Daikin line set sizes
Short answer: Daikin single-zone wall-mounts use a 1/4" liquid line on every size — even a 24,000 or 36,000 BTU unit — with the gas line stepping from 3/8" (9,000–12,000 BTU) to 1/2" (15,000–18,000 BTU) to 5/8" (24,000 BTU and up). That constant 1/4" liquid line is what sets Daikin apart from most brands. Confirm your model in its manual.
The right line set diameter for your Daikin mini-split by capacity — plus the one thing that sets Daikin apart: most current units run R-32 refrigerant, not R-454B. Prefer to size by run length too? Use the size calculator.
Daikin line set size by capacity
Line set diameter is set by your system's capacity. Match your Daikin unit's BTU rating to the typical liquid-and-suction pair below. Sizes can shift slightly by series, so treat this as a starting point and confirm against your manual.
| Daikin system size | Typical line set (liquid × suction) |
|---|---|
| 9,000 BTU | 1/4" × 3/8" |
| 12,000 BTU | 1/4" × 3/8" |
| 15,000 BTU | 1/4" × 1/2" |
| 18,000 BTU | 1/4" × 1/2" |
| 24,000 BTU | 1/4" × 5/8" |
| 36,000 BTU | 1/4" × 5/8" |
Found your size? Get the matching line set
We stock pre-flared, insulated line sets in the sizes Daikin uses: 1/4" × 3/8" for 9k–12k units and 1/4" × 1/2" for 15k–18k. 16 ft and 25 ft, open for preorder.
These are the most common single-zone wall-mount pairings. Ducted and SkyAir models at the same capacity can step up a size, and the exact liquid and gas diameters for your unit are printed in its installation manual. Always confirm there before buying.
Daikin line set size by model
Daikin owners usually know their indoor model — FTXB12, FTXR18, FTXV24, and so on. The pattern is consistent across every Daikin wall-mount series: a 1/4" liquid line at every capacity, with only the gas line stepping up as the unit gets larger.
| Series (example models) | 9k–12k | 15k–18k | 24k+ | Refrigerant |
|---|---|---|---|---|
| FTXB — Aurora (FTXB09/12/18/24XVJU) | 1/4" × 3/8" | 1/4" × 1/2" | 1/4" × 5/8" | R-410A |
| FTX — 19-Series (FTX09/12/15/18NMVJU) | 1/4" × 3/8" | 1/4" × 1/2" | — | R-410A |
| FTXR — Emura (FTXR09/12/18TVJU) | 1/4" × 3/8" | 1/4" × 1/2" | — | R-410A |
| FTXG — Quaternity (FTXG09/12/15HVJU) | 1/4" × 3/8" | 1/4" × 1/2" | — | R-410A |
| FTXV — Aurora R-32 (FTXV09/12/18/24AVJU9) | 1/4" × 3/8" | 1/4" × 1/2" | 1/4" × 5/8" | R-32 |
| FTX30/36 — Polara (FTX30/36WVJU9) | — | — | 1/4" × 5/8" | R-410A |
The takeaway: Daikin keeps a 1/4" liquid line on every single-zone wall-mount, even a 24k or 36k, where most brands move to a 3/8" liquid line. Only the gas line grows — 3/8" up to 12k, 1/2" at 15k–18k, and 5/8" at 24k and above. The newer FTXV Aurora runs R-32 (Daikin's choice instead of R-454B) but uses the same diameters as its R-410A equivalent. On a multi-zone Daikin (2MXS, 3MXS, or the R-32 MXM), each head gets its own line set sized to that head, with reducers at the larger outdoor-unit ports.
Daikin runs R-32 — match your line set, tools, and charge
Here is the Daikin difference: its current ductless lineup, including the Aurora series, uses R-32 refrigerant, while most other brands moved to R-454B. Older Daikin units use R-410A. The copper line set itself is the same regardless of refrigerant, but your vacuum pump, gauges, and any field charge must match your unit's refrigerant — confirm which one your model uses before you buy tools or add refrigerant.
Field-flared, not quick-connect
Unlike a pre-charged DIY brand such as MRCOOL, Daikin mini-splits use standard field-flared line sets. You flare the copper ends and pull a vacuum to remove air and moisture before releasing the refrigerant — work that typically needs a vacuum pump and EPA 608 certification. Shop standard line sets for a Daikin install, or see pre-charged line sets if you want the no-vacuum route on a compatible system.
