Method of forming refrigerant systems

A method for forming an improved, centralized refrigeration system comprising:

• (a) providing an existing refrigeration circuit comprising:
• (i) an existing refrigerant having a GWP of greater than 1200;
• (ii) a plurality of evaporators located in or near a refrigerated space containing products accessible to consumers and (ii) at least one compressor or rack of compressors and at least one condenser located remotely from areas accessible to said consumers, wherein said existing refrigerant from said condenser is fluidly connected to said evaporators via conduit(s) and wherein existing refrigerant vapor from said evaporators is returned via conduits to a suction side of said compressor or compressor rack;
• (b) disconnecting the fluid connection between said existing refrigerant liquid from said condenser and at least one of said evaporators;
• (c) disconnecting the fluid connection between said existing refrigerant vapor from said at least one of said evaporators in step (b) and said suction of said compressor or compressor rack;
• (d) establishing a new first refrigeration circuit comprising said compressor or compressor rack and said condenser, wherein said existing refrigerant remains in said first refrigeration circuit or wherein said existing refrigerant is at least partially removed and replaced;
• (e) establishing a new second refrigeration circuit comprising said at least one of said evaporators that has been disconnected in steps (b) and (c) by steps comprising:
• (i) removing said existing refrigerant from said evaporators and at least a portion of said conduits which have been disconnected in steps (b) and (c);
• (ii) replacing said removed existing refrigerant with a second refrigerant comprising:
• (1) at least about 50% by weight of R1234ze(E);
• (2) greater than 0% to about 10% of a second component, wherein said second component is selected from the group consisting of HFC-134a, HFC-134, HFC-227ea, HFC-125, and combinations of two or more of these;
• and (3) from about 10% to about 20% by weight of a third component, wherein said third component is selected from the group consisting of HFO-1336mzz(E), HFO-1224 yd(Z), and combinations of these, wherein said second refrigerant:
• (i) has an Occupational Exposure Limit (OEL) greater than 400;
• (ii) is classified as class A1 by ASHRAE Standard 34;
• and (iii) has a GWP of about 150 or less;
• and
• (f) thermally interconnecting said new first refrigeration circuit and said new second refrigeration circuit with an inter-circuit heat exchanger in which at least a portion of said refrigerant in said first circuit is vaporized by absorbing heat from said second circuit refrigerant vapor and wherein at least a portion of said second refrigerant is condensed by transferring heat to said first circuit refrigerant.