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The system's rated cooling capacity in tons.
Typical residential split-system sizes range from 1.5 to 5 tons. This reference assumes standard line lengths (~25-50 ft) with minimal elevation change.
Typical suction and liquid line size
0.88 in (nominal suction line OD)
Nominal sizes: 7/8 in suction, 3/8 in liquid — order by that designation rather than by the decimal in the headline, which is rounded. This is a typical-case reference for standard line lengths (~25-50 ft) with minimal elevation change, consistent across common manufacturer data — it is not a substitute for the specific equipment manufacturer's line sizing chart, which governs for longer runs, larger elevation differences, or different refrigerants.
- Liquid line size
- 0.38 in (nominal liquid line OD)
They open the calculator with your figures already in it
Refrigerant Line Set Nominal Size Reference Calculator: 0.875 in (nominal suction line OD) — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Typical nominal suction and liquid line sizes for residential R-410A split-system air conditioners/heat pumps at standard line lengths (~25-50 ft, minimal elevation change), consistent across common manufacturer engineering/installation data (e.g. Carrier, Trane, Rheem residential split-system manuals). Longer line lengths, larger elevation differences, or different refrigerants require the specific equipment manufacturer's line sizing chart — this is a typical-case reference only, not a substitute for it.
Inputs used
- Cooling Capacity (Tons)
- 3 Tons
Intermediate steps
- Liquid line size
- 0.38 in (nominal liquid line OD)
Confidence note: Nominal sizes: 7/8 in suction, 3/8 in liquid — order by that designation rather than by the decimal in the headline, which is rounded. This is a typical-case reference for standard line lengths (~25-50 ft) with minimal elevation change, consistent across common manufacturer data — it is not a substitute for the specific equipment manufacturer's line sizing chart, which governs for longer runs, larger elevation differences, or different refrigerants.
What this calculation does not cover
- Says nothing about oil return, which is what actually governs a suction riser. Where the outdoor unit sits above the indoor coil, the vapor has to move fast enough up the vertical leg to carry compressor oil with it, and the fix is often a SMALLER riser than a capacity table gives, or a trap and a double riser on a modulating system. A generously sized riser on a lift starves the compressor of oil over months, not minutes.
- Gives a diameter, not a charge. Refrigerant to add beyond the factory pre-charge is set by the LIQUID line's diameter and total length — quoted per foot beyond a 15 or 25 ft (7.5 m) factory allowance — so two systems sharing this suction size can need very different amounts of R-410A in the drum, and guessing it undercharges the machine.
- Reads as one indoor coil on one line set. Multi-zone and branch-box systems size each branch from its own connected capacity and the trunk from the diversified total, not from the outdoor unit's nameplate tonnage, so pricing a multi-head job off this table over-sizes every branch run.
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This result is a specification — 0.88 in (nominal suction line OD) — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Typical nominal suction and liquid line sizes for residential R-410A split-system air conditioners/heat pumps at standard line lengths (~25-50 ft, minimal elevation change), consistent across common manufacturer engineering/installation data (e.g. Carrier, Trane, Rheem residential split-system manuals). Longer line lengths, larger elevation differences, or different refrigerants require the specific equipment manufacturer's line sizing chart — this is a typical-case reference only, not a substitute for it.
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