3/8" x 7/8" Pre-Insulated Copper AC Line Set

3/8" x 7/8" Pre-Insulated Copper AC Line Set

DABUND 3/8" x 7/8" pre-insulated copper AC line set is designed for compatible high-capacity air-conditioning, heat pump, VRF/VRV and refrigeration systems that specify these refrigerant tube dimensions.

The paired copper tubing combines a 3/8" tube and a 7/8" tube, equivalent to approximately 9.52 mm and 22.23 mm outside diameter. On compatible equipment, the smaller tube commonly serves as the liquid line while the larger tube serves as the suction or gas line.

High-purity copper tubing and factory-applied insulation provide a ready-to-install refrigerant piping solution for HVAC contractors, distributors, project suppliers and private-label brands. ASTM B280 copper specifications and multiple insulation configurations are available according to the ordered product.

Quick Answer: A 3/8" x 7/8" AC line set uses approximately 9.52 mm and 22.23 mm OD copper tubing for compatible HVACR systems. DABUND offers multiple coil lengths and black rubber insulation thicknesses for wholesale, project and OEM supply.

Compatibility Notice: Do not select a 3/8" x 7/8" line set solely by brand, tonnage or BTU capacity. Confirm both refrigerant pipe diameters, maximum piping length, vertical separation, refrigerant type and insulation requirements in the equipment manufacturer's installation manual.

3/8" x 7/8" AC Line Set Specifications

What Does 3/8" x 7/8" Mean on an AC Line Set?

The dimensions describe the outside diameter of the two refrigerant copper tubes. The 3/8" tube measures approximately 9.52 mm OD, while the 7/8" tube measures approximately 22.23 mm OD.

On many compatible systems, the 3/8" tube functions as the liquid refrigerant line and the 7/8" tube functions as the suction or gas return line. The exact function must follow the piping diagram for the equipment being installed.

Key Features of the 3/8" x 7/8" Copper Line Set

High-Purity Copper for HVACR Applications

High-purity copper provides good thermal conductivity, formability and corrosion resistance for professional air-conditioning and refrigeration piping applications.

ASTM B280 and C12200 specifications are available according to the ordered configuration. Buyers can confirm tubing dimensions, wall thickness and required technical documentation before placing a bulk order.

Large 7/8" Suction Line

The 7/8" tube provides a larger refrigerant return path for compatible HVAC equipment that requires this suction-line diameter. Correct sizing is important for refrigerant velocity, pressure drop, oil return and system performance.

Factory-Applied Insulation

Factory-applied insulation reduces field preparation and helps provide consistent thermal protection around the refrigerant tubing. Suitable insulation also helps control surface condensation on cold suction lines.

Multiple Coil Lengths

DABUND supplies 15 m, 20 m, 25 m, 30 m and 50 m coil options according to project and purchasing requirements. Always compare the selected length with the equipment manufacturer's maximum refrigerant piping limits.

Straight-End and Connection Options

Connection configurations can be supplied according to order requirements. Confirm whether the project requires straight tube ends, flare connections or another connection arrangement before production.

OEM Insulation Printing

Company name, tube dimensions, coil length and other product identification can be printed for distributors, OEM buyers and private-label HVAC brands.

High-Purity Copper Tubing

Black Rubber Insulation

Protective Plastic Caps

Black Rubber Insulation Performance

Closed-cell black rubber insulation helps reduce thermal transfer, moisture penetration and surface condensation around refrigerant piping. The flexible structure also makes insulated tubing easier to route through HVAC installations.

• Closed-cell structure for moisture resistance

• Thermal protection for refrigerant piping

• Helps reduce surface condensation

• Flexible construction for field routing

• UV-resistant configurations available

• Multiple insulation thicknesses available

• Selected specifications from approximately -40°C to 120°C

Thermal Protection

Suitable insulation helps reduce unwanted heat transfer between refrigerant tubing and ambient air, supporting stable system operation when the HVAC system is correctly designed.

Condensation Control

Closed-cell insulation helps limit water-vapor penetration and condensation. Correct insulation thickness and sealed joints are particularly important on the larger suction line.

Outdoor Protection

UV-resistant insulation options are available for outdoor piping sections. Additional line-set covers or mechanical protection may be required depending on local climate and installation conditions.

Insulation Testing Options

Available insulation configurations include testing related to ASTM E84, UL 94, ASTM D1056 and ASTM G21 according to the selected material specification. Buyers should verify the exact applicable test report for the ordered configuration.

Is a 3/8" x 7/8" AC Line Set Compatible With My System?

A 3/8" x 7/8" refrigerant line set is used on selected higher-capacity air-conditioning, heat pump, VRF/VRV and refrigeration systems. However, it is not universally compatible with equipment of any particular capacity or brand.

Some equipment in higher-capacity classes may specify a 3/8" liquid line and 7/8" suction line, but other equipment with similar nominal capacity can require different dimensions.

Before ordering, check the equipment data sheet or installation manual for the exact liquid-line OD, suction-line OD, minimum and maximum piping length, vertical lift and refrigerant charge requirements.

Why Correct Line Set Sizing Matters

Refrigerant piping size directly influences refrigerant velocity, pressure drop, oil return and system performance. Using tubing that does not match the equipment manufacturer's specification may affect capacity and reliability.

• Supports correct refrigerant flow

• Helps control pressure drop

• Supports proper oil return where applicable

• Helps maintain designed system capacity

• Supports long-term compressor reliability

How to Choose the Correct AC Line Set Length

Select the coil length according to the actual routing distance between indoor and outdoor equipment, while staying within the manufacturer's allowable refrigerant piping limits.

