Restrictions On Pipe Length - Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook

[7] Restrictions on Pipe Length

The refrigerant pipe from the outdoor unit is branched at the pipe end, and each branch is then connected to an indoor unit.
Flare connections are used for the pipes on the indoor units and for the liquid pipes on the outdoor units. Flange connections
are used for gas pipes on the outdoor units. Branched sections are brazed together.
WARNING
Do not let refrigerant (R410A) leak in the presence of an
open flame or other heat source. When exposed to an open
flame or other heat source, refrigerant will break down, gen-
erate poisonous gas, and pose a risk of gas poisoning. Do
not weld in a confined space. Perform an air tightness test
at the completion of pipe work.
CAUTION
Do not use the existing refrigerant piping.
A large amount of chlorine that may be contained in the re-
sidual refrigerant and refrigerating machine oil in the exist-
ing piping may cause the refrigerating machine oil in the
new unit to deteriorate.
Use refrigerant pipes made of phosphorus deoxidized
copper. Keep the inner and outer surfaces of the pipes
clean and free of such contaminants as sulfur, oxides,
dust, dirt, shaving particles, oil, and water.
These types of contaminants inside the refrigerant pipes
may cause the refrigerant oil to deteriorate.
Only use the type of refrigerant (R410A) that is indicat-
ed on the unit when installing or reinstalling the unit.
Infiltration of any other type of refrigerant or air into the unit
may adversely affect the refrigerant cycle and may cause
the pipes to burst or explode.
Store the pipes to be installed indoors, and keep both
ends of the pipes sealed until immediately before braz-
ing. (Keep elbows and other joints wrapped in plastic.)
Infiltration of dust, dirt, or water into the refrigerant system
may cause the refrigerating machine oil to deteriorate or
cause the unit to malfunction.
Charge liquid refrigerant (as opposed to gaseous re-
frigerant) into the system.
If gaseous refrigerant is charged into the system, the com-
position of the refrigerant in the cylinder will change and
may result in performance loss.
Do not use a charging cylinder.
If a charging cylinder is used, the composition of the refrig-
erant will change, and the unit may experience power loss.
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[ II Restrictions ]