Yes, it is possible to braze mini split line sets, but it is not a common practice due to warranty concerns. Brazing is a process that involves melting a filler metal to join two pieces of metal, while flaring is a process that involves deforming the end of a copper tube to create a larger surface area for a connection. Brazing can provide a stronger and more durable connection than flaring, but it may not be accepted by the manufacturer in a warranty situation.
Preparing the Mini Split Line Sets for Brazing
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Flare the Large Suction Line Tube: Begin by flaring the large suction line tube and connecting it to the outdoor unit. This ensures a secure and leak-free connection at the outdoor unit.
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Cut Off Flare Connectors and Ream Copper Tubes: Next, cut off the flare connectors from the indoor unit copper stubs and ream the copper tubes. Reaming the tubes removes any burrs or imperfections, creating a smooth surface for the brazing process.
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Swage the Copper Stubs: Swage the copper stubs from the indoor unit, which involves expanding the end of the tube to create a larger surface area for the brazing connection. This step ensures a tight and secure fit when the line set tubes are run into place.
Brazing the Mini Split Line Sets
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Connect Nitrogen Flow Regulator: Connect a flow regulator to a nitrogen tank and set it to flow at 2-3 CFH (cubic feet per hour). Then, connect the nitrogen hose to the outdoor unit’s vapor service port. This will help prevent oxidation during the brazing process.
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Braze the Swage Joints: Using a small brazing tip and 15% silver brazing rod, carefully braze the swage joints. The silver brazing rod will melt and flow into the joint, creating a strong and leak-proof connection.
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Disconnect Nitrogen and Flare Liquid Line: Once the brazing is complete, disconnect the nitrogen hose and flare the small, low-pressure liquid line. Then, connect the flared liquid line to the outdoor unit’s flare connection.
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Tighten Flare Connections: Tighten all flare connections to the specified torque value, as per the manufacturer’s instructions. This ensures a secure and leak-free connection.
Pressure Testing the System
- Pressure Test the System: After completing the brazing and flaring, it is essential to pressure test the system to check for any leaks. This step is crucial to ensure the integrity of the refrigerant system and prevent potential issues down the line.
Important Considerations
It is important to note that while brazing can create a stronger and more durable connection than flaring, it may not be accepted by the manufacturer in a warranty situation. Technicians should verify this with the manufacturer of the particular equipment they are installing.
Additionally, when brazing copper line sets, it is crucial to flow nitrogen or another inert gas through the tubes to prevent oxidation from occurring inside the line set. Oxidation can lead to blockages and other issues within the refrigerant system.