Which refrigerant line in a typical residential split system installation is normally insulated?

In a typical residential split system installation, the suction line is insulated for a critical reason: to prevent condensation and energy loss. The suction line carries refrigerant in a gaseous state from the evaporator coil back to the compressor. As this gas moves through the line, it can be very cold, especially during the cooling process. If the suction line is not insulated, the cold surface can lead to moisture in the air condensing on it, which could drip and potentially cause water damage.

Insulation also helps to maintain the efficiency of the system by minimizing heat gain along the suction line, allowing the refrigerant to stay colder as it travels back to the compressor. This insulation ensures that the system operates effectively, enhances energy efficiency, and prolongs the life of the equipment. In contrast, the other lines mentioned, such as the liquid line and discharge line, have different operating temperatures and roles that do not require insulation in the same way.