Design
D - 12
3. Refrigerant piping design
Ventilation quantity
Total quantity of refrigerant in refrigerant system (kg)
Room volume (m
3
)
In this region it is necessary to
provide an opening in the room for
effective ventilation thereby making
the room volume bigger,
or re-considering the capacity of
the outdoor unit or length of piping,
so as to reduce the total quantity
of refrigerant in the system.
In Figure 1, if 2/3>Total quantity of refrigerant in the system/room volume>0.3, then ventilation equipment providing the
indicated amount of ventilation is required.
The shaded region in Figure 1 is that region for which the total quantity of refrigerant in the system/room volume
2/3. In the
shaded region it is necessary to make the room bigger (by removing a door separating the room from the adjoining room for
example), or make the outdoor unit smaller.
For example, consider a 20 HP outdoor unit, and a 16.5m
‚Q
, 2.7mH room with one 1 HP indoor unit installed. After filling with
an additional 18kg of refrigerant the total quantity of refrigerant becomes 14.5 + 18 = 32.5 kg
32.5÷(16.5× 2.7)=0.73 > 2/3(=0.67)
This is in the shaded region of the graph, so it is necessary to make the room bigger or make the outdoor unit smaller (for
example, use 2 10 HP outdoor units).
* The outdoor unit is already charged with refrigerant at the time of shipping, so this must be added to the quantity of refrigerant
added on site.
[refer to (5) “Calculation of additional charge amount of refrigerant” for information on the quantity of refrigerant filled at the
time of shipping.
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