HVAC Flare Coupler Connectors for Traditional Refrigerant Line Sets | 1/4 x 3/8, 1/4 x 1/2, 1/4 x 5/8, 3/4 x 3/8 Brass Line Set Unions for Mini Split & Residential HVAC Systems

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HVAC flare coupler connectors for joining two traditional flared refrigerant lines in mini split and residential HVAC applications. These solid brass flare union fittings are desig ned for use when combining or extending compatible traditional line sets that use standard flare connections. These fittings are commonly used in mini split installations, heat pump systems, ductless air conditioner systems, and other residential HVAC applications where properly sized flare refrigerant lines need to be connected together. Available sizes cover many common line set combinations used across major brands. Important: These connectors are for traditional HVAC flare line sets only. They are not for use on MRCOOL DIY Series, the original true DIY pre-charged system design. Even though some brands may market similar fittings as “DIY,” any HVAC refrigerant system that is opened to atmosphere must be properly installed using approved HVAC practices, including evacuation to remove oxygen, air, and moisture. Failure to properly evacuate the system can introduce contamination, cause serious system damage, reduce performance, and may void the factory warranty. Available Sizes & Common Applications Connector Size Compatible Copper Pipe OD Common HVAC Application 1/4" x 3/8" 1/4" OD + 3/8" OD Common for 6k, 9k, and 12k mini split systems including many MRCOOL and other brand applications using 1/4" liquid and 3/8" suction lines 1/4" x 1/2" 1/4" OD + 1/2" OD Common for 18k mini split systems including many MRCOOL and other compatible brands using 1/4" liquid and 1/2" suction lines 1/4" x 5/8" 1/4" OD + 5/8" OD Used on select higher-capacity residential ductless and heat pump applications that require 1/4" liquid and 5/8" suction line connections 3/4" x 3/8" 3/4" OD + 3/8" OD Common for 24k and 36k air handler applications using 3/8" liquid and 3/4" suction lines Series Specifications Connector Model Compatible Copper Pipe Outer Diameter 1/4 1/4in (6.35mm) 3/8 3/8in (9.52mm) 1/2 1/2in (12.70mm) 5/8 5/8in (15.88mm) 3/4 3/4in (19.05mm) Key Features Designed to join two traditional flared HVAC refrigerant lines Compatible with many mini split, ductless, and residential HVAC systems Solid brass construction for durability and dependable fitment Available in common line set size combinations used across multiple brands Ideal for properly installed and evacuated systems using standard flare connections Suitable for use with all common residential refrigerants when used in a properly engineered and properly installed system Common Search Uses Customers often search for these fittings as mini split flare couplers, HVAC flare union fittings, refrigerant line coupler connectors, brass flare connectors for line sets, ductless mini split line set unions, or flare fittings for traditional refrigerant lines. Important Compatibility Note Always verify your system’s required liquid line size and suction line size before ordering. These fittings are sized by the copper tubing outside diameter used in standard HVAC line sets. Proper installation, torque, evacuation, pressure testing, and charging procedures should always be followed according to manufacturer requirements and accepted HVAC industry practices. Not for MRCOOL DIY Series These coupler connectors are not compatible with the original MRCOOL DIY Series pre-charged Quick Connect system. They are intended only for traditional flare-type refrigerant line sets. Show more