings only when you check wit accurate service instrument that their readings are accurate.
Take your reading only when capacity control is at 100%
.
Sir,
How can I attach a Excel paper? or give me your mail ID that I can mail you!
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Re: Great problem........
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1 Attachment(s)
Re: Great problem........
Sir,
Following data I measured, we check all the pr. & temp. sensor so you can trust on my data.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Sir,
Following data I measured, we check all the pr. & temp. sensor so you can trust on my data.
What did you done on chiller between last posted measurements and this measurements? Your discharge pressure and amperage is significantly dropped with same ambient temperatures since last measurement.
Do not "throw" data at us without explaining what is done between measurements. Remember, we are not there.
I see now that condenser is doing OK! That mean that evaporator is picking some heat. It looks like evaporator having some serious overflow!
Edit: I made some mistakes in calculation for above sentence. It does not look OK and it does not picking much heat.
Did you measured water flow?
Your results are not good. Formulas are wrong. Upload your excel file in order to see what is wrong with formulas.
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Re: Great problem........
hi basheer,what is comp.RLA AND current running ampere.you are sure compressor is full load.this is screw,so it may work under 10% capacity.have you check the loading unloading.waiting your replay.
Moideen-dubai:)
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1 Attachment(s)
Re: Great problem........
Dear Sir,
After that measurement we recharge the chiller and after that we observe compressor is taking more then 100 amp (but its actually 76 amp rated), we discharge some refrigerant and its still taking more then 90 amp, then we need to close for that day (office time closed). And again next morning we measured the value and find the attached file data.
In-between this we checked all the sensors, valve and chilled water flow rate of evaporator (approximately 30 m3/hr).
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Re: Great problem........
Quote:
Originally Posted by
moideen
hi basheer,what is comp.RLA AND current running ampere.you are sure compressor is full load.this is screw,so it may work under 10% capacity.have you check the loading unloading.waiting your replay.
Moideen-dubai:)
Yes, we check loading/unloading of compressor.
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Re: Great problem........
Your txv orifice is fixed or replaceable? Your evaporator approach temp. Is very high. this clear evidence that there is not take place heat transfer. I think your evaporator is fouled. check your evaporator individually.:confused:
Moideen-Dubai
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Re: Great problem........
Quote:
Originally Posted by
moideen
Your txv orifice is fixed or replaceable? Your evaporator approach temp. Is very high. this clear evidence that there is not take place heat transfer. I think your evaporator is fouled. check your evaporator individually.:confused:
Moideen-Dubai
Its an Electronic Expansion Valve with modulating control.
If the problem with HE then we are in big trouble because just few days ago we clean the water line.
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Re: Great problem........
Are u sure u have flow through the evap? Flow and pressure not the sane thing.
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Re: Great problem........
Quote:
Originally Posted by
ktm
Are u sure u have flow through the evap? Flow and pressure not the sane thing.
Yes, we measured the flowrate before and after HE.
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1 Attachment(s)
Re: Great problem........
Check that you have correct water flow direction. It must be counter flow with refrigerant.
Attachment 3554
http://i46.tinypic.com/2cmt201.jpg
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Re: Great problem........
Quote:
Originally Posted by
nike123
Check that you have correct water flow direction. It must be counter flow with refrigerant.
But Sir, it’s installed correctly as we installed othr chiller and as per manual.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Dear Sir,
After that measurement we recharge the chiller and after that we observe compressor is taking more then 100 amp (but its actually 76 amp rated), we discharge some refrigerant and its still taking more then 90 amp, then we need to close for that day (office time closed). And again next morning we measured the value and find the attached file data.
In-between this we checked all the sensors, valve and chilled water flow rate of evaporator (approximately 30 m3/hr).
Sir, If possible correct my formulas in the attached file, and how can I use it for fault finding?
Its difficult for me, because of my little knowledge, I have all the charts, tables collecting from this forum but some data is not matching with your given table and most of the data I am not finding from the chart, in one wards it’s not clear to me (result column of your chart).
I understand you are too busy and sometimes you may angry with my questions!
I will love to thanks you again……..
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
But Sir, it’s installed correctly as we installed othr chiller and as per manual.
Describe how did you measured water flow?!
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Sir, If possible correct my formulas in the attached file, and how can I use it for fault finding?
Its difficult for me, because of my little knowledge, I have all the charts, tables collecting from this forum but some data is not matching with your given table and most of the data I am not finding from the chart, in one wards it’s not clear to me (result column of your chart).
I understand you are too busy and sometimes you may angry with my questions!
I will love to thanks you again……..
I made correct table and attached in my previous post.
Read carefully what I described how to get results in my previous posts in this thread and check formulas in that excel file result fields. Than ask what is not clear to you.
http://i46.tinypic.com/rmp4yf.jpg
Check this page:
http://www.air-conditioning-and-refr...er-system.html
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Re: Great problem........
Quote:
Originally Posted by
nike123
Describe how did you measured water flow?!
Oh! Sorry when I am writing my next question you already answer it.
For measuring the flow rate we use raw method, Q= volume/time, as we have no flow meter for this purpose.
Take a drum with known volume and we take time to fill it.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Dear Sir,
After that measurement we recharge the chiller and after that we observe compressor is taking more then 100 amp (but its actually 76 amp rated), we discharge some refrigerant and its still taking more then 90 amp, then we need to close for that day (office time closed). And again next morning we measured the value and find the attached file data.
In-between this we checked all the sensors, valve and chilled water flow rate of evaporator (approximately 30 m3/hr).
Here it is not clear what you done. If you removed refrigerant and measured 90A than closed for that day, how than that next measurements of current are with low amperage from 45 to 60 A and not 90A as you measured day before, without fiddling with refrigerant charge again or with unloading and loading of compressor. Since that chiller is with continuous capacity control, how did you force it to stay at full loading?
If you done something in between 9 and 12 hr when these measurements in excel table are taken, than you should say what is done in what time.
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Re: Great problem........
Quote:
Originally Posted by
Bashir01219
Oh! Sorry when I am writing my next question you already answer it.
For measuring the flow rate we use raw method, Q= volume/time, as we have no flow meter for this purpose.
Take a drum with known volume and we take time to fill it.
With that method you are not taking in account all restrictions in system since you changed water path to measure flow. Therefore, measured flow doesn't represent actual flow. You need ultrasonic flow meter or pressure differential meter on flow measuring valve with known kv.
Is that flow constant or you having regulating devices which my change flow?
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Re: Great problem........
Can the OP stop the chiller & open the evaporator? Take some pictures of the evap & let us have a look.
Your evap is clearly not picking up heat, for some reason. I've seen comments regarding either water, or refrigerant bypassing - or, incorrect pipework.
Do you have an idea of what the correct refrigerant charge is for your system? If so, what is your present charge?
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Re: Great problem........
Quote:
Originally Posted by
nike123
Here it is not clear what you done. If you removed refrigerant and measured 90A than closed for that day, how than that next measurements of current are with low amperage from 45 to 60 A and not 90A as you measured day before, without fiddling with refrigerant charge again or with unloading and loading of compressor. Since that chiller is with continuous capacity control, how did you force it to stay at full loading?
If you done something in between 9 and 12 hr when these measurements in excel table are taken, than you should say what is done in what time.
When we measured 90Amp. then we only ran one chiller for total system, its a closed loop and nearly 3000 ltr water in the ckt, and again in the next morning when we measured the data another chiller of 90 ton was running with the system, may be its a cause or we have a leakage in the system that causes leaking of refrigerant which causes low amp. of the compressor in the next morning.