1/4" x 3/8" Mini Split Air Conditioner Line Set

1/4" x 3/8" Mini Split Air Conditioner Line Set

DABUND 1/4" x 3/8" Mini Split Air Conditioner Line Set is a pre-insulated twin copper refrigerant piping solution for compatible ductless mini split air conditioners, heat pumps and split HVAC systems.

The paired line set combines a 1/4" copper tube and a 3/8" copper tube, equivalent to approximately 6.35 mm and 9.52 mm outside diameter. Multiple coil lengths are available for distributors, installers and project buyers.

On compatible mini split systems, the 1/4" tube commonly serves as the liquid line while the 3/8" tube serves as the suction or gas line. Exact refrigerant pipe sizing should always be confirmed against the installation manual for the specific indoor and outdoor equipment combination.

High-purity copper tubing is combined with factory-applied white PE insulation for thermal protection and condensation control. ASTM B280 and C12200 DHP copper specifications are available according to the ordered configuration.

Quick Answer: This is a 1/4" x 3/8" pre-insulated mini split AC line set using approximately 6.35 mm and 9.52 mm OD copper tubing. Multiple lengths, insulation thicknesses, OEM printing and private-label options are available.

Compatibility Notice: Do not select a mini split line set only by BTU capacity, tonnage or equipment brand. Verify the required liquid-line size, suction-line size, permitted piping length, vertical separation, refrigerant type and charging requirements for the exact HVAC model.

1/4" x 3/8" Mini Split Line Set Specifications

Key Features of the 1/4" x 3/8" Mini Split AC Line Set

1/4" Liquid Line and 3/8" Suction Line

On compatible mini split air-conditioning systems, the smaller 1/4" tube commonly functions as the liquid refrigerant line while the larger 3/8" tube functions as the suction or gas return line.

Their approximate outside diameters are 6.35 mm and 9.52 mm. Always verify both refrigerant-line dimensions before ordering because different equipment models can use different pipe sizes.

Multiple Coil Lengths for Different Installations

DABUND supplies multiple coil lengths so distributors and project buyers can match different indoor-to-outdoor equipment distances without relying on one fixed line-set length.

Available production lengths include 15 m, 20 m, 25 m, 30 m and 50 m, with additional customization subject to the ordered specification.

C12200 DHP Copper Tubing

High-purity copper provides good formability, thermal conductivity and corrosion resistance for professional HVAC refrigerant piping.

ASTM B280 and C12200 DHP copper specifications are available according to the ordered configuration. Buyers requiring specific wall thickness or pressure performance should confirm the applicable technical data before production.

Factory-Applied White PE Insulation

Factory-applied white PE insulation helps reduce field preparation while providing thermal protection and supporting condensation control around the copper refrigerant piping.

Multiple Insulation Thicknesses

Insulation thickness options include 8 mm, 9 mm, 10 mm, 13 mm, 19 mm and 25.4 mm according to project requirements and ordered configuration.

Single Suction-Line Options

In addition to paired 1/4" x 3/8" line sets, single insulated suction-line configurations can be discussed for replacement, OEM and project requirements. Required tube diameter, insulation and coil length should be confirmed before ordering.

OEM Printing and Private Label

Company name, copper tube dimensions, coil length and other product identification can be printed on the insulation for HVAC distributors, wholesalers and private-label brands.

High-Purity Copper Tubing

White PE Insulation

Protective Plastic Caps

White PE Multi-Layer Insulation

The white PE insulation uses a multilayer structure designed to help reduce thermal transfer, moisture penetration and mechanical wear during transport and HVAC installation.

Embossed PE Outer Layer

The embossed PE outer layer helps protect the insulation from abrasion and normal handling damage. UV-resistant configurations are available for outdoor refrigerant piping sections.

IXPE Foam Middle Layer

The foam middle layer helps reduce heat transfer while providing cushioning and moisture resistance around the copper tube.

Closed-Cell Inner Layer

The closed-cell inner structure helps limit water-vapor penetration and supports condensation control around cold refrigerant piping.

