Fridge and Freezer Unit

[ferret82]

HI There,

Just woud like some clarification whether or not i am taking the measurments right to calculate SC and SH on this system in the pitcures.

Fridges picture - You can see both the units. There is 2 units for the Freezer and 2 for Fridges. This set up is in a shipping container the there is 3 comaprtment Freezer, Fridge, Drystore(thiis is cooled by an A/C

In The photos i have put red marker on them to show where i am taking these measurments from hopefully they are correct.

These units are designed to operate at 43degC but today was 50degC+ so they are just continually running as they cant pull the cabnets down to temp. I have notice that there is not much air flow behind the units also. Are these two factors what woudl cause high head pressures? The fridges were up about 370psig and freezers were about 300psig.


Any info woudl be great.

[ferret82]

Something i should have said is that i am taking the temperatures on the pipework about 6inchs from the condensor outlet on both units and the gauge pressures for High and Low and also the temp at the shrodder valve seen in the photo of the TX Valve.

This is how i am working out SC SH.

[Brian_UK]

Just looking at the first picture with the condensing units explains one reason why you are suffering.

How is any cool air supposed to get to the front of the condenser coils?

At the moment it looks as though the air is recirculated within the boxes.

[lowcool]

wouldnt be to concerned about head pressures,correcting the airflow will ease some of this off.however i would be dropping the 404 and using 507 as this will aid in correct superheat adjustment.good to see the client has realised the extra cost of these units are worth it in extremes.if it was heatcraft say you would probably be winding the hp safety off the scale.

been a lovely pommy heat wave hasnt it.
have a beer and relax
cheers

[ferret82]

Just wondering could you please explain why you change the refrigerant from R404a to 507. WOuld I need to change anything else on the system or can i evacuate the system and put it in?

[lowcool]

404 is a combo of 134 & 507 and becomes unstable in high temp conditions.507 is the native gas 134 was added to get around a copyright patent etc.