TOSOT mini split line set sizes
Short answer: the right TOSOT mini split line set size depends on the series, not just the BTUs. A Cosmo 9k–12k uses 1/4" × 3/8", but the hyper-heat Aoraki 12k jumps to 1/4" × 1/2" — same capacity, bigger suction line. At 18k–24k the Cosmo runs 1/4" × 1/2" while the Aoraki 24k and legacy Muse 24k take 1/4" × 5/8", and even the 30k–36k Cosmo keeps a Gree-style 1/4" liquid line with a 5/8" suction. Sizes here come from Tosot's own manuals and compatibility chart; confirm yours before buying.
TOSOT is Gree's consumer brand — the units are Gree hardware under a friendlier name, and they carry Gree factory model numbers on the nameplate (a Cosmo 9k is a GWH09AWCXB). That heritage shows in the pipe sizing, so here's the whole current lineup in one place, pulled from Tosot's manuals and its line-set compatibility chart. Prefer to size by run length too? Use the size calculator.
TOSOT line set size by capacity
Tosot's US single-zone lineup today is two series — Cosmo (the mainline R-32 wall-mount, 9k–36k) and Aoraki (the R-32 hyper-heat line, 12k–24k) — plus the legacy Muse still sold through some retailers. If you've seen "Bora" or "Sena" on a sizing chart, ignore it: those series don't exist in the US lineup. All connections are flared.
| TOSOT system size | Line set (liquid × suction) |
|---|---|
| 9,000 BTU | 1/4" × 3/8" (Cosmo, Muse) |
| 12,000 BTU | 1/4" × 3/8" (Cosmo, Muse) or 1/4" × 1/2" (Aoraki) |
| 18,000 BTU | 1/4" × 1/2" (Cosmo, Aoraki, Muse) |
| 24,000 BTU | 1/4" × 1/2" (Cosmo) or 1/4" × 5/8" (Aoraki, Muse) |
| 30,000–36,000 BTU | 1/4" × 5/8" (Cosmo) |
On multi-zone Cosmo systems, each indoor head connects with its own pair: 9k and 12k heads use 1/4" × 3/8", and 18k and 24k heads use 1/4" × 1/2".
Found your size? Get the matching line set
We stock the two most common Tosot sizes: 1/4" × 3/8" for the Cosmo and Muse 9k–12k (and 9k–12k multi-zone heads), and 1/4" × 1/2" for the Cosmo 18k–24k, Aoraki 12k–18k, Muse 18k, and 18k–24k multi-zone heads — in 16 ft and 25 ft, open for preorder. Since Tosot already includes a 16 ft set in the box, most buyers here need the longer run — grab the 25 ft line set.
Two traps: the 12k split and the 24k split
Tosot sizing has two places where the BTU number alone will steer you wrong. First, at 12,000 BTU the series disagree: a Cosmo 12k uses 1/4" × 3/8", but the hyper-heat Aoraki 12k uses 1/4" × 1/2" — same capacity, different series, different size. Second, at 24,000 BTU they split again: the Cosmo 24k takes 1/4" × 1/2" while the legacy Muse 24k (and the Aoraki 24k) take 1/4" × 5/8". And like parent brand Gree, Tosot never steps up to a 3/8" liquid line — even the 36k Cosmo keeps 1/4" liquid with a 5/8" suction. If a generic chart says a 3-ton needs 3/8" × 5/8", it isn't talking about a Tosot.
Flared, not quick-connect — with a 16 ft set in the box
Tosot units use standard field-flared connections, not pre-charged quick-connect. The manual's torque table is specific: 12–14 ft-lb on the 1/4" nut, 23–29 on 3/8", 34–40 on 1/2", and 45–47 on 5/8". A 16 ft line set is included with every single-zone system, and Tosot sells accessory sets in 16, 25, and 50 ft if you need a different length. The included set is real flared copper: you still pull a vacuum before opening the valves, which needs a vacuum pump and typically EPA 608 certification. If your run is longer than 16 ft, buy the right length outright rather than coupling two sets — see our standard line sets, or pre-charged line sets if you want the true no-vacuum route on a compatible system.
