Refrigerant Piping System; Additional Refrigerant Charge; Calculation Of Additional Refrigerant Charge; Precautions Concerning Piping Connection And Valve Operation - Mitsubishi Electric CITY MULTI PUHY-P850YSGM-A Manual De Instalación

9.2. Refrigerant piping system

Connection Example
[Fig. 9.2.1] (P.3)
Å Outdoor model
Ç Gas pipe
‰ Sub unit
Ì Total capacity of indoor units
¬ Downstream unit model total
The 1st branch
Ò 4-Branching header (Downstream unit model total
˜ 8-Branching header (Downstream unit model total
ˆ 10-Branching header (Downstream unit model total
A Outdoor unit
C Indoor unit
E Distributor (liquid), Distributor (gas) F To downstream units

10. Additional refrigerant charge

At the time of shipping, the outdoor unit is charged with the refrigerant. As this
charge does not include the amount needed for extended piping, additional charg-
ing for each refrigerant line will be required on site. In order that future servicing
may be properly provided, always keep a record of the size and length of each
refrigerant line and the amount of additional charge by writing it in the space pro-
vided on the outdoor unit.
10.1. Calculation of additional refrigerant
charge
• Calculate the amount of additional charge based on the length of the piping
extension and the size of the refrigerant line.
• Use the table to the below as a guide to calculating the amount of additional
charging and charge the system accordingly.
• If the calculation results in a fraction of less than 0.1 kg, round up to the next
0.1 kg. For example, if the result of the calculation was 28.92 kg, round the
result up to 29.0 kg.
<Additional Charge>
Additional Liquid pipe size
refrigerant charge Total length of
=
ø19.05 × 0.29
(m) × 0.29 (kg/m)
(kg)
Liquid pipe size
Total length of
+
ø9.52 × 0.06
(m) × 0.06 (kg/m)
<Example>
Indoor 1: P250 A: ø 15.88 3 m
2: P200 B: ø 15.88 1 m
3: P80 C: ø 19.05 40 m
4: P71 D: ø 15.88 10 m
5: P140 E: ø 12.7 5 m
6: P125 F: ø 9.52 5 m
7: P63 G: ø 12.7 30 m
8: P25 I : ø 9.52 5 m
J : ø 9.52 5 m
The total length of each liquid line is as follows:
ø19.05: C = 40 m
ø15.88: A + B + D = 14 m
ø12.7: E + G = 35 m
ø9.52: F + I + J + a + b + c + d + e + f + g = 70 m
ø6.35: i = 5 m
Therefore,
<Calculation example>
Additional refrigerant charge
= 40 × 0.29 + 14 × 0.2 + 35 × 0.12 + 70 × 0.06 + 5 × 0.024 + 6.0 = 29.0 kg
Value of α
Total capacity of connecting indoor units
Models 81 to 160
Models 161 to 330
Models 331 to 480
Models 481 to 630
Models 631 to 710
Models 711 to 890
Models 891 to 1070
Models 1071 to 1250
Models 1251 ~
12
ı Liquid pipe
Î Main unit
Ï Oil balance pipe
Ó Model number
Ô Branch kit model
< =
200)
< =
400)
< =
650)
B First branch
D Cap
Liquid pipe size Liquid pipe size
Total length of Total length of
+ +
ø15.88 × 0.2 ø12.7 × 0.12
(m) × 0.2 (kg/m) (m) × 0.12 (kg/m)
Liquid pipe size
Total length of
+ α
+
ø6.35 × 0.024
(m) × 0.024 (kg/m)
a : ø9.52 15 m
b : ø9.52 15 m
c : ø9.52 5 m
At the
d : ø9.52 5 m
conditions
e : ø9.52 5 m
below:
f : ø9.52 5 m
g : ø9.52 5 m
i : ø6.35 5 m
α
1.5 kg
2.0 kg
2.5 kg
3.0 kg
4.0 kg
5.0 kg
6.0 kg
7.0 kg
9.0 kg
G Oil balance pipe K
I Distributor (liquid) <accessory>
K Liquid line A
M Liquid line B
O Liquid line (main) C
Q Main unit
Note1:
• Downstream unit model total indicates the model total when the units
are viewed from C point in [Fig. 9.2.1].
Note2:
• The gas distributor is built in on the Sub unit, which means B is only the
liquid pipe.
Note3:
• Use CMY-Y302-G for the first branching. In this case, the downstream
unit model total capacity on each side must be 650 or less.
• When the down stream unit model total capacity on both sides exceeds
650, use 2 pieces of CMY-Y302-G, and branch them sequentially.
10.2. Precautions concerning piping connec-
tion and valve operation
• Conduct piping connection and valve operation accurately.
• The gas side connecting pipe and the distributor (gas) are assembled in fac-
tory before shipment.
1 When brazing the pipe and the connecting pipe with a flange/the distribu-
tor (gas) together, remove the connecting pipe with flange/the distributor
(gas) from the ball valve, and braze it outside of the unit.
2 During the time when removing the connecting pipe with flange/the dis-
tributor (gas), remove the seal attached on the rear side of this sheet and
paste it onto the flange surface of the ball valve to prevent the entry of dust
into the valve.
3 The refrigerant circuit is closed with a round, close-packed packing upon
shipment to prevent gas leak between flanges. As no operation can be
done under this state, be sure to replace the packing with the hollow pack-
ing attached at the piping connection.
4 At the mounting of the hollow packing, wipe off dust attached on the flange
sheet surface and the packing. Coat refrigerating machine oil (Ester oil,
ether oil or alkylbenzene [small amount]) onto both surfaces of the pack-
ing.
[Fig. 10.2.1] (P.4)
A Close-packed packing
B Hollow packing
• After evacuation and refrigerant charge, turn the handle and the oil balance
valve shaft to the OPEN position.
Operation of the unit with the closed valve will raise the pressure on the high-
pressure or low-pressure side in the refrigerant circuit, which may cause the
lack of oil flow between units and of oil in the compressor, leading to damage
to the compressor.
• Evacuate the oil balance pipe between the Main unit and the Sub unit.
After the oil balance pipe is connected, evacuate the pipe through the service
port by the oil balance stop valve. [Fig. 10.2.2 K] (P.4)
• 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 not to gener-
ate gas leak.
• Flare machining dimension for systems using R410A is larger than that for
systems using other types of refrigerant in order to increase the air tightness.
• Refer to the table on the below for flare machining dimensions, and follow the
regulations set forth by the local authorities. Seal off the opening of the pipe
with a closure material (not supplied) to keep small animals from entering the
pipe if that is a concern.
flare machining dimension (mm)
outer diameter
ø6.35
ø9.52
ø12.7
ø15.88
ø19.05
H Distributor (gas) <accessory>
J Gas line A
L Gas line B
N Gas line (main) C
P Indicates piping connection points
R Sub unit
dimension A
size in inches
R410A
1/4" 9.1
3/8" 13.2
1/2" 16.6
5/8" 19.7
3/4" 24.0