Cold storage for meat store problem

[hamza nawaz]

Hi dears,

I m Hamza from pakistan & working in a power plant as HVAC technician, some how we have a col storage of 4.0 ton capacity to maintain -18 celsius, the problem i've got that it didnot maintain TEMPRATURE TO -18 CELSIUS I HAVE CHECKED THESE ALSO can any 1 help what i do.
:> Suction pressure is 22 psi at room temprature of -12 psi
:> 225 psi H.P at ambient of 48 celsius
:> Thermostate probe is away from evaporator
:> thermostate accuracy is 98% (after testing)
:> Thermostate was tripping compressor at temprature of -15 degree celsius
:> expansion vallve model used in unit is danfoss TEX-5 (new installed)

Any other steps i've checked please tell me

[The Viking]

1. What refrigerant is used?

2. Is the system operating and not reaching set point or is the thermostat stopping the unit before the room reached the desired temperature?

3. What is the liquid line temperature as it comes out of the condensor? Before it enters the TEV (~6" before)?

4. What is the suction line temperature by the TEV's bulb?


.

[The Viking]

Sorry,
Also, what are the high and low side pressures when the above temperatures are taken?

[Sandro Baptista]

1. What refrigerant is used?

2. Is the system operating and not reaching set point or is the thermostat stopping the unit before the room reached the desired temperature?

3. What is the liquid line temperature as it comes out of the condensor? Before it enters the TEV (~6" before)?

4. What is the suction line temperature by the TEV's bulb?


.

I presume nawaz is using R22 since he's using a TEX DANFOSS valve.

"225 psi H.P at ambient of 48 celsius" » Something is wrong. Are you sure it is 48ºC. Is the condenser air cooled or evaporative type?

[The Viking]

I presume nawaz is using R22 since he's using a TEX DANFOSS valve.

OK,
But as he looking at a freezer where he want to maintain -18ºC R22 is an unlikely candidate, hence the TEV might be the wrong one... Or, it might been designed as a fridge and someone just lowered the set point.

There are a lot of strange data in the OP, therefore "back to basics":

1. What refrigerant is used?
2. Is the system operating and not reaching set point or is the thermostat stopping the unit before the room reached the desired temperature?
3. What is the liquid line temperature as it comes out of the condensor? Before it enters the TEV (~6" before)?
4. What is the suction line temperature by the TEV's bulb?
5. What are the high and low sides' running pressures?

Oh, not forgetting the all important;
6. Has this system managed to maintain -18ºC in the past?

:cool:

.

[D.D.KORANNE]

Check the refrigeration system for refrigerant leak...a minute leak could result i temperature shift .