Caution For Piping Connection/Valve Operation - Mitsubishi Electric CITY MULTI PUMY-71 Manuel D'installation

Multi-distribution piping on outdoor unit
Connection Example
(Connecting up to Five Indoor Units)
* If multi-distribution piping on outdoor unit is done,
a maximum of 5 indoor units can be connected.
Permissible Total Piping Length
Length Farthest Piping Length
High/Low Difference in Indoor/Outdoor Section (H)
Permissible High/
High/Low Difference in Indoor/Indoor Section (h)
Low Difference
I Selecting Refrigerant Branch Kit
I Select Each Section of Refrigerant Piping
• Select the piping size for each section from
the branch to the indoor unit (a, b, c, d, e)
using the chart on the right.
I Additional refrigerant charge
• Refrigerant of 3 kg equivalent to 50-m total
extended piping length (model 125) or 2.4 kg
equivalent to 40-m (model 71) is already in-
cluded when the outdoor unit is shipped. Thus,
if the total extended piping length is 50 m or
less (model 125) or 40 m or less (model 71),
there is no need to charge with additional re-
frigerant.
• If the total extended piping length exceeds
50 m (model 125) or 40 m (model 71), calcu-
late the required additional refrigerant charge
using the procedure shown on the right.
• If the calculated additional refrigerant charge
is a negative amount, do not charge with any
refrigerant.

7.3. Caution for piping connection/valve operation

• Conduct piping connection and valve operation accurately by following the figure below.
• Apply sealer along the insulator to prevent water entering the insulator covering the refrigerant pipe joints.
• After evacuation and refrigerant charge, ensure that the handle is fully open. If operating with the valve closed, abnormal pressure will be imparted
to the high- or low-pressure side of the refrigerant circuit, giving damage to the compressor, four-way valve, etc.
• Determine the amount of additional refrigerant charge by using the formula, and charge refrigerant additionally through the service port after
completing piping connection work.
• After completing work, tighten the service port and cap securely to prevent gas leak.
A
B
Cannot redistribute the piping.
a + b + c + d + e is 100 meters or less (125 Type), 80 meters or less (71 Type)
(L) e is 30 meters or less
30 meters or less (20 meters or less if the outdoor unit is below.)
12 meters or less
Use multi-distribution piping on outdoor unit kit CMY-S65 (5 branches).
* Cannot be connected with 100, 125 type indoor units.
• Refrigerant Piping Diameter in Section From Branch to Indoor Unit
(Indoor Unit Piping Diameter)
Model Piping Diameter (mm)
Liquid Line
40 or lower
Gas Line
Liquid Line
50 to 80
Gas Line
Additional Liquid pipe size
refrigerant charge Total length of
ø9.52 × 0.06
=
(m) × 0.06 (kg/m)
(kg)
<Example>
Outdoor Unit : 125 Type
Indoor 1 : 20 a : ø6.35. . . 10 m
2 : 20 b : ø6.35. . . 20 m
3 : 20 c : ø6.35. . . 20 m
4 : 50 d : ø9.52. . . 20 m
5 : 50 e : ø9.52. . . 30 m
The total length of each liquid line is as follows
ø9.52: d + e = 20 + 30 = 50 m
ø6.35: a + b + c = 10 + 20 +20 = 50 m
Therefore:
Additional refrigerant charge = 50 × 0.06 + 50 × 0.024 – 3.0 = 1.2 kg (rounded up)
L
a b c d e
C C
1 2
C C
3 4
C
5
ø6.35
ø12.7
ø9.52
ø15.88
Liquid pipe size
Total length of
ø6.35 × 0.024
+
(m) × 0.024 (kg/m)
A Outdoor unit
B First branch
C Indoor unit
Refrigerant
amount for outdoor
unit
–
71: 2.4 kg
125: 3.0 kg
11