Daikin line set length limits
Diameter is only half the spec. Your Daikin system also limits how long the line set can run and how far the indoor and outdoor units can sit apart in height. Plan your run to the figures below, then confirm the exact limits for your model in its installation manual.
| Minimum line length | Maximum line length | Max vertical separation | Pre-charged for |
|---|---|---|---|
| ~10 ft (recommended) | 66–98 ft by capacity | 49–66 ft by capacity | 33–49 ft by refrigerant |
Daikin's R-410A and R-32 single-zone systems both allow about 66 ft of line on 9,000–12,000 BTU units, with up to 49 ft of vertical separation, and about 98 ft on 18,000–36,000 BTU units, with up to 66 ft of lift. The factory charge covers the first 33 ft or so on R-410A models and about 49 ft on the R-32 Aurora series; beyond that an HVAC pro adds roughly 0.21–0.22 oz per extra foot. Daikin lists about 10 ft as a recommended minimum to limit noise and vibration, not a hard cutoff.
Stocked lengths and multi-zone runs
Because Daikin uses standard line sets, you size to your run rather than to fixed pre-charged lengths — common stocked lengths are 15, 25, 35, and 50 ft.
Multi-zone systems use a separate line set per indoor unit. On a Daikin multi-zone (one outdoor unit, several heads), each indoor unit gets its own correctly sized line set running back to the condenser — size each run to that head's capacity, not the whole system.
How to find your Daikin model's line set size
- Identify the model and series. Note the indoor unit model number and capacity — line size depends on the specific unit, and ducted models can differ from wall-mounted at the same BTU.
- Check the installation manual. It lists the exact liquid and suction diameters, the maximum line length, the refrigerant (R-32 or R-410A), and any flare-torque specs for your model — the final word.
Common questions
What size line set does a Daikin 12,000 BTU use?
A Daikin 12,000 BTU single-zone wall-mount uses a 1/4" liquid line with a 3/8" gas line, the same as the 9,000 BTU. Ducted units at the same capacity can differ. Confirm the exact sizes in your model's installation manual.
What refrigerant do Daikin mini-splits use?
Daikin's current ductless lineup, such as the Aurora series, uses R-32 refrigerant — unlike most other brands that moved to R-454B. Older Daikin units use R-410A. The copper line set is the same either way, but your tools, gauges, and any added charge must match your unit's refrigerant.
Do Daikin mini-splits use quick-connect or flared line sets?
Daikin uses standard field-flared line sets, not pre-charged quick-connect. You flare the copper ends and pull a vacuum before releasing refrigerant, so a Daikin install needs a vacuum pump and typically EPA 608 certification.
What size line set does a Daikin 24,000 BTU use?
A Daikin 24,000 BTU single-zone wall-mount uses a 1/4" liquid line with a 5/8" gas line — Daikin keeps the 1/4" liquid line even at this size, where most brands move to 3/8". The 30,000 and 36,000 BTU wall-mounts use the same 1/4" × 5/8". Larger ducted units can step up. Verify against your unit's manual.
What is the minimum line set length for a Daikin mini-split?
Daikin lists about 10 feet (3 m) as a recommended minimum line set length to limit compressor noise and vibration, rather than a hard cutoff. Keep runs at or above that and follow your model's installation manual.
What is the maximum line set length for a Daikin mini-split?
Daikin single-zone systems, in both R-410A and R-32 Aurora form, allow about 66 ft of line on 9,000–12,000 BTU units and about 98 ft on 18,000–36,000 BTU units, with 49–66 ft of vertical separation. The factory charge covers roughly the first 33–49 ft; beyond that an HVAC pro adds refrigerant. Confirm your unit's maximum in its manual.
Can I reuse my existing line set with a Daikin mini-split?
Often yes — if the diameters match your new Daikin unit, the run length is within its limits, and the copper is clean and leak-free. Re-flare the ends, pressure-test, and pull a fresh vacuum before charging. Take extra care when switching refrigerants: a line set that carried R-410A should be flushed and verified clean before reuse on an R-32 Daikin. Always match a correctly sized line set and confirm against your unit's installation manual.
Line set sizes for other brands: Mitsubishi · LG · Fujitsu · MRCOOL · Pioneer
This page provides general guidance on Daikin mini-split line set sizing based on published Daikin specifications. Exact line diameters vary by series and model, and lengths, maximum line length, and refrigerant (R-32 or R-410A) differ by unit — always verify against your unit's official installation manual before purchasing or installing.