Mini-split line sets

Mini-split line sets for every system

A mini-split line set (often written as one word, "lineset") is the pair of copper tubes that connects the indoor air handler to the outdoor condenser, carrying refrigerant to move heat without ductwork. The smaller liquid line carries cool, high-pressure refrigerant; the larger suction line returns low-pressure gas to the compressor. Because a ductless system moves heat with refrigerant instead of air, the line set has to be sized and insulated correctly from the start.

Single-zone line sets

For bedrooms, offices, additions, and small living spaces, single-zone mini-splits use a 1/4" liquid line paired with a 3/8" to 5/8" suction line. Our pre-insulated sets come ready to install in the practical lengths most homeowners and pros reach for — 15, 25, 35, and 50 ft.

Multi-zone systems

Multi-zone systems connect several indoor heads to one outdoor unit, so they often call for larger-diameter suction lines and branch-box-friendly routing. Each line still has to match the manufacturer's specified diameter and stay within that unit's minimum and maximum length limits — size every head correctly and route each line cleanly.

Commercial and light-commercial

Rooftop, exterior-wall, and long-exposure runs demand durable copper, heavy insulation, and a UV-resistant outer jacket to resist weather, abrasion, and heat loss. For any demanding AC or heat-pump job, look for high-pressure-rated copper engineered for modern refrigerants.

Choose the right line set size

The right diameter and length keep the system efficient and protect oil return — and they're set by your equipment, not by preference. Always confirm your unit's installation manual for its approved diameter, length, and vertical-lift limits before you buy.

A small unit close to the condenser often runs a 1/4" liquid with a 3/8" or 1/2" suction line, with many standard installs capped around 50 ft. Larger rooms and open floor plans usually step up to 3/8" × 5/8" and can reach roughly 75 ft when the manufacturer approves it. Lines that are too short, too long, or the wrong diameter hurt efficiency and oil return, so size by diameter and length first. Know your BTU and run length? Use the size calculator, or browse the full line set size chart.

What quality line sets are made of

A dependable line set starts with clean copper, consistent insulation, and a jacket that holds up indoors and out.

C12200 copper

Quality tubing is C12200 phosphorus-deoxidized copper — the industry standard for air conditioning and refrigeration — for strong thermal conductivity and corrosion resistance. Look for copper that meets ASTM B280 for AC service and is rated for today's refrigerants, both R-410A and the newer R-454B replacing it, typically pressure-rated to around 700 PSI.

Closed-cell foam insulation

On a quality set, both copper lines are individually wrapped in closed-cell elastomeric foam to prevent condensation and thermal loss. UV-retardant insulation holds up in exposed areas, and common wall thicknesses — 3/8", 1/2", and 5/8" — let you match the insulation to the job.

Protective outer jacket

A UV-resistant, tear-resistant jacket shields the copper and insulation from sunlight and jobsite damage as the line passes through walls and along exterior routes. Coated insulation that needs no extra cover speeds up the install and looks cleaner when it's done.

Installing and connecting a line set

Most residential line sets use a 45° flare and flare nuts to make a serviceable seal between the copper and the equipment; on a traditional install, a vacuum pump removes air and moisture from the lines before the refrigerant is released. Run the line along joists or walls with insulated clamps, support long spans, and avoid sharp bends, kinks, or rubbing points that can weaken the copper. A no-vacuum, pre-charged "quick-connect" option also exists — its fittings connect without brazing or a vacuum pump, which helps where open-flame work isn't practical. See our full guide to pre-charged line sets →

Shop mini-split line sets

Browse pre-insulated copper line sets in the most common mini-split sizes and lengths. Sort by diameter and length above, match your equipment's spec, and order the set that fits your system. Not sure what you need? Find your size in seconds, then add the matching line set to your cart.