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8.3
Additional Refrigerant Charge Calculation
Although refrigerant has been charged into this unit, additional refrigerant charge is required according to
piping length.
Determine the additional refrigerant quantity according to the following procedure, and charge it into the system.
Record the additional refrigerant quantity to facilitate maintenance and servicing activities thereafter.
1. Calculating Method of Additional Refrigerant Charge (W kg)
No.
Symbol
1
W1
Additional Refrigerant Charge Calculation for Liquid Piping (W1 kg)
Pipe Diameter
2
W2
Additional Refrigerant Charge Calculation for Indoor Unit (W2 kg)
Additional refrigerant charge is 1kg/unit of 76KBtu/h and 96KBtu/h indoor unit.
Additional refrigerant charge of less than 76KBtu/h indoor units is not needed.
3
W3
The Ratio of Indoor Unit Connection Capacity (Indoor Unit Total Capacity/
Outdoor Unit Capacity) Additional Charge
Determine the ratio of indoor unit connection capacity.
• I.U.