A flare nut connection is a mechanical fitting used to join the copper line sets to the indoor and outdoor units. It creates a high-pressure seal that prevents refrigerant leaks without the need for soldering or brazing. These connections are a standard feature in our Installation Kits. To ensure a perfect seal, it is critical that the installer uses a proper flaring tool and a torque wrench. If these nuts are over-tightened or under-tightened, the system may lose its refrigerant charge over time. We provide Technical Data and guides to help installers understand the correct torque specifications. For those who want to avoid flaring altogether, our DIY mini-splits use pre-flared, quick-connect technology. These small brass components are vital for the long-term reliability and performance of your HVAC system. Always check for oily residue around these connections, as that can be a sign of a slow leak.