10
Check of Density Limit
Check the amount of refrigerant in the system and floor space of the room according to the 
legislation on refrigerant drainage. If there is no applicable legislation, follow the standards 
described below.
The refrigerant (R32), which is used in the air conditioner, is a flammable refrigerant. So the 
requirements for the maximum refrigerant charge amount [m
max
] used in the appliance are 
determined according to installation space of the appliance.
Installation conditions  
Procedure of preliminary calculation
1.  Determine the room space in accordance with the requirements of installation.
2.  Calculate the maximum refrigerant charge amount [m
max
]. 
When connecting the refrigerant tubes and installing the 
indoor unit in each partitioned room, it is necessary to 
calculate the allowable refrigerant charge amount in each 
room.
For all indoor units shown in Fig. 1, calculate the 
allowable refrigerant charge amount that can be used in 
each room [m
IN_1
, m
IN_2
,---, m
IN_n
]. 
Calculate the maximum refrigerant charge for each indoor 
unit from Fig. 2 by referring to the following items.
- Floor area of the room
- Indoor units type
- Capacity of indoor unit
- Installation height of Indoor Unit
- Use or nonuse of R32 refrigerant leakage detection sensor
Room No.
No. of 
indoor 
units
Indoor units type
Capacity 
of indoor 
unit
Installation 
height of 
Indoor Unit: 
h
inst
 (m)
R32 refrigerant 
leakage detection 
sensor
Floor area 
of the 
room (m
2
)
Refrigerant charge 
amount that can 
be used for each 
indoor unit (k
g
)
Room_1 IN_1 4-Way Cassette 60 × 60 15 h
inst
 
≥
 2.2 Use 10 m
IN_1
Room_2 IN_2 Slim Low Static Ducted 56 h
inst
 
≥
 2.2 Nonuse 15 m
IN_2
Room_3 IN_3 4-Way Cassette 56 h
inst
 
≥
 2.2 Use 20 m
IN_3
--- --- --- --- --- --- --- ---
Room_m IN_n-1 Wall-Mounted 45 h
inst
 
≥
 1.8 Nonuse 30 m
IN_n-1
Room_m IN_n 4-Way Cassette 140 h
inst
 
≥
 2.2 Use 30 m
IN_n
[m
max
] = Min (m
IN_1
, m
IN_2
, m
IN_3
, ---, m
IN_n-1
, m
IN_n
) 
The minimum value of the allowable refrigerant charge amount in each room is the maximum 
value of the maximum refrigerant charge amount [m
max
] that can be used in the system.
3.  Calculate the maximum refrigerant charge amount [m
c
] by following details of piping 
installation. 
As a reference, refer to Installation Instructions of outdoor unit.
4.  Determine from two values [m
max
] in Step 2 and [m
c
] in Step 3.
[m
c
] 
≤
 [m
max
] : Can be installed.
[m
c
] > [m
max
] :  Return to Steps 1 to 3 and change the indoor unit type, capacity and pipe 
length.
IN_1
Room_1 Room_2 Room_3 Room_m
IN_2
IN_3 IN_n
IN_n-1
Fig. 1
01_330200_EU_Eng.indb   10 2021/1/13   10:22:56