Cooper & Hunter line set sizes
Short answer: Cooper & Hunter 9,000–12,000 BTU mini-splits use a 1/4" × 3/8" line set, 18,000 BTU units use 1/4" × 1/2", and 24,000–36,000 BTU units use 3/8" × 5/8" — standard field-flared sizes matching the pre-flared kits Cooper & Hunter sells. Always confirm the sizes against your unit's installation manual.
The right line set diameter for your Cooper & Hunter mini-split by capacity — plus what the brand's pre-flared kits do and don't do for a DIY install. Prefer to size by run length too? Use the size calculator.
Cooper & Hunter line set size by capacity
Line set diameter is set by your system's capacity. Cooper & Hunter follows the standard mini-split pairings, so match your unit's BTU rating to the liquid-and-gas pair below — these match the kit sizes Cooper & Hunter sells.
| Cooper & Hunter 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 pre-flared, insulated line sets in all three sizes Cooper & Hunter uses: 1/4" × 3/8" for 9,000–12,000 BTU, 1/4" × 1/2" for 18,000 BTU, and 3/8" × 5/8" for 24,000–36,000 BTU. 16 ft and 25 ft, open for preorder.
Cooper & Hunter sells matching installation kits in all three sizes — 1/4" × 3/8", 1/4" × 1/2", and 3/8" × 5/8" — in 16, 25, and 50 ft lengths, with pre-flared, pre-insulated copper and the control wire. Buy the diameter that matches your unit, in a length sized to your run. Always confirm the sizes against your manual.
Pre-flared kits help — but it's still a vacuum install
Cooper & Hunter is a popular DIY-friendly brand, and its pre-flared, pre-insulated kits remove one of the trickier steps. But a C&H is still a standard field-flared system, not quick-connect: you connect the flares and pull a vacuum to remove air and moisture before opening the service valves. Plan on a vacuum pump and typically EPA 608 certification. For a true no-vacuum route, that's a pre-charged quick-connect brand such as MRCOOL DIY — see pre-charged line sets.
Cooper & Hunter line set length limits
Diameter is only half the spec. Your Cooper & Hunter 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 |
Cooper & Hunter's limits depend on capacity and generation. Single-zone systems allow roughly 82 ft of line on 9,000–12,000 BTU units, with about 33–49 ft of vertical separation, and about 98 ft on 18,000 BTU units; the newer R-454B MIA 24,000 BTU jumps to about 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. Cooper & Hunter lists a minimum run of about 10 ft to limit noise and vibration.
Stocked lengths and refrigerant
Because Cooper & Hunter uses standard line sets, you size to your run — common stocked lengths are 16, 25, 35, and 50 ft.
Match the refrigerant. Cooper & Hunter sells both R-410A and newer R-454B systems 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 Cooper & Hunter model's line set size
- Identify the series and capacity. Note the model number and BTU — Cooper & Hunter sizing follows the capacity, but always verify the exact figures and the included kit size.
- Check the installation manual. It lists the exact liquid and gas diameters, the maximum line length, and the refrigerant for your model — the final word.
Common questions
What size line set does a Cooper & Hunter 12,000 BTU use?
A Cooper & Hunter 12,000 BTU mini-split uses a 1/4" liquid line with a 3/8" gas line, the same pair as the 9,000 BTU models. Cooper & Hunter sells matching pre-flared kits in this size. Confirm against your model's installation manual.
Do Cooper & Hunter mini-splits use flared or quick-connect line sets?
Cooper & Hunter uses standard field-flared line sets, not pre-charged quick-connect. They sell pre-flared, pre-insulated kits to make it easier, but you still pull a vacuum before opening the service valves, so the install needs a vacuum pump and typically EPA 608 certification.
What size line set does a Cooper & Hunter 24,000 BTU use?
A Cooper & Hunter 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 steps down to 1/4" × 1/2". Verify against your unit's manual.
What refrigerant do Cooper & Hunter mini-splits use?
Cooper & Hunter sells both R-410A and newer R-454B systems, with R-454B units pre-charged for up to about 25 ft of line set as the industry phases out R-410A. Match your line set, tools, and any added charge to your unit's refrigerant.
What is the minimum line set length for a Cooper & Hunter mini-split?
Cooper & Hunter 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 Cooper & Hunter mini-split?
It depends on capacity and generation. Cooper & Hunter single-zone systems allow roughly 82 ft of line on 9,000–12,000 BTU units and about 98 ft on 18,000 BTU units; the newer R-454B MIA 24,000 BTU jumps to about 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
This page provides general guidance on Cooper & Hunter mini-split line set sizing based on published Cooper & Hunter specifications. Exact line diameters, included kit size, 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.