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Thread: high coldroom temperature
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05-04-2011, 02:42 PM #1
high coldroom temperature
Hi Guys,
I have a 2 forced fan evaporator.Client stopped equipment for a month and when started up did not go down to -18 degrees celcius but remained to -2 degrees.I asked to turn off,and started it myself again.R404A.I read the following.
Ambient temperature 22.3 celcius.
Suction pressure 22 psig/ 1.5B
Discharge pressure 175psig/11.9B
Liquid line pressure 175 psig/11.9B
Thermometre readings.
After half hour running with sight glass clear and same pressures.
Suction temp 3.8 celc
Discharge temp 65.6 celc
Liquid line temp 38.5 celc.
Air off condenser fans 26.4 celc,entering 22.3 celc.
Air off evaporator fan/s -1 deg celc.
Room temperature -1 celc.
Inspection of txv having apartial frosting of evaporator.
What can be the reason of not getting the temperature down.I asked client to await till tomoroow morning and recheck temperature.
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05-04-2011, 04:47 PM #2
Re: high coldroom temperature
How long does the room normally take to pull down to temperature?
Brian - Newton Abbot, Devon, UK
Retired March 2015
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05-04-2011, 06:26 PM #3
Re: high coldroom temperature
Replace the refrigerant with a virgin one.
I have seen this hapening a few times. The best is to use 507.
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05-04-2011, 07:14 PM #4
Re: high coldroom temperature
This is the first time being on this plant,but left it working for 2 hours and did not drop below -2 celc from +8 celc.
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05-04-2011, 07:44 PM #5
Re: high coldroom temperature
if u have a back pressure of 1.5 Bar thats very low pressure whats is your coil temp?
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05-04-2011, 08:57 PM #6
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Re: high coldroom temperature
Suction pressure of 1,5 bar is -25°C
Suction temperature is 3,8°C! Where is it measured?
At -2°C coldroom temperature evaporation temperature should be -12°C to -17°C.
Liqud line pressure 11,9 is 26°C condensation. Entering air is 22,3°C. Condensation should be at least 32-35°C.
Liquid line temperature is 38,5°C. That mean no subcooling.
You are probably short of gas!
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05-04-2011, 11:58 PM #7
Re: high coldroom temperature
If you are short of gas so probably the compressor or the group of compressors is working at low partial capacity. Kerrcell do you confirm that?
OR only remains the two low pressure components of blend refrigerant (the R134a and the R143a) the high pressure component (R125) was gone.To make progress is never good enough, I want to do better and better and better
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06-04-2011, 12:06 PM #8
Re: high coldroom temperature
Hi guys,
I read suction temperature at close to compressor,not in the evaporator.Did not take the reading inside the evaporator! I did suspect that charge is low but obviously one cannot just start filling up with gas and then will find that has to take agaain part of it away if not in full ! This morning called the client and he said that during the night temperature dropped to -5,not more.The fact that the evaporator is partially frosted,drives me to lach of charge.Will recheck with client later today,if temperature,still the same,will collect what is in system.Then evacuate and refill by new gas R404A.
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06-04-2011, 01:48 PM #9
Re: high coldroom temperature
What's the % compressor capacity? Also if there is some kind of obstruction on the suction pipe (suction filter dirty or a valve partially close) then that will cause the present effect because the evaporating temperature would be much higher and consequently less capacity.
To make progress is never good enough, I want to do better and better and better
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06-04-2011, 02:03 PM #10
Re: high coldroom temperature
The cold room was empty when is start to work ?
Best regards,
HVAC - service technician
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06-04-2011, 08:46 PM #11
Re: high coldroom temperature
Yes the cold room was empty.I think it takes longer to drop down the temperature.Could not get in touch with client to confirm temperature but will update tomorrow.Thanks for now
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07-04-2011, 02:58 PM #12
Re: high coldroom temperature
Guys last night we had a total power cut whole country,will update tomorrow with temperature.
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07-04-2011, 03:57 PM #13
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08-04-2011, 12:38 AM #14
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08-04-2011, 07:29 AM #15
Re: high coldroom temperature
Morning Guys,
It seems all getting to the better,reading a temperature of -9 celcius.Cannot figure out what happened.I called on phone,did not visit back.I will leave it as it is for the moment and recheck.
Thanks for now.
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08-04-2011, 10:11 AM #16
Re: high coldroom temperature
If the cold store is empty, no in/out of product it is strange that the cold store takes to long down the temperature.
How much m3 have the cold store? What kind of insulation is applied on the cold store?To make progress is never good enough, I want to do better and better and better
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09-04-2011, 09:40 PM #17
Re: high coldroom temperature
The cold room is small.Measuring 8 by 8 by 7 feet high.Now temperature is -14 degrees celcius.It is old and so the insulation been never changed since.Coldroom been running around 9 years.But the compressor was changed around 4 years ago.The condenser coil has an area that is very corroded,as they washing it with tap water frequently to cool down in summer peaks !! Best thing to leave it running and see to what temperature it can drop best ! I thing there was a messup in this coldroom.
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10-04-2011, 02:48 AM #18
Re: high coldroom temperature
hmm...when the cold room be working normally with inlets and outlets of product I doubt it will do a good job. Let see what it happen and then keep us informed.
To make progress is never good enough, I want to do better and better and better
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10-04-2011, 09:21 AM #19
Re: high coldroom temperature
Very important parameter you didn't gave us: SH of evaporator
It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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11-04-2011, 01:05 PM #20
Re: high coldroom temperature
Hi peter1,
Yes unfortunately did not take it.To tell you the truth,client did not bother as temperature got down more ,now reading -14 degrees celcius.He also started filling it up.He installed also plastic curtain as there not.He prefered to leave it as it is,so happy him,happy me.By the way he did not ask for bill !!!!!!!! So better keep expenses to the minimum.
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11-04-2011, 06:26 PM #21
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Re: high coldroom temperature
Why would he ask for a bill? It is your work and money and you need to give him a bill, if you wish to collect money for your service.
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12-04-2011, 05:28 PM #22
Re: high coldroom temperature
Yep,but it looks as if I did nothing to solve his problem ! Temperature gradually went down.So best thing is to add a little extra next time I visit on something.That's better.
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12-04-2011, 06:17 PM #23
Re: high coldroom temperature
yes, I agree we must know I to deal with the Clients...specially the one that are very "complicated".
To make progress is never good enough, I want to do better and better and better
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07-05-2011, 09:56 PM #24
Re: high coldroom temperature
i would just for argument sakes recover refrigerant replace liquid line drier, obviously pull full vac and recharge with virgin refrigerant.
at least this will rule out if you have lost part of refrigerant blend.
then start again if problem does persist at least you have ruled out a major possible fault.your only as good as your last job
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09-05-2011, 07:39 AM #25
Re: high coldroom temperature
All clients are complicated .................