20
CAUTION
Be sure to check the limit density for the room in which the indoor unit is installed.
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
15 m
2
× ceiling height 2.7 m = room volume 40.5 m
3
), the graph
at right shows that the maximum overall refrigerant charge
amount of limit density (0.44
kg
/m
3
) that is not required to install
a ventilation fan should be calculated as follows.
Due to the room volume,
Maximum overall refrigerant charge amount
= (room volume) × (limit density)
= 40.5 (m
3
) × 0.44 (
kg
/m
3
)
= 17.82
kg
Overall refrigerant charge amount for this system is 36.103 (
kg
).
The formula for the minimum room volume should be
determined as follows.
Required minimum room volume
= (overall refrigerant charge amount) ÷ (limit density)
= 36.103 (
kg
) ÷ 0.44 (
kg
/m
3
)
= 82.05 (m
3
)
Required minimum floor area
= (minimum room volume) ÷ (ceiling height)
= 82.05 (m
3
) ÷ 2.7 (m)
= 30.4 (m
2
)
Therefore an opening for ventilation is required.
< Formula for computation >
Overall refrigerant charge amount for the air conditioner:
kg
(Minimum room volume for indoor unit: m
3
)
=
36.103 (
kg
)
40.5 (m³)
= 0.89 (
kg
/m
3
) >
0.44 (
kg
/m³)
Accordingly, it is necessary to install a ventilation fan for this
room.
20
10
0
30
40
60
70
80
90 100
50
m
2
m
3
40.5
54.0
27.0
13.5
0.0
67.5
81.0
94.5
108.0
121.5
135.0
148.5
162.0
175.5
189.0
202.5
216.0
15
10
5
0
20
25
30
35
40
45
50
55
60
65
70
75
80
229.5
85
kg
Total amount of refrigerant
Range below the
density limit of
0.44
kg
/m³
(Countermeasures
not needed)
Range above the
density limit of
0.44
kg
/m³
(Countermeasures
needed)
Min. indoor volume
Min. indoor floor area (when the ceiling is 2.7 m high)
00_341136_2WAY_Eng.indb 20
2022/9/19 9:27:18
