Mitsubishi Electric CITY MULTI PUMY-71 Manuel D'installation page 9

Header-Branch Method
Connection Examples
(Connecting to Four Indoor Units)
Total Piping Length
Permissible
Farthest Piping Length
Length
Farthest Piping Length After First Branch (r)
High/Low Difference in Indoor/Outdoor Section (H)
Permissible High/
Low Difference High/Low Difference in Indoor/Indoor Section (h)
I Selecting the Refrigerant Branch Kit
I Select Each Section of Refrigerant Piping
(1) Section From Outdoor Unit
to First Branch (A)
(2) Sections From Branch to
Indoor Unit (a, b, c, d)
Select the size from the table to 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.
A
A
a
C
1
A+a+b+c+d is 100 meters or less (125 Type), 80 meters or less (71 Type)
(L) A+d is 70 meters or less (125 Type), 50 meters (71 Type)
d is 30 meters or less
30 meters or less (If the outdoor unit is lower, 20 meters or less)
12 meters or less
Please select branching kit, which is sold separately, from the table below.
(The kit comprises sets for use with liquid pipes and for use with gas pipes.)
Branch header (4 branches)
CMY-Y64-C
(1) Refrigerant Piping Diameter In Section
From Outdoor Unit to First Branch (Out-
door Unit Piping Diameter)
Each
Model
Section of
Piping
PUMY-71
PUMY-125
<Additional Charge>
Additional
refrigerant charge
(kg)
<Example>
Outdoor model : 125
Indoor 1 : 50
2 : 40
3 : 25
4 : 20
The total length of each liquid line is as follows
ø9.52 : A + a = 30 + 15 = 45 m
ø6.35 : b + c + d = 10 + 10 + 20 = 40 m
Therefore,
<Calculation example>
Additional
refrigerant charge = 45 × 0.06 + 40 × 0.024 – 3.0 = 0.7 kg (rounded up)
L
B
R
b c
C
C
2
3
Branch header (8 branches)
CMY-Y68
Piping Diameter (mm)
Liquid Line ø9.52
Gas Line ø15.88
Liquid Line ø9.52
Gas Line ø19.05
Liquid pipe size Liquid pipe size
Total length of Total length of
ø9.52 × 0.06 ø6.35 × 0.024
= +
(m) × 0.06 (kg/m) (m) × 0.024 (kg/m)
A : ø9.52 30 m a : ø9.52
b : ø6.35
c : ø6.35
d : ø6.35
d
C
A Outdoor Unit
4
B First Branch
C Indoor unit
* The CMY-Y68 cannot be
connected with 100, 125
type indoor units.
(2) Refrigerant Piping Diameter In Section
From Branch to Indoor Unit (Indoor Unit
Piping Diameter)
Model number Piping dia. (mm)
Liquid Line
40 or lower
Gas Line
Liquid Line
50 to 80
Gas Line
Liquid Line
100, 125
Gas Line
Refrigerant
amount for outdoor
unit
–
71: 2.4 kg
125: 3.0 kg
15 m
At the conditions
10 m
below:
10 m
20 m
ø6.35
ø12.7
ø9.52
ø15.88
ø9.52
ø19.05
9