Hi guys

I used to working on more commercial systems but I’ve come across some minus 70 degree Celsius freezers on a site. Im trying to look into the operation of these condensers (Refra) one system is running on 449a and the other on 407a (I think but I’m not sure) anyway both of these systems are running their suction in a vacuum, which I’ve just never come across before, I’ve tried to do some research but can’t find anything. Is this just as simple as it sounds or is there more to these systems than meets the eye? If someone could point me in the right direction I’d appreciate it.

Cheers