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Vacuum drying
Be sure to perform vacuuming from both liquid and gas sides.
Be sure to use a vacuum pump equipped with the counter-flow prevention function so that oil in the pump will
not flow back into piping for air conditioners. (If oil in the vacuum pump enters in the air conditioner with R410A
refrigerant, a problem may be caused in the refrigerating cycle.)
After finishing the airtight test and discharging nitrogen gas, connect the gauge manifold to the service ports of the
liquid side and gas side and connect a vacuum pump as shown in the figure below. Be sure to perform vacuuming
for the liquid and gas pipe sides.
Connected to indoor unit
Main piping
Valve details
To gauge
manifold
To outdoor unit
Liquid-side
Liquid-side
valve
Gas-side valve
service port
To
outdoor
unit
Gas-side
Piping at site
service port
Piping at site
Follower units
Use a vacuum pump with a high vacuuming degree [-100.7 kPa (5 Torr, -755 mmHg)] and large exhaust gas
amount (40 L/minute or larger).
Perform vacuuming for 2 or 3 hours, though the time differs depending on the pipe length. Check that all the
packed valves at the liquid side and gas side are fully closed.
If the pressure does not reach -100.7 kPa or less, continue vacuuming for 1 hour or more. If the pressure does
not reach -100.7 kPa after 3 hours of vacuuming, stop vacuuming and check for air leakage.
If the pressure reaches -100.7 kPa or less after vacuuming for 2 hours or more, close the valves VL and VH on
the gauge manifold fully and stop the vacuum pump. Leave it as it is for 1 hour to confirm that the vacuuming
degree does not change.
If the degree of vacuum loss is large, moisture may remain in the pipes. In that case, inject dry nitrogen gas and
apply pressure to 0.05 MPa and perform vacuuming again.
After finishing the above procedure of vacuuming, exchange the vacuum pump with a refrigerant canister and
advance to the additional charging of refrigerant.
Low pressure
High pressure
gauge
gauge
Ball valve fully closed
(gas side)
Gauge
V
V
L
H
Header outdoor unit
manifold
Service port
Brazed
Brazed
Service port
P
Packed valve fully closed
Vacuum pump
(liquid side)
Adding refrigerant
After finishing vacuuming, exchange the vacuum pump with a refrigerant canister and start additional charging of
refrigerant.
Calculation of additional refrigerant charge amount
Refrigerant charge amount at shipment from the factory does not include the refrigerant for pipes at the local site.
For refrigerant to be charged in pipes at the local site, calculate the amount and charge it additionally.
NOTE
If the additional refrigerant amount indicates minus as the result of calculation, use the air conditioner without
additional refrigerant.
38VT0081 38VT0101 38VT0121 38VT0141 38VT014A 38VT0161 38VT0181 38VT0201 38VT0221 38VT0241 38VT0261
Outdoor unit type
Charging amount (kg)
6.0
Additional refrigerant charge amount at site = [1] + [2] + [3]
[1] Compensation by system HP (Table 1)*
[2] Real Length of liquid pipe X additional refrigerant charge amount per 1 m liquid pipe (Table 2)
[3] Corrective amount of refrigerant depending on the Indoor units (Table 3-1, 3-2, 3-3 and 3-4)
* If combination of the outdoor units is not same as listed at Table 1,calculate the correction amount refrigerant
of the combination outdoor units refers to the each outdoor unit's additional refrigerant
Table 1
Standard
System HP
Combionation HP
8
8
-
10
10
-
12
12
-
14
14
-
14A
14A
-
16
16
-
18
18
-
20
20
-
22
22
-
24
24
-
26
26
-
28
14
14
30
18
12
32
20
12
34
22
12
36
24
12
38
26
12
40
26
14
42
22
20
44
22
22
46
24
22
48
24
24
– 20 –
9.0
Conpensation by System HP (kg)
-
-
-
-0.3
-
-
-
-0.3
-
-
-
-0.3
-
-
-
-0.3
-
-
-
-1.0
-
-
-
-1.0
-
-
-
-1.0
-
-
-
-1.0
-
-
-
1.5
-
-
-
1.5
-
-
-
1.5
-
-
-
-0.6
-
-
-
-1.3
-
-
-
-1.3
-
-
-
1.2
-
-
-
1.2
-
-
-
1.2
-
-
-
1.2
-
-
-
0.5
-
-
-
3.0
-
-
-
3.0
-
-
-
3.0
EN
EN
EN
ID
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