R134A Running Pressures

[borodave1973]

Hi

Apologies if this is in the wrong thread!

We have been asked to look at a walk in freezer operating on on R134A i have never been to look at a freezer running on R134A what sort of running pressures should i be looking for to get the freezer down to -18oC? Currently the freezer is only achieving around -8oC

Am i right in thinking the suction should be around 1psig?

Thanks in advance for any help

[Tradewinds]

Hi Borodave,

Forget about pressures and use temperature. You should be evaporating at about -25'C for a freezer. So look for -25'c on your blue gauge on the 134a scale.

To keep it simple, use these rules of thumb:
Freezer = SST of -25'c
Coolroom = SST of -5'c
AC = SST of +5'c

Using these 3 temperatures you will be able to work with any refrigerant.