What equivalent length should I use for elbows and fittings?

Q: What size line set do I need for a 3-ton AC?

For a 3-ton air-conditioning or heat-pump system at a normal length, the tool returns a 7/8 inch suction line and a 3/8 inch liquid line from common R-410A line-set tables. Sizes step up for lower-temperature refrigeration applications because lower vapor density needs a larger suction line to keep oil moving back to the compressor. Always verify against the equipment line-size chart before brazing.