Hello July looking for in my notes I found that 1Hp is needed for every 10M3 of environment and in your case it gives me 20.12 M3 so that to be comfortable you need a 2.5Hp equipment and better if it was 3Hp. Nowadays the equipment is already sized, both its condenser and evaporator for so many Hp that you are going to use or evaporators with forcing or without forcing, then it depends on which gas you want to use and whether it is with a valve or a capillary or if it is semi-hermetic or with armored ball. which can you advise the seller of the equipment. He believes that such equipment would be good to put even a low and high pressure switch and in his case the low pressure alone (for protection) and again as the colleague says take into account the isolation of the camera. And in the case that you do not forget to isolate the pipe that is outside the chamber well greetings I hope it serves you