Mitsubishi Electric MXZ-8B48NA Manuel D'installation page 7

5. Installing the refrigerant piping
5.3. Addition of refrigerant
• Additional charging is not necessary for this unit if the total pipe length
(b1+b2+a1+a2+a3+a4+a5+a6+a7+a8) does not exceed 40 m (131 ft.).
• If the total pipe length exceeds 40 m (131 ft.), charge the unit with
additional R410A refrigerant according to the permitted pipe lengths in
the chart below.
* When the unit is stopped, charge the unit with the additional refrigerant through
the liquid stop valve after the pipe extensions and indoor unit have been vacu-
umized.
When the unit is operating, add refrigerant to the gas check valve using a safe-
ty charger. Do not add liquid refrigerant directly to the check valve.
* After charging the unit with refrigerant, note the added refrigerant
amount on the service label (attached to the unit).
Refer to the "1.5. Using R410A refrigerant air conditioners" for more information.
Table 1
Total piping length
(b1+b2+a1+a2+a3+a4+a5+a6+a7+a8)
Additional refrigerant charging amount
In case of using 1-branch box
Flare connection employed. (No. brazing)
A
B
In case of using 2-branch boxes
2 branches pipe (joint)
: optional parts.
A A
A
B B
Fig. 5-2
(1) Valve size for outdoor unit
For liquid
For gas
(2) Valve size for branch box
Liquid pipe
A UNIT
Gas pipe
Liquid pipe
B UNIT
Gas pipe
Liquid pipe
C UNIT
Gas pipe
Liquid pipe
D UNIT
Gas pipe
Liquid pipe
E UNIT
Gas pipe
* 3-branch type : only A, B, C unit
A
Fig. 5-3
41 - 50 m 51 - 70 m 71 - 90 m 91 - 115 m
(135 - 164 ft.) (165 -230 ft.) (231 - 295 ft.) (296 - 377 ft.)
0.6 kg 1.4 kg 2.2 kg 3.2 kg
(21 oz) (49 oz) (78 oz) (113 oz)
Branch box
B B B
Branch box #1
B B
Branch box #2
ø9.52 mm (3/8 inch)
ø15.88 mm (5/8 inch)
ø6.35 mm (1/4 inch)
ø9.52 mm (3/8 inch)
ø6.35 mm (1/4 inch)
ø9.52 mm (3/8 inch)
ø6.35 mm (1/4 inch)
ø9.52 mm (3/8 inch)
ø6.35 mm (1/4 inch)
ø9.52 mm (3/8 inch)
ø6.35 mm (1/4 inch)
ø12.7 mm (1/2 inch)
Conversion formula
1/4 F ø6.35 (1/4)
3/8 F ø9.52 (3/8)
1/2 F ø12.7 (1/2)
5/8 F ø15.88 (5/8)
B
3/4 F ø19.05 (3/4)
If connecting an indoor unit with ø9.52 mm (3/8 inch) liquid pipes (model number
24 or more for M- and S-Series and model number 18 or more for P-Series), the
additional refrigerant charging amount in Table 1 must be corrected (add the follow-
ing ΔR value from the value given in Table 1).
Additional refrigerant charging correction amount
ΔR = 0.01 [kg/m] × ø9.52 (3/8 inch) branch pipe (liquid pipe) total length [m]
(0.107 [oz/ft] × ø9.52 (3/8 inch) branch pipe (liquid pipe) total length [ft])
Example) b1 = 20 m (66 ft.), b2 = 25 m (82 ft.)
Indoor unit A
Indoor unit B
Indoor unit C
Indoor unit D
Total piping length : b1+b2+a1+a2+a6+a7=95 m (312 ft.)
→ According to Table 1, the additional refrigerant charging amount is 3.2 kg (113 oz).
Because indoor units with ø9.52 (3/8) liquid pipes are connected (indoor units A and
D in this example), the additional refrigerant charging amount must be corrected.
Additional refrigerant charging correction amount
ΔR = 0.01 [kg/m] × ø9.52 (3/8) branch pipe (liquid pipe) total length (a1+a7)
= 0.01 × (12+13 m) [0.107 ×(39+43 ft.)]
= 0.25 kg (9 oz)
Therefore, the additional refrigerant charging amount is
3.2 kg + 0.25 kg = 3.45 kg [113 oz + 9 oz =122 oz].
5.4. Selecting pipe size (Fig. 5-2)
Conversion formula
A
ø9.52 mm
Liquid
(3/8 inch)
B
ø15.88 mm
Gas
(5/8 inch)
Different-diameter joint (optional parts) (Fig. 5-3)
Connected pipes diameter
Model name
MAC-A454JP ø9.52 (3/8) → ø12.7 (1/2)
MAC-A455JP ø12.7 (1/2) → ø9.52 (3/8)
MAC-A456JP ø12.7 (1/2) → ø15.88 (5/8)
PAC-493PI ø6.35 (1/4) → ø9.52 (3/8)
B
PAC-SG76RJ-E ø9.52 (3/8) → ø15.88 (5/8)
Piping preparation
1 Table below shows the specifi cations of pipes commercially available.
Outside diameter Insulation thickness
mm (inch)
6.35 (1/4)
9.52 (3/8)
12.7 (1/2)
15.88 (5/8)
2 Ensure that the 2 refrigerant pipes are insulated to prevent condensation.
3 Refrigerant pipe bending radius must be 4" (100 mm) or more.
Caution
Be sure to use the insulation of specifi ed thickness. Excessive thickness
may cause incorrect installation of the indoor unit and branch box, and
lack of thickness may cause dew drippage.
2-branch pipe (Joint) : Optional parts (According to the connection method,
you can choose the favorite one.
Model name
MSDD-50AR-E
MSDD-50BR-E
■
Installation procedure (2 branches pipe (Joint))
Refer to the installation manuals of MSDD-50AR-E and MSDD-50BR-E.
ø9.52 (3/8) Liquid pipe
ø6.35 (1/4) Liquid pipe
ø6.35 (1/4) Liquid pipe
ø9.52 (3/8) Liquid pipe
B
The piping connection size differs ac-
cording to the type and capacity of indoor
units. Match the piping connection size of
branch box with indoor unit.
If the piping connection size of branch
box does not match the piping connection
size of indoor unit, use optional different-
diameter (deformed) joints to the branch
box side. (Connect deformed joint directly
to the branch box side.)
Diameter A
mm (inch) mm (inch)
ø9.52 (3/8)
ø12.7 (1/2)
ø12.7 (1/2)
ø6.35 (1/4)
ø9.52 (3/8)
Insulation material
mm (inch)
8 (5/16)
8 (5/16)
Heat resisting foam plastic 0.045
specifi c gravity
8 (5/16)
8 (5/16)
Connection method
fl are
brazing
a1=12 m (39 ft.)
a2=11 m (36 ft.)
a6=14 m (46 ft.)
a7=13 m (43 ft.)
Diameter B
mm (inch)
ø12.7 (1/2)
ø9.52 (3/8)
ø15.88 (5/8)
ø9.52 (3/8)
ø15.88 (5/8)
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