Insulation Pipe Production

Insulated Pipe Warehouse

Closed-Cell Inner Insulation

Insulation Performance for Mini Split Refrigerant Lines

Thermal Protection

Suitable insulation helps reduce unwanted heat transfer between refrigerant piping and surrounding air, supporting the intended operating conditions of the HVAC system.

Condensation Control

Closed-cell insulation helps reduce water-vapor penetration and surface condensation. Insulation joints should be properly sealed, particularly in warm and humid environments.

Mechanical Protection

The outer insulation layer helps protect the tubing from normal abrasion while refrigerant lines are routed through walls, ceilings, attics and mechanical spaces.

UV-Resistant Options

UV-resistant insulation configurations are available where refrigerant piping includes outdoor sections. Additional protective line-set covers may be used where greater weather or mechanical protection is required.

Insulation Testing Options

Available insulation specifications include testing related to ASTM E84, UL 94, ASTM D1056, ASTM G21, ASTM C1427 and UL 723 according to the selected material configuration. Buyers should confirm the applicable documentation for the exact product being ordered.

Choosing the Correct Mini Split Line Set Length

Selecting the correct refrigerant line length depends on the actual route between the indoor and outdoor units rather than straight-line distance alone.

The route may pass through walls, ceilings, attics, service spaces or different building levels. Allow sufficient tubing for bends, connections and required service positioning while remaining within the equipment manufacturer's piping limits.

Check Maximum Actual Piping Length

Each mini split model has its own maximum permitted refrigerant piping length. Verify this limit before selecting a coil length.

Check Equivalent Piping Length

Bends and routing conditions may affect equivalent piping length. Follow the equipment manufacturer's calculation method where equivalent-length limits are specified.

Verify Vertical Separation

If indoor and outdoor units are installed at different elevations, check the maximum vertical separation allowed for the exact equipment model.

Confirm Additional Refrigerant Requirements

Some mini split systems include a factory refrigerant charge for only a specified standard piping length. Longer installations may require additional refrigerant according to the manufacturer's charging instructions.

Is 1/4" x 3/8" Compatible With My Mini Split?

The 1/4" x 3/8" combination is commonly used on selected smaller-capacity ductless mini split air conditioners and heat pumps.

Some equipment around 9,000–12,000 BTU may use a 1/4" liquid line and 3/8" suction line, but this is not a universal sizing rule.

Equipment with similar nominal cooling capacity can use different pipe diameters. Always verify the exact indoor and outdoor equipment combination before purchasing the line set.

Applications of 1/4" x 3/8" Mini Split Line Sets

Ductless Mini Split Air Conditioners

Suitable for compatible ductless mini split systems that specifically require 1/4" and 3/8" refrigerant pipe dimensions.

Mini Split Heat Pumps

Can be supplied for compatible heat pump systems using the same paired refrigerant tube dimensions.

Residential HVAC Installation

Multiple coil lengths provide installers and distributors with options for different indoor-to-outdoor routing distances in residential HVAC projects.

Light-Commercial HVAC Projects

The line set can also be supplied for compatible light-commercial applications where pipe size, length and insulation requirements match the equipment design.

Available Mini Split Line Set Sizes

Mini Split Line Set Supply for Distributors

DABUND supplies pre-insulated copper line sets to HVAC distributors, wholesalers, importers, contractors, project suppliers and private-label brands.

The 1/4" x 3/8" configuration provides a common stocking option for buyers serving compatible ductless mini split and heat pump installations, while multiple available lengths allow inventory to cover different installation distances.

OEM and Custom Mini Split Line Sets

DABUND supports OEM and ODM supply for HVAC distributors, importers and private-label brands.

• Custom copper tube combinations

• Multiple coil lengths

• Custom insulation thickness

• Single insulated suction-line options

• Company name and specification printing

• Private-label packaging

• Custom product identification

• Bulk supply for distributors and project buyers

Why Choose DABUND Mini Split Line Sets?

HVAC Manufacturing Experience Since 2008

DABUND has manufactured HVAC components since 2008, supplying mini split line sets, insulated copper pipe and related HVAC products to international customers.

Multiple Sizes, Lengths and Insulation Options

Multiple copper tube combinations, coil lengths and insulation thicknesses allow distributors to source different refrigerant piping configurations according to local market requirements.

