408a in the heat

[duckman373]

This is my first summer in Phoenix. I have run into some high head presure on w/i freezers using R408a. Have any of you out there working in 110 degree temps running into the same probs? How do you adjust for it?

[icemeister]

All blends run at higher condensing pressures than the old favorites.....R12/R22/R502. Try to think more in terms of reasonable condensing temperatures for the ambients you have. Have your P/T chart handy, look up the SCT and then decide if your head is "too high".

I'm not going to switch to "All-Shot" just because it's pressure is 20# lower at the same saturated condensing temperature as R408A or HP80 (the one I use).

[Yuma]

Originally posted by duckman373
This is my first summer in Phoenix. I have run into some high head presure on w/i freezers using R408a. Have any of you out there working in 110 degree temps running into the same probs? How do you adjust for it?

Here in Yuma we have a number of freezers and ice cream machines that we have R-408 in. Any 502 system that we have to convert from 502. (We have not switched them to 404 because of the oil and TXV changes needed).
We just do not fill them as full. 80% of charge only. On boxes with sight glasses leave a few bubbles (more in the summer). Also set the pressure controls to a high limit of 415-425 psig.
And yes we are hotter then Phoenix and dryer.

Yuma,