Copyright Goodheart-Willcox Co., Inc. Chapter 32 Residential Split Air-Conditioning Systems 823 10 studs. Be sure to level the wall bracket. If the bracket is not level, the unit will look crooked on the wall and the con- densate drain may not function correctly. After the wall bracket is installed, drill a 3″ hole in the wall for the line set. Use the installation guide to deter- mine the hole’s location. See Figure 32-39. Many indoor units are mounted on walls, near the ceil- ing. It can be difficult to hold the unit in place while neces- sary wiring and other connections are made. Once the wall plate is secured into place, a bracket can be attached to hold the indoor unit in place, Figure 32-40. Ductless systems have minimum and maximum lengths for line sets. Line sets are also limited to a maxi- mum vertical change. Always measure and record the line set lengths and verify that the measurements fall in the acceptable range for the product. The condensate drain is generally 5/8″ flexible hose. Do not use 3/8″ clear plastic condensate tubing in a duct- less system. This smaller tubing may bend, resulting in blockages. Any condensate drain issues are major prob- lems with a ductless system because if the drain pan overflows, it will immediately cause damage in a living area. Slope condensate drain hose a minimum of 1/4″ per foot. If a gravity drain is not possible, install a condensate pump. Flared connections are used for the refrigerant line connections. (Flared connections are discussed in Chapter 8, Working with Tubing and Piping.) Poor flared connections are a common problem with ductless sys- tems, so be sure to follow best practices when making these connections. After cutting refrigerant tubing, point the cut end of the tubing toward the ground as you deburr or ream the inside edge. This way, any small tubing particles will fall out of the tubing. Ductless systems do not have a filter- drier to eliminate contaminants, so extra care is required. When making the flared connection, use a torque wrench to torque the flare nut to the specification in the installa- tion manual. After the refrigerant line connections, wiring connec- tions, and drain connections have been made, the system is ready to be commissioned. First, the system is pressure tested. Follow the manufacturer’s instructions, but a pres- sure test is likely to be in the range of 500 psi for 24 hours. Using nitrogen for pressure test rather than air is prefer- able because using air introduces additional moisture into the system. Once the system passes the pressure test, the system is evacuated using the triple-evacuation method. The third evacuation generally must pull a vacuum of less than 500 microns. This evacuation is critical to ensure that mois- ture and any other contaminants are cleared from the sys- tems before refrigerant is added. Charge with refrigerant after the evacuation is complete. Manufacturer’s Training for Ductless Systems Manufacturer’s training is the best way to prepare for installing and servicing ductless systems. These systems use proprietary control systems, and installation and service guidelines vary from system to system. The more training you receive, the better your installations and service will be. Pro Tip RectorSeal Figure 32-40. This wall bracket allows an indoor unit to be securely held in place while connections are made. Indoor unit Line set cover Line set 3" hole in exterior wall Shcherbakov Ilya/Shutterstock.com Figure 32-39. A line set from the outdoor unit passes through the building’s exterior wall and connects to the indoor unit.