Panasonic U-4LE1E5 / U-4LE1E8 / U-5LE1E5 / U-5LE1E8 / U-6LE1E5 / U-6LE1E8 (serv.man2) Service Manual ▷ View online
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Design of Mini VRF SYSTEM
2. System Design
2-2. Example of Tubing Size Selection and Refrigerant Charge Amount
Additional refrigerant charging
Based on the values in Tables 1-2, 1-3, 1-4 and 1-7, use the liquid tubing size and length, and calculate the amount
of additional refrigerant charge using the formula below.
Neccessary additional refrigerant charge (k
g) = [56 × (a) + 26 × (b)] × 10
–3
(a): Liquid tubing
Total length of ø9.52 (m)
(b): Liquid tubing
Total length of ø6.35 (m)
Charging procedure
Be sure to charge with R410A refrigerant in liquid form.
1.
in the “fully closed” position.
2.
After performing a vacuum, charge with refrigerant from the liquid tubing side. At this time, all valves must be
If it was not possible to charge the designated amount, operate the system in Cooling mode while charging
with refrigerant from the gas tubing side. (This is performed at the time of the test run. For this, all valves
must be in the “fully open” position.)
Charge with R410A refrigerant in liquid form.
With R410A refrigerant, charge while adjusting the amount being fed a little at a time in order to prevent
liquid refrigerant from backing up.
After charging is completed, turn all valves to the “fully open” position.
Replace the tubing covers as they were before.
Replace the tubing covers as they were before.
CAUTION
1
3
4
2
Tightening torque for
valve stem cap:
19 – 21 N·m
valve stem cap:
19 – 21 N·m
Tightening torque:
34 – 42 N·m
34 – 42 N·m
Tightening torque:
68 – 82 N·m
68 – 82 N·m
Tightening torque for valve
stem cap: 28 – 32 N·m
stem cap: 28 – 32 N·m
1. R410A additional charging absolutely must be done through liquid charging.
2. The R410A refrigerant cylinder has a gray base color, and the top part is pink.
3. The R410A refrigerant cylinder includes a siphon tube. Check that the siphon
tube is present. (This is indicated on the label at the top of the cylinder.)
4. Due to differences in the refrigerant, pressure, and refrigerant oil involved in
installation, it is not possible in some cases to use the same tools for R22 and
for R410A.
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Design of Mini VRF SYSTEM
2. System Design
Checking of limit density
Density limit is determined on the basis of the size of
a room using an indoor unit of minimum capacity.
For instance, when an indoor unit is used in a room
(floor area 7.43 m
2
× ceiling height 2.7 m = room
volume 20.06 m
3
), the minimum room volume should
be 25.8 m
3
(7.738 k
g ÷ 0.3 kg/m
3
) for refrigerant of
7.738 k
g (3.5 kg + 4.238 kg).
Accordingly, openings such as louvers are required
for this room.
<Determination by calculation>
Overall refrigerant charge amount for the air conditioner: k
g
(Minimum room volume for indoor unit: m
3
)
=
4.238 (k
g) + 3.5 (kg)
= 0.39 (k
g/m
3
) > 0.3 (k
g/m
3
)
20.06 (m
3
)
Therefore, openings such as louvers are required for
this room.
this room.
Be sure to check the limit density
for the room in which the indoor
unit is installed.
CAUTION
Example:
LN
L1
L2
L2
LC
LB
LA
1
2
3
n–1
n
Example of each tubing length
Main tubing
Distribution joint tubing
LA = 40 m
Indoor side
LB = 5 m
1
= 5 m
4
= 6 m
LC = 5 m
2
= 5 m
5
= 5 m
LD = 15 m
3
= 2 m
Obtain charge amount for each tubing size
Note that the charge amounts per 1 meter are different for each liquid tubing size.
ø9.52
→ LA + LB + LC + LD
: 65 m
× 0.056 kg/m = 3.64 kg
ø6.35
→
1
+
2
+
3
+
4
+
5
: 23 m
× 0.026 kg/m = 0.598 kg
Additional refrigerant charge amount is 4.238 k
g.
Main tube of unit
1st branch
Unit distribution tube
Type 56
Type 22
Type 28
Type 36
Type 45
4.238 k
g
Total
40.5
54.0
27.0
13.5
13.5
0.0
20
10
0
30
40
60
70
80
90 100
50
67.5
81.0
94.5
108.0
121.5
135.0
148.5
162.0
175.5
189.0
202.5
216.0
229.5
243.0
256.0
270.0
m
2
m
3
15
10
10
5
0
0
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
283.5
297.0
310.5
324.0
337.5
k
g
Range below the
density limit of
0.3 k
density limit of
0.3 k
g/m³
(Countermeasures
not needed)
not needed)
Range above the
density limit of 0.3
k
density limit of 0.3
k
g/m³
(Countermeasures
needed)
needed)
Total amount of refrigerant
Min. indoor volume
Min. indoor floor area
(when the ceiling is 2.7 m high)
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Design of Mini VRF SYSTEM
2. System Design
2-3. Installing Distribution Joint
(1) Refer to “HOW TO ATTACH DISTRIBUTION
JOINT” enclosed with the optional distribution
joint kit (CZ-P160BK2).