TOSOT line set length limits
Every Tosot single-zone wants at least 10 ft of line, and the factory charge covers the first 25 ft on all of them. The ceilings vary by series and capacity — with one wrinkle worth knowing.
| Series and capacity | Min line length | Max line length | Pre-charged for |
|---|---|---|---|
| Cosmo 9,000–12,000 BTU | 10 ft | 65 ft | 25 ft |
| Cosmo 18,000–24,000 BTU | 10 ft | 82 ft (manual) | 25 ft |
| Cosmo 30,000–36,000 BTU | 10 ft | 131 ft | 25 ft |
| Aoraki 12,000 BTU | 10 ft | 65 ft | 25 ft |
| Aoraki 18,000–24,000 BTU | 10 ft | 131 ft | 25 ft |
The wrinkle: for the Cosmo 18k–24k, the printed manual says 82 ft while Tosot's online line-set calculator allows 131 ft. When a manufacturer's own sources disagree, go with the manual — it's the document your warranty rides on. Beyond 25 ft of line, add refrigerant per extra foot: 0.2 oz/ft on the Cosmo 9k–24k and Aoraki 12k–18k, and 0.4 oz/ft on the Cosmo 30k–36k and Aoraki 24k — a gauges-and-scale job for an HVAC pro, not a guess. One gap to note: Tosot doesn't publish a maximum vertical separation for these units, so if your outdoor unit sits far above or below the head, ask Tosot support for your model's limit rather than assuming one.
Refrigerant: R-32 now, R-410A on the legacy Muse
Tosot's current single-zone lineup — Cosmo and Aoraki — runs R-32. The older Muse is still sold through some retailers, and those listings spec it as R-410A (Tosot's own current pages don't cover it, so treat that as per-retailer). The copper line set is the same either way; your tools, gauges, and any added charge are not. Check the nameplate before you charge anything.
How to find your TOSOT model's line set size
- Read the Tosot model number. They follow a pattern like TST-SU-C12K23: SU means single zone, the next letter names the series (C for Cosmo, A for Aoraki), then the capacity, and the final digits give the voltage (11 = 115V, 23 = 230V).
- Or read the Gree number on the nameplate. Because Tosot units are Gree-built, the nameplate carries a Gree factory model like GWH09AWCXB — searching that number pulls up the same specs.
- Check the manual's piping table. It lists the exact liquid and suction diameters, the flare torque values, and the length limits for your unit — the final word before you buy copper.
Common questions
What size line set does a TOSOT 12,000 BTU use?
It depends on the series — this is the classic Tosot trap. A Cosmo 12k (and a legacy Muse 12k) uses 1/4" × 3/8", but the hyper-heat Aoraki 12k uses 1/4" × 1/2". Same capacity, different series, different copper — identify your series before ordering.
What size line set does a TOSOT 24,000 BTU use?
A Cosmo 24k uses 1/4" × 1/2", while the Aoraki 24k and the legacy Muse 24k use 1/4" × 5/8". A Cosmo 24k head on a multi-zone system also uses 1/4" × 1/2". Check which series you have before buying copper.
Is TOSOT the same as Gree?
TOSOT is Gree's consumer brand — the units are built by Gree and carry Gree factory model numbers (a Cosmo 9k, for example, is a GWH09AWCXB). That's why Tosot sizing habits mirror Gree's, including keeping a 1/4" liquid line even at 36,000 BTU.
Do TOSOT mini-splits use quick-connect or flared line sets?
Tosot uses standard field-flared connections, not pre-charged quick-connect. A 16 ft line set is included with single-zone systems, and Tosot sells accessory sets in 16, 25, and 50 ft. You still flare the copper, torque the nuts to the manual's table, and pull a vacuum before opening the service valves.
What refrigerant do TOSOT mini-splits use?
The current single-zone lineup — Cosmo and the hyper-heat Aoraki — runs R-32. The legacy Muse series is listed as R-410A by retailers still selling it. The copper is the same either way, but your gauges, tools, and any added charge must match the unit's refrigerant.
What is the maximum line set length for a TOSOT mini-split?
By series: Cosmo 9k–12k and Aoraki 12k allow 65 ft; Cosmo 18k–24k allow 82 ft per the printed manual (Tosot's online calculator shows 131 ft — go with the manual); Cosmo 30k–36k and Aoraki 18k–24k allow 131 ft. Minimum is 10 ft on all single-zone units, and Tosot doesn't publish a maximum vertical separation.
Line set sizes for other brands: Gree · Della · Senville · Pioneer · MRCOOL
This page provides general guidance on TOSOT mini-split line set sizing based on Tosot's published installation manuals, product pages, and line-set compatibility chart (Cosmo, Aoraki, and legacy Muse series; Muse refrigerant per retailer listings). Exact diameters, length limits, and refrigerant (R-32 current, R-410A on legacy series) vary by model — always verify against your unit's official installation manual before purchasing or installing.