Refrigerant Piping Installation; Caution - Mitsubishi Electric CITY MULTI PURY-P-THMU-A Installation Manual

9. Refrigerant piping installation

The pipe is connected via a terminal-branch type connection in which refrigerant
piping from the outdoor unit is branched at the terminal and is connected to each
of the indoor units.
The method of pipe connection is as follows: flare connection for the indoor
units, low-pressure pipes and high-pressure pipes for outdoor units, brazed
connection. Note that the branched sections are brazed.
Warning:
Always use extreme care to prevent the refrigerant gas from leaking while
using fire or flame. If the refrigerant gas comes in to contact with a flame
from any source, such as a gas stove, it breaks down and generates
a poisonous gas which can cause gas poisoning. Never weld in an
unventilated room. Always conduct an inspection for gas leakage after
installation of the refrigerant piping has been completed.

9.1. Caution

This unit uses refrigerant R410A. Follow the local regulations on materials and
pipe thickness when selecting pipes. (Refer to the table on the below.)
1 Use the following materials for refrigeration piping.
• Material: Use copper alloy seamless pipes made of phosphorus
deoxidized copper. Ensure the inner and outer surfaces of the pipes
are clean and free from hazardous sulfur, oxide, dusts, shaving
particles, oils, and moisture (contamination).
• Size: Refer to item 9.2. for detailed information on refrigerant piping
system.
2 Always observe the restrictions on the refrigerant piping (such as rated
length, height difference, and piping diameter) to prevent equipment failure
or a decline in heating/cooling performance.
3 Do not install outdoor unit piping when it is raining.
4 Commercially available piping often contains dust and other materials.
Always blow it clean with a dry inert gas.
5 Use care to prevent dust, water or other contaminants from entering the
piping during installation.
6 Reduce the number of bending portions as much as possible, and make
bending radius as big as possible.
7 For indoor and outdoor branching and merging section, be sure to use the
following twinning pipe sets and merge pipe sets (sold separately).
Indoor Twinning Pipe Indoor Junction Pipe Kit
Kit model
Line branch
Total indoor model
Lower stream unit model
Less than 30 in total
CMY-Y102S-G2
Outdoor Twinning Kit
model
Total outdoor model
P144 ~ P240
CMY-R100VBK
Copper pipe size and radial thickness for R410A CITY MULTI.
Radial thickness
Size (mm) Size (inch)
(mm)
ø6.35 ø1/4" 0.8
ø9.52 ø3/8" 0.8
ø12.7 ø1/2" 0.8
ø15.88 ø5/8" 1.0
*ø19.05 ø3/4" 1.2
*ø19.05 ø3/4" 1.0
ø22.2 ø7/8" 1.0
ø25.4 ø1" 1.0
ø28.58 ø1-1/8" 1.0
ø31.75 ø1-1/4" 1.1
ø34.93 ø1-3/8" 1.2
ø41.28 ø1-5/8" 1.4
* Both pipe types can be used for pipe size ø19.05 (3/4 inch) for R410A air
conditioner.
8 Use an adapter if a specified refrigerant pipe has a different diameter from
that of a branching pipe.
9 Braze only with non-oxide brazing material for piping. Failure to do so
may damage the compressor. Be sure to perform the non-oxidation
brazing with a nitrogen purge.
Do not use any commercially available anti-oxidizing agent since it may
cause pipe corrosion and degrading of the refrigerant oil.
Please contact Mitsubishi Electric for more details.
(Refer to item 10.2. for details of the piping connection and valve operation)
8
model
P72 ~ P96
CMY-R160-J
Radial thickness
Pipe type
(mil)
32 Type-O
32 Type-O
32 Type-O
40 Type-O
48 Type-O
40 Type-1/2H or H
40 Type-1/2H or H
40 Type-1/2H or H
40 Type-1/2H or H
44 Type-1/2H or H
48 Type-1/2H or H
56 Type-1/2H or H
0 Always insulate the piping properly. Insufficient insulation will result in a
decline in heating/cooling performance, water drops from condensation
forming and other such problems (Refer to item 10.4 for thermal insulation of
refrigerant piping).
a When connecting the refrigerant piping, make sure the valve of the outdoor
unit is completely closed (the factory setting). Do not operate it until the
refrigerant piping for the outdoor, indoor units and BC controller has
been connected, a refrigerant leakage test has been performed, and the
evacuation process has been completed.
b Never use refrigerant to perform an air purge. Always evacuate using a
vacuum pump.
c Be sure to charge the system using liquid refrigerant.
d Either a lack or an excess of refrigerant causes the unit to make an
emergency stop. Charge the system with an appropriate amount of
refrigerant. When servicing, always check the notes concerning pipe
length and amount of additional refrigerant at both locations, the refrigerant
volume calculation table on the back of the service panel and the additional
refrigerant section on the labels for the combined number of indoor units
(Refer to item 9.2. for detailed information on refrigerant piping system).
Warning:
When installing and moving the unit, do not charge the system with any
other refrigerant other than the refrigerant specified on the unit.
- Mixing of a different refrigerant, air, etc. may cause the refrigerant cycle to
malfunction and may result in severe damage.
Caution:
• Use a vacuum pump with a reverse flow check valve.
- If the vacuum pump does not have a reverse flow check valve, the vacuum
pump oil may flow back into the refrigerant cycle and cause deterioration of
the refrigerant oil.
• Do not use the tools shown below used with conventional refrigerant.
(Gauge manifold, charge hose, gas leak detector, check valve,
refrigerant charge base, vacuum gauge, refrigerant recovery
equipment)
- Mixing of conventional refrigerant and refrigerant oil may cause the
refrigerant oil to deteriorate.
- Mixing of water will cause the refrigerant oil to deteriorate.
- R410A refrigerant does not contain any chlorine. Therefore, gas leak
detectors for conventional refrigerants will not react to it.
• Manage the tools used for R410A more carefully than normal.
- If dust, dirt, or water gets in the refrigerant cycle, the refrigerant oil will
deteriorate.
• Never use existing refrigerant piping.
- The large amount of chlorine in conventional refrigerant and refrigerant oil
in the existing piping will cause the new refrigerant to deteriorate.
• Store the piping to be used during installation indoors and keep both
ends of the piping sealed until just before brazing.
- If dust, dirt, or water gets into the refrigerant cycle, the oil will deteriorate
and the compressor may fail.
• Do not use a charging cylinder.
- Using a charging cylinder may cause the refrigerant to deteriorate.
• Do not use special detergents for washing piping.