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15.1 Calculating Additional
Refrigerant Charge
The additional refrigerant charge required depends on the
lengths and diameters of the outdoor and indoor liquid
pipes and the capacity of the IDU connected. Tables 15-1 to
15-3 show the additional refrigerant charge required under
different conditions.
Additional refrigerant charge R1 (according to liquid pipe
lengths and diameters)
Table 15-1
Diameter of
liquid pipe
(mm OD)
Additional refrigerant charge
(Equivalent length of liquid pipe per meter)
(kg)
Φ6.35
0.019
Φ9.52
0.049
Φ12.7
0.096
Φ15.9
0.153
Additional refrigerant charge (R1) is the sum of additional
charges of each outdoor and indoor liquid pipe, as shown
in the following formula, where L1 to L4 represent the
equivalent length of pipes with different diameters.
Additional refrigerant charge R1 (kg) = L1 (Φ6.35) × 0.019 +
L2 (Φ9.52) × 0.049 + L3 (Φ12.7) × 0.096 + L4 (Φ15.9) × 0.153
Additional refrigerant charge R2(Determined by the capacity
of VRF IDU connected)
Table 15-2
Capacity of IDU
connected
(× 1000W)
Additional refrigerant charge per
1000W capacity
(kg)
A
0.0238
Additional refrigerant charge R2 = A × 0.0238
Additional refrigerant charge R3(Determined by whether a
DHW kit or hydraulic module is connected)
Table 15-3
ODU model
(kW)
With DHW kit
With
hydraulic
module
Additional
refrigerant
charge (kg)
8
No
Yes
0
10
No
Yes
0
12
No
Yes
0
Yes
No
0
14
No
Yes
0.333
16
No
Yes
0.380
Table 15-4
Total additional charge (R) is equal to the sum of R1,
R2 and R3. Calculate the refrigerant charge according
to the following formula:
R = R1 + R2+ R3.
Determine the total refrigerant charge of the system:
Total charge (Mc) = factory additional charge = R0
+ R.
The factory charge (R0) can be obtained from Table 15-5.
Table 15-5
Model
Factory charge
Refrigerant/kg
8kW
1.4
10kW
1.8
12kW
2.2
14kW
2.4
16kW
2.4
●
The total refrigerant charge of the system,
including the factory charge and additional
charge, must not exceed the maximum design
refrigerant charge of 7.7 kg.
Warning
●
The maximum refrigerant charge is related to
types of the IDUs, which have different installation
heights.
●
The actual charges shall not exceed the maximum
refrigerant limits of all rooms.
●
The maximum refrigerant limit described in
Table 1 applies to unventilated areas. For
adding additional measures, such as areas with
mechanical ventilation, please refer to applicable
legislation for the maximum refrigerant limit.
Caution
●
Make sure all connected indoor units have been
identified.
●
Hoses or lines shall be as short as possible to
minimize the amount of refrigerant contained in
them.
●
Label the system when charging is complete (if it
is not already labeled).
●
If the power supply of some units is off, the
charging program cannot be completed normally.
●
Make sure the power supply is turned on 12
hours before operations so that the crankcase
heater is properly energized. This is also to
protect the compressor.
NOTE
Summary of Contents for KMF-80 DVR5
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