Measure the Actual Installation Route

Include horizontal runs, vertical sections, bends, wall penetrations and equipment connection points when estimating required tubing length.

Check Maximum Equivalent Length

Bends and fittings can affect equivalent piping length. Confirm both physical and equivalent-length limits in the equipment manufacturer's instructions.

Confirm Vertical Separation

Check the maximum permitted elevation difference between indoor and outdoor equipment, particularly on multi-story or rooftop installations.

Check Additional Refrigerant Requirements

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

Applications of 3/8" x 7/8" Insulated Copper Tubing

High-Capacity Split Air Conditioning

Suitable for compatible higher-capacity split AC systems that specifically require 3/8" and 7/8" refrigerant line dimensions.

Heat Pump Systems

Can be supplied for compatible heat pump installations where the specified liquid and suction line diameters match this configuration.

VRF and VRV Systems

Suitable for selected VRF/VRV refrigerant piping applications when system engineering specifications require 3/8" and 7/8" copper tubing.

Commercial HVAC Projects

Multiple coil lengths make the product suitable for compatible commercial installations requiring longer refrigerant piping routes.

Refrigeration Equipment

The tubing can also be supplied for refrigeration applications when pipe size, wall thickness, insulation and operating-pressure requirements match the system design.

Available Mini Split and HVAC Line Set Sizes

3/8" x 7/8" Line Sets for HVAC Distributors

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

The 3/8" x 7/8" configuration provides an additional stocking option for buyers serving compatible higher-capacity air-conditioning and refrigeration equipment.

OEM and Custom HVAC Line Set Supply

DABUND supports OEM and ODM production for HVAC brands, distributors and project buyers.

• Custom copper tube combinations

• 15 m / 20 m / 25 m / 30 m / 50 m and customized lengths

• Multiple insulation thickness options

• Logo and specification printing

• Private-label packaging

• Custom product identification

• Bulk production for distributors and project buyers

Why Choose DABUND AC Line Sets?

HVAC Manufacturing Experience Since 2008

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

Multiple Line Set Specifications

Multiple paired copper tube sizes, lengths and insulation thicknesses allow distributors to source different line-set configurations from one supplier.

OEM and Private-Label Support

DABUND supports insulation printing, customized packaging and other OEM requirements for HVAC brands and distributors.

Export Supply

Export packaging and commercial shipping configurations are available according to order quantity, product specification and destination requirements.

DABUND International Supply

DABUND supplies insulated copper line sets and HVAC products to international distributors, importers and professional buyers.

SGS Testing and Insulation Standards

Available insulation specifications include testing related to ASTM E84, UL 94, ASTM D1056 and ASTM G21. Buyers should confirm the applicable test documentation for the exact insulation configuration being ordered.

International HVAC Exhibitions

DABUND participates in international HVAC exhibitions to present insulated copper tubing, AC line sets and related HVAC products to industry buyers.

Frequently Asked Questions

What is a 3/8" x 7/8" AC line set?

It is a paired refrigerant copper line set containing 3/8" and 7/8" outside-diameter tubing with factory-applied insulation for compatible air-conditioning, heat pump and refrigeration systems.

What are the metric sizes of 3/8" and 7/8" copper tubing?

A 3/8" copper tube has an outside diameter of approximately 9.52 mm, while a 7/8" copper tube has an outside diameter of approximately 22.23 mm.

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

On compatible equipment, the 3/8" tube commonly serves as the liquid line and the 7/8" tube as the suction or gas line. Always verify this with the equipment manufacturer's piping specification.

What HVAC capacity uses a 3/8" x 7/8" line set?

This pipe combination is used by selected higher-capacity HVAC systems. Some systems in approximately 72,000–96,000 BTU classes may use these dimensions, but this is not a universal sizing rule.

Can I select a 3/8" x 7/8" line set by tonnage alone?

No. Line sizing depends on the equipment design, refrigerant, actual piping distance, vertical lift and manufacturer requirements. Always verify the exact model specification.

Is this line set compatible with all major HVAC brands?

Compatibility is model-specific rather than brand-wide. Equipment from the same manufacturer can use different refrigerant pipe sizes, so confirm that the exact model requires 3/8" and 7/8" tubing.

What lengths are available?

Current product information lists 15 m, 20 m, 25 m, 30 m and 50 m coil options. Customized lengths can also be discussed for OEM and bulk orders.

Can I use a long coil without checking the HVAC manual?

No. Always check the equipment manufacturer's maximum actual and equivalent piping length, vertical separation and refrigerant-charge requirements before choosing the coil length.

Does a longer line set require additional refrigerant?

It may. Many systems include a factory refrigerant charge for only a specified standard piping length. Additional refrigerant must follow the charging instructions for the exact equipment model.

Is the insulation suitable for outdoor installation?

UV-resistant insulation configurations are available for outdoor sections. Additional mechanical or line-cover protection may be required depending on climate and project conditions.

What insulation thicknesses are available?

Available black rubber insulation thicknesses include 8 mm, 9 mm, 10 mm, 13 mm, 19 mm and 25.4 mm depending on the selected configuration.

What pressure can the copper line set handle?

The allowable working and test pressure depends on tube diameter, wall thickness, copper specification and product configuration. Buyers requiring a specific pressure rating should confirm the applicable technical data for the exact tubing ordered.

Can DABUND customize the 3/8" x 7/8" line set?

Yes. OEM and ODM options include coil length, insulation thickness, product identification, logo printing and private-label packaging.

Who should install the refrigerant line set?

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