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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
× ceiling height 2.7 m = room volume 40.5 m
2
at right shows that the maximum overall refrigerant charge
amount of limit density (0.44 kg/m
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
) × 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
= 82.05 (m
)
3
Required minimum floor area
= (minimum room volume) ÷ (ceiling height)
= 82.05 (m
) ÷ 2.7 (m)
3
= 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
36.103 (kg)
=
40.5 (m³)
= 0.89 (kg/m
) > 0.44 (kg/m³)
3
Accordingly, it is necessary to install a ventilation fan for this
room.
), the graph
3
) that is not required to install
3
)
3
)
3
2
3
m
m
85
229.5
80
216.0
75
202.5
70
189.0
65
175.5
60
162.0
55
148.5
50
135.0
45
121.5
40
108.0
35
94.5
30
81.0
25
67.5
20
54.0
15
40.5
10
27.0
5
13.5
0
0.0
)
3
20
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)
0
10
20
30
40
50
Total amount of refrigerant
60
70
80
90 100
kg
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