(2) In order to prevent accumulation of refrigerant oil in
stopped units, if the main tubing is horizontal then
each branch tubing length should be at an angle
that is greater than horizontal. If the main tubing is
vertical, provide a raised starting portion for each
branch.
(3) If there are height differences between indoor units
or if branch tubing that follows a distribution joint
is connected to only 1 unit, a trap or ball valve (field
supply) must be added to that distribution joint.
(When adding the ball valve (field supply), locate it
within 40 cm of the distribution joint.)
If a trap or ball valve (field supply) is not added,
do not operate the system before repairs to a
malfunctioning unit are completed.
(The refrigerant oil sent through the tubing to
the malfunctioning unit will accumulate and may
damage the compressor.)
Tube branching methods (horizontal use)
Types of vertical trap specifications
(When using ball valve (field supply))
Main tubing
Indoor unit (more than 2 units)
(If only 1 unit is connected, a ball
valve is also needed on this side.)
valve is also needed on this side.)
Ball valve
(BV: field supply)
Indoor unit (1)
(When not using ball valve)
Main tubing
Horizontal
Indoor unit
Indoor unit
Branch tubing is
directed upward.
directed upward.
More than
20 cm
20 cm
(Each unit is
connected to tubing
that is either level or is
directed downward.)
connected to tubing
that is either level or is
directed downward.)
Indoor unit is directed downward
B
A
B
A
A
B
15 to 30
°
Horizontal
line
line
View as seen
from arrow
from arrow
15 to 30°
Arrow view D
Arrow view C
view D
view C
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Design of Mini VRF SYSTEM
3. Electrical Wiring
3-1. General Precautions on Wiring
3-2. Recommended Wire Length and Wire Diameter for Power Supply System
(1) Before wiring, confirm the rated voltage of the unit as shown
on its nameplate, then carry out the wiring closely following
the wiring diagram.
(2) Provide a power outlet to be used exclusively for each
unit, and a power supply disconnect, circuit breaker and
earth leakage breaker for overcurrent protection should be
provided in the exclusive line.
(3) To prevent possible hazards from insulation failure, the unit
must be grounded.
(4) Each wiring connection must be done in accordance with the
wiring system diagram. Wrong wiring may cause the unit to
disordor or become damaged.
(5) Do not allow wiring to touch the refrigerant tubing,
compressor, or any moving parts of the fan.
(6) Unauthorized changes in the internal wiring can be very
dangerous. The manufacturer will accept no responsibility
for any damage or misoperation that occurs as a result of
such unauthorized changes.
(7) Regulations on wire diameters differ from locality to
locality. For field wiring rules, please refer to your LOCAL
ELECTRICAL CODES before beginning.
You must ensure that installation complies with all
relevant rules and regulations.
relevant rules and regulations.
(8) To prevent malfunction of the air conditioner caused by
electrical noise, care must be taken when wiring as follows:
The remote control wiring and the inter-unit control wiring
should be wired apart from the inter-unit power wiring.
Use shielded wires for inter-unit control wiring between units
and ground the shield on both sides.
(9) If the power supply cord of this appliance is damaged,
it must be replaced by a repair shop appointed by the
manufacturer, because special purpose tools are required.
Outdoor unit
(Single-phase)
(A) Power supply
Time delay capacity
Fuse
Circuit breaker
Fuse
Circuit breaker
U-4LE1E5
U-5LE1E5
U-6LE1E5
6 mm²
4 mm²
6 mm²
21 m
24 m
20 m
25 A
35 A
35 A
30 A
40 A
40 A
(3-phase)
(A) Power supply
Time delay capacity
Wire size
Max. length
Wire size
Max. length
U-4LE1E8
U-5LE1E8
U-6LE1E8
2.5 mm²
2.5 mm²
2.5 mm²
58 m
49 m
41 m
20 A
20 A
20 A
20 A
20 A
20 A
Control wiring
(C) Inter-unit (between outdoor and
indoor units) control wiring
indoor units) control wiring
0.75 mm² (AWG #18)
Use shielded wiring*
(D) Remote control wiring
0.75 mm² (AWG #18)
Max. 500 m
N OT E
* With ring-type wire terminal.
(E) Control wiring for group control
0.75 mm² (AWG #18)
Max. 200 m (Total)
Max. 1,000 m
Indoor unit
Type
(B) Power supply
Time delay fuse or
circuit capacity
2.5 mm²
Minimum 2 mm²
Max. 150 m
Max. 130 m
Max. 150 m
Max. 130 m
Max. 60 m
10 – 16 A
15 A
15 A
K1
K2
Y2
D1, L1, U1, Y1, T1,
F1, M1, P1, R1
E1 (73, 106, 140)
10 – 16 A
10 – 16 A
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