Della line set sizes
Short answer: Every current Della wall-mount at 9,000–12,000 BTU uses a 1/4" × 3/8" line set. At 18,000 BTU the series matters: the Vario stays at 1/4" × 3/8" while Optima and Optima Pro step to 1/4" × 1/2". Larger units keep Della's signature 1/4" liquid line — 24k runs 1/4" × 1/2" (Vario) or 1/4" × 5/8" (Optima), and the 36k Vario uses 1/4" × 5/8". Sizes here come from Della's own installation manuals; confirm yours before buying.
Della sells more mini-splits through Amazon and Walmart than almost anyone, but its spec pages bury the line set size under "connecting pipe" — so here's the whole current lineup in one place, pulled from the Vario, Optima, and Optima Pro manuals. Prefer to size by run length too? Use the size calculator.
Della line set size by capacity
Della's current single-zone wall-mounts are three series — Vario (the value line), Optima (Ultra Heat, including the CloudAir variants), and Optima Pro (Ultra Hyper Heat). All three agree on the small sizes and drift apart from 18k up.
| Della system size | Line set (liquid × suction) |
|---|---|
| 9,000 BTU | 1/4" × 3/8" |
| 12,000 BTU | 1/4" × 3/8" |
| 18,000 BTU | 1/4" × 3/8" (Vario) or 1/4" × 1/2" (Optima, Optima Pro) |
| 23,000–24,000 BTU | 1/4" × 1/2" (Vario) or 1/4" × 5/8" (Optima, Optima Pro) |
| 36,000 BTU | 1/4" × 5/8" (Vario) |
Found your size? Get the matching line set
We stock the two most common Della sizes: 1/4" × 3/8" for every 9k–12k and the Vario 18k, and 1/4" × 1/2" for the Optima-series 18k and Vario 24k — in 16 ft and 25 ft, open for preorder.
The 18k split — and Della's 1/4" liquid line
Two things make Della sizing easy to get wrong. First, the 18,000 BTU units don't agree with each other: a Vario 18k runs an unusually small 1/4" × 3/8", while the Optima and Optima Pro 18k take 1/4" × 1/2" — so identify your series before ordering copper. Second, like Gree and unlike most brands, Della never steps up to a 3/8" liquid line — even the 36k Vario keeps 1/4" liquid with a 5/8" suction. If a sizing chart tells you a 3-ton unit needs 3/8" × 5/8", it isn't talking about a Della.
Flared, not quick-connect — with the line set in the box
Della units use standard field-flared connections, not pre-charged quick-connect — the manuals walk through cutting, flaring, and torquing the nuts (18–20 N·m on the 1/4" line). A 16.4 ft line set is included with current units, and many listings let you swap it for a 10, 25, 33, or 50 ft kit at purchase. That 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 the included set, 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.
Della line set length limits
Della's limits scale cleanly with capacity, and the factory charge covers the same first 25 ft on every current model.
| Capacity | Max line length | Max vertical separation | Pre-charged for |
|---|---|---|---|
| 9,000–12,000 BTU | 49 ft (15 m) | 33 ft (10 m) | 25 ft |
| 18,000–24,000 BTU | 65 ft (20 m) | 49 ft (15 m) | 25 ft |
| 36,000 BTU | 98 ft (30 m) | 65 ft (20 m) | 25 ft |
Beyond 25 ft of line, add about 0.11 oz of refrigerant per extra foot — that's a gauges-and-scale job for an HVAC pro, not a guess. Note the ceilings are lower than most brands (a Senville 12k allows ~82 ft to Della's 49 ft), so check the max before planning a long run to a far corner of the house.
Refrigerant: R-454B now, R-32 on the older series
Della's current Vario, Optima, and Optima Pro all ship with R-454B, in line with the industry's move away from R-410A. But Della's older series are still widely sold online — Serena and Motto units use R-32 — so a Della bought new today isn't guaranteed to match the refrigerant of one bought last year. 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 Della model's line set size
- Find the series in the model number. Della model numbers read like 048-TL-12K2VB-23S — the letters after "048-" name the series: TL is Vario, TP/TPX is Optima and CloudAir, TPH/TPHX is Optima Pro, and legacy MS-M/MS-JA are Serena and Motto.
- Check the manual's connecting-pipe table. It lists the exact liquid and suction diameters, the maximum line length, and the refrigerant for your unit — the final word before you buy copper.
Common questions
What size line set does a Della 12,000 BTU use?
Every current Della 12,000 BTU wall-mount — Vario, Optima, and Optima Pro — uses a 1/4" liquid line with a 3/8" suction line, and the 9,000 BTU models use the same pair. Confirm against your model's installation manual.
What size line set does a Della 18,000 BTU use?
It depends on the series. A Della Vario 18k uses 1/4" × 3/8" — unusually small for an 18k — while the Optima and Optima Pro 18k step up to 1/4" × 1/2". Check which series you have before buying copper.
Do Della mini-splits use quick-connect or flared line sets?
Della uses standard field-flared line sets, not pre-charged quick-connect. The outdoor unit ships pre-charged for up to 25 ft of line and a 16.4 ft line set is included in the box, but you still flare the copper and pull a vacuum before opening the service valves — which needs a vacuum pump and typically EPA 608 certification.
What refrigerant do Della mini-splits use?
Della's current lineup — Vario, Optima, and Optima Pro — ships with R-454B, in line with the industry transition away from R-410A. Older Della series still sold through some retailers, such as Serena and Motto, use R-32. Match your tools, gauges, and any added charge to your unit's refrigerant.
What length line set comes with a Della mini-split?
Della includes a 16.4 ft (5 m) line set with its current units, and many listings offer 10, 25, 33, or 50 ft kits instead. The factory charge covers up to 25 ft of line; beyond that, add about 0.11 oz of refrigerant per extra foot — a job for an HVAC pro.
What is the maximum line set length for a Della mini-split?
It scales with capacity: about 49 ft of line and 33 ft of vertical separation on 9,000–12,000 BTU units, 65 ft and 49 ft on 18,000–24,000 BTU units, and 98 ft and 65 ft on the 36,000 BTU Vario. Confirm your unit's maximum in its manual.
Line set sizes for other brands: Senville · MRCOOL · Pioneer · Cooper & Hunter · Gree
This page provides general guidance on Della mini-split line set sizing based on Della's published installation manuals and specification pages (Vario TL, Optima TP/TPX, and Optima Pro TPH/TPHX series). Exact diameters, length limits, and refrigerant (R-454B or R-32 on legacy series) vary by model — always verify against your unit's official installation manual before purchasing or installing.