Refrigerant Piping Installation; Areas Of Caution - Mitsubishi Electric CITY MULTI PUHY-YSMF-B Installationshandbuch

10. Refrigerant piping installation

Connecting the piping is a terminal-branch type in which refrigerant piping from the outdoor unit is branched at the terminal and connected to each of
the indoor units.
The method of connection consists of flare connections at the indoor units, flange connections for the piping of the outdoor unit and flare connections
for the liquid, oil balance piping. Note that the branched sections are brazed.
Warning:
Always use extreme care to prevent the refrigerant gas (R22) from leaking while using fire or flame. If the refrigerant gas comes in contact
with the 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.

10.1. Areas of caution

1 Use the following materials for refrigeration piping.
• Material: Seamless phosphorous deoxidized copper pipe, C1220T-OL or C1220T-O (Note: C1220T-OL is preferred.)
Size: Refer to pages 13 to 14 .
•
2 Commercially available piping often contains dust and other materials. Always blow it clean with a dry inert gas.
3 Use care to prevent dust, water or other contaminants from entering the piping during installation.
4 Reduce the number of bending portions as much as possible, and make bending radius as big as possible.
5 Always use the branch piping set shown below, which are sold separately. This unit requires a CMC-30A (optional).
Total of units down- Total of units down-
stream less than 160 stream 161 to 330
CMY-Y102S-F CMY-Y102L-F
6 If the diameters of the branch piping of the designated refrigerant piping differs, use a pipe cutter to cut the connecting section and then use an
adapter for connecting different diameters to connect the piping.
7 Always observe the restrictions on the refrigerant piping (such as rated length, the difference between high/low pressures, and piping diameter).
Failure to do so can result in equipment failure or a decline in heating/cooling performance.
8 A second branch cannot be made after a header branch. (These are shown by
A
A To outdoor unit
B Capped piping
9 Always use good-quality materials for brazing.
0 The City Multi Series Super Y will stop due an abnormality due to excessive or insufficient coolant. At such a time, always properly charge the unit.
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 pages 13 to 14 .)
A Never perform a pump down. This will damage the compressor.
B Never use refrigerant to perform an air purge. Always evacuate using a vacuum pump.
C Always insulate the piping properly. Insufficient insulation will result in a decline in heating/cooling performance, water drops from condensation and
other such problems. (Refer to pages 22 to 23 .)
D When connecting the refrigerant piping, make sure the ball valve of the outdoor unit is completely closed (the factory setting) and do not operate it
until the refrigerant piping for the outdoor and indoor units has been connected, a refrigerant leakage test has been performed and the evacuation
process has been completed.
E Always use a non-oxidizing brazing material for brazing the parts. If a non-oxidizing brazing material is not used, it could cause clogging or damage
to the compressor unit. (Details of the piping connections and valve operation can be found on pages 15 to 19 .)
Warning:
When installing and moving the air conditioner to another site, do not charge the it with a refrigerant different from the refrigerant (R22)
specified on the unit.
- If a different refrigerant or air is mixed with the original refrigerant, the refrigerant cycle may malfunction and the unit may be damaged.
12
Branch pipe set name
Line branching
Total of units down-
stream 331 to 630
CMY-Y202-F
Total of units down-
4 branching
stream more than 631
CMY-Y302-F CMY-Y104-E
×
.)
A
Header branching
7 branching 10 branching
CMY-Y107-E CMY-Y1010-E
B