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Part 3 - System Design and Installation 
5.7 Piping Connections between Outdoor Units 
The  piping  connecting  the  outdoor  units  should  be  horizontal  and  must  not  be  higher  than  the  refrigerant  outlets.  If 
necessary, to avoid obstacles the piping may be vertically offset below the outlets. When inserting a vertical offset to avoid 
an obstacle, the whole outdoor piping should be offset, rather than just the section adjacent to the obstacle. Refer to Figure 
3-5.10. 
Figure 3-5.10: Piping connections between outdoor units 
 
Outdoor piping should be installed in a metal casing to protect against exposure to sunlight, rain, wind and other potential 
causes of damage. 
 
5.8 Pipe Flushing 
5.8.1 Purpose 
To remove dust, other particles and moisture, which could cause compressor malfunction if not flushed out before the 
system is run, the refrigerant piping should be flushed using nitrogen. As described in Part 3, 5.1.1 “Installation procedure”, 
pipe  flushing  should  be  performed  once  the  piping  connections  have  been  completed  with  the  exception  of  the  final 
connections to the indoor units. That is, flushing should be performed once the outdoor units have been connected but 
before the indoor units are connected.