Mini-Split Line Set Calculator (Small-Capacity System Sizing)

Every figure here traces to Goodman/Amana's own published TP-107 "Long Line Set Application, R-410A" guideline — this is that manufacturer's specific published guidance, not a universal industry constant, since other manufacturers publish meaningfully different thresholds for their own equipment (see Limitations). Total Equivalent Length is the straight (linear) length plus a per-elbow equivalent-length addition for long-radius 90° and 45° elbows only (short-radius elbows add slightly more per elbow than this calculator models). Maximum Equivalent/Linear Length depends on your selected compressor type — 250/200 ft for single-stage scroll or reciprocating compressors, 150/150 ft for single-stage rotary or two-stage. For two-stage HEAT PUMPS specifically, Table 5-3's own footnotes additionally prohibit 7/8in suction at 24,000 BTU entirely, 7/8in suction beyond 80 ft equivalent length at 36,000 BTU, and 1-1/8in suction beyond 80 ft equivalent length at 48,000/60,000 BTU — flagged separately above when applicable. Capacity Multiplier is looked up from a table of capacity x suction diameter x equivalent length, linearly interpolated between the nearest documented length columns (25-250 ft) and clamped at the table's own boundaries rather than extrapolated beyond them. Two cells in that table (30,000 BTU/3-4in/175ft and 60,000 BTU/7-8in/200ft) printed values that broke the otherwise-smooth pattern of their row; this calculator adjusts them to match the surrounding values as an INFERRED correction, not an official manufacturer erratum — if your exact scenario lands at one of those two cells, cross-check directly against the published PDF. Additional Refrigerant Charge uses the ACTUAL straight length (not equivalent length) beyond the 15 ft factory-charge baseline, at a rate specific to the 3/8in liquid line paired with your selected suction diameter — this figure is R-410A only; R-32 and R-454B systems use different refrigerant densities and are not modeled, since no consistent charge-rate figure was found for them. No published rate exists for 1/2in suction at all — that combination falls back to a liquid-line-only rate that likely understates the true charge (see the Refrigerant Charge card above when this applies). "Same Level" only applies up to 10 ft of separation between the units — beyond that, TP-107 says to categorize the installation as Above or Below instead. The elevation rules are genuinely asymmetric by direction and equipment type: an outdoor unit installed BELOW the indoor unit has a hard maximum of 80 ft (any equipment type) plus an always-required inverted suction trap, a required liquid line solenoid (any equipment type, unless a non-bleed TXV is used), and, for air conditioners over 79ft, an accumulator; an outdoor unit ABOVE the indoor unit has no stated hard maximum for a single-stage air conditioner, an 80 ft hard maximum for a single-stage heat pump, and a 25 ft hard maximum for two-stage equipment of either type — separately, an oil trap is required above 80 ft regardless of equipment type, and heat pumps (any position) require the same liquid line solenoid. This is a planning estimate — always verify against your specific installed or selected unit's own installation manual before purchasing materials or beginning installation.