Senville line set sizes
Short answer: Senville 9,000–12,000 BTU units use a 1/4" × 3/8" line set, 18,000 BTU uses 1/4" × 1/2", and 24,000–36,000 BTU units use 3/8" × 5/8". Senville uses standard field-flared line sets — not pre-charged quick-connect — so plan on flaring the copper and pulling a vacuum. Always confirm against your model's installation manual.
The right line set diameter for your Senville LETO or AURA mini-split by capacity — plus the honest truth about the "DIY-friendly" label: a Senville is still a flared, vacuum-pulled install. Prefer to size by run length too? Use the size calculator.
Senville line set size by capacity
Line set diameter is set by your system's capacity. Senville follows the standard mini-split pairings, so match your unit's BTU rating to the liquid-and-gas pair below — these are Senville's own published flare sizes.
| Senville system size | Line set (liquid × gas) |
|---|---|
| 9,000 BTU | 1/4" × 3/8" |
| 12,000 BTU | 1/4" × 3/8" |
| 18,000 BTU | 1/4" × 1/2" |
| 24,000 BTU | 3/8" × 5/8" |
| 36,000 BTU | 3/8" × 5/8" |
Found your size? Get the matching line set
We stock all three Senville sizes: 1/4" × 3/8" for 9,000–12,000 BTU units, 1/4" × 1/2" for 18,000 BTU, and 3/8" × 5/8" for 24,000–36,000 BTU — in 16 ft and 25 ft, open for preorder.
Senville offers line sets in 16, 25, and 50 ft, and most systems include a 16 ft line set in the box. If your run is longer than the included set, buy the right length in the matching diameters above rather than coupling two sets together. Always confirm the sizes against your unit's manual.
"DIY-friendly" still means flaring and a vacuum
Senville is one of the most popular DIY mini-split brands, but that does not make it quick-connect. A Senville uses standard field-flared line sets: the outdoor unit ships pre-charged and a 16 ft line set is usually included, but you still flare the copper ends and pull a vacuum to remove air and moisture before opening the service valves. Plan on a vacuum pump and typically EPA 608 certification. If you want a true no-vacuum, no-flare install, that's a pre-charged quick-connect brand such as MRCOOL DIY — see pre-charged line sets.
Senville line set length limits
Diameter is only half the spec. Your Senville 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 (3 m) | 82–164 ft by capacity | 33–82 ft by capacity | 25 ft |
Senville's maximums climb with capacity. A 9,000–12,000 BTU unit allows about 82 ft of line with up to 33 ft of vertical separation, an 18,000 BTU about 98 ft with up to 66 ft of lift, and 24,000–36,000 BTU units up to 164 ft with up to 82 ft of lift. The factory charge covers about the first 25 ft; beyond that an HVAC pro adds refrigerant, roughly 0.16–0.32 oz per foot depending on the liquid line size. Senville lists a minimum run of about 10 ft to limit noise and vibration.
Stocked lengths and refrigerant
Because Senville uses standard line sets, you size to your run — common stocked lengths are 16, 25, 35, and 50 ft.
Match the refrigerant. Older Senville units use R-410A; newer LETO and AURA systems ship with R-454B as the industry replaces R-410A after January 1, 2026. The copper line set is the same either way, but your tools, gauges, and any added charge must match your system's refrigerant — check the data plate before you buy.
How to find your Senville model's line set size
- Identify the model and capacity. Note the model number (SENL-, SENA-, etc.) and BTU — Senville sizing follows the capacity, but always verify the exact figures.
- Check the installation manual. It lists the exact liquid and gas diameters, the maximum line length, the included line set length, and the refrigerant for your model — the final word.
Common questions
What size line set does a Senville 12,000 BTU use?
A Senville 12,000 BTU mini-split, such as the LETO SENL-12CD, uses a 1/4" liquid line with a 3/8" gas line. The 9,000 BTU models use the same 1/4" × 3/8" pair. Confirm against your model's installation manual.
Is a Senville a DIY install? Does it use quick-connect line sets?
Senville is popular with DIYers, but it uses standard field-flared line sets — not pre-charged quick-connect like a MRCOOL DIY. The outdoor unit ships pre-charged and a 16 ft line set is usually included, but you still flare the copper and pull a vacuum before opening the valves, which needs a vacuum pump and typically EPA 608 certification.
What size line set does a Senville 24,000 BTU use?
A Senville 24,000 BTU mini-split uses a 3/8" liquid line with a 5/8" gas line, and 36,000 BTU units use the same 3/8" × 5/8" pair. The 18,000 BTU sits between, at 1/4" × 1/2". Verify against your unit's manual.
What refrigerant do Senville mini-splits use?
Older Senville units use R-410A. Newer LETO and AURA systems ship with R-454B as the industry phases out R-410A after January 1, 2026. The copper line set is the same either way, but your tools and any added charge must match your unit's refrigerant.
What is the minimum line set length for a Senville mini-split?
Senville specifies a minimum line set length of about 10 feet (3 m) to limit noise and vibration. Keep your run at or above that and confirm the figure in your model's manual.
What is the maximum line set length for a Senville mini-split?
It depends on capacity. Senville's 9,000–12,000 BTU units allow about 82 ft of line, an 18,000 BTU about 98 ft, and 24,000–36,000 BTU units up to 164 ft, with 33–82 ft of vertical separation. The factory charge covers about the first 25 ft; beyond that an HVAC pro adds refrigerant. Confirm your unit's maximum in its manual.
Line set sizes for other brands: Mitsubishi · Daikin · LG · Fujitsu · MRCOOL · Della
This page provides general guidance on Senville mini-split line set sizing based on published Senville specifications. Exact line diameters, included line set length, maximum line length, and refrigerant (R-410A or R-454B) vary by model — always verify against your unit's official installation manual before purchasing or installing.