OEM and Private-Label Support

Insulation printing, product identification and packaging can be customized for HVAC brands, wholesalers and distributors.

DABUND Factory

DABUND manufactures insulated copper pipe, mini split line sets, aluminum pipe and related HVAC components for international B2B customers.

SGS Testing and Insulation Standards

Available insulation configurations include testing related to ASTM E84, UL 94, ASTM D1056 and ASTM G21 according to the selected material specification. Buyers should confirm the applicable documentation for the exact insulation being ordered.

International HVAC Exhibitions

DABUND participates in international HVAC exhibitions to present mini split line sets, insulated copper tubing and related HVAC products to distributors, importers and professional buyers.

Frequently Asked Questions

What is a 1/4" x 3/8" mini split air conditioner line set?

It is a paired refrigerant piping system containing 1/4" and 3/8" outside-diameter copper tubing with factory-applied insulation for compatible mini split air conditioners and heat pumps.

What are the metric sizes of 1/4" and 3/8" copper tubing?

A 1/4" copper tube has an outside diameter of approximately 6.35 mm, while a 3/8" copper tube has an outside diameter of approximately 9.52 mm.

Which tube is the liquid line and which is the suction line?

On compatible systems, the 1/4" tube commonly serves as the liquid line and the 3/8" tube as the suction or gas line. Always confirm this with the equipment manufacturer's documentation.

What mini split capacity uses a 1/4" x 3/8" line set?

Some mini split systems around 9,000–12,000 BTU may use this tube combination, but this is not universal. Similar-capacity equipment can require different refrigerant-line dimensions.

Can I select the line set by BTU or tonnage alone?

No. Refrigerant piping depends on equipment design, refrigerant type, line length, vertical separation and the manufacturer's specifications.

What lengths are available for the 1/4" x 3/8" line set?

Standard production options include 15 m, 20 m, 25 m, 30 m and 50 m. Additional lengths can be discussed for OEM and bulk orders.

How do I choose the correct mini split line-set length?

Measure the actual refrigerant piping route and verify the equipment manufacturer's maximum actual length, equivalent length and vertical separation before selecting the coil length.

Does a longer mini split line require additional refrigerant?

It may. Many systems include a factory refrigerant charge for only a specified standard line length. Follow the manufacturer's charging instructions for the exact model.

What insulation is used on this line set?

This product family is available with white PE closed-cell insulation designed to provide thermal protection and help control condensation.

What insulation thicknesses are available?

Available insulation thickness options include 8 mm, 9 mm, 10 mm, 13 mm, 19 mm and 25.4 mm depending on the ordered configuration.

Is UV-resistant insulation available?

Yes. UV-resistant insulation configurations are available for installations that include outdoor refrigerant piping sections.

Can DABUND supply only the insulated suction line?

Yes, selected single insulated suction-line configurations can be discussed for replacement, OEM and project requirements. Confirm the required tube diameter, insulation and length before ordering.

What pressure rating does the copper tubing have?

Allowable working and test pressure depends on copper tube diameter, wall thickness, material specification and ordered configuration. Buyers requiring a specific pressure value should confirm the applicable technical data before ordering.

Can DABUND customize the mini split line set?

Yes. OEM and ODM options include copper tube combinations, coil lengths, insulation thickness, insulation printing, product identification and private-label packaging.

Can I get samples before placing a bulk order?

Yes. According to the current product information, DABUND can provide three sample pieces for evaluation, with the buyer covering express shipping costs. View sample information.

What payment terms are available?

Available payment methods can include T/T, L/C at sight and credit card. Final payment terms depend on the commercial agreement.

What delivery terms are available?

International trade terms can include EXW, FOB, CFR and CIF according to the buyer's logistics requirements.

What is the typical delivery time?

Current product information lists typical delivery at approximately 15–20 days. Actual lead time depends on quantity, product specification, customization and production schedule.

Who should install the mini split refrigerant line set?

Refrigerant piping, flare or brazed connections, pressure testing, evacuation and refrigerant charging should be completed by qualified HVAC personnel according to local requirements and the equipment manufacturer's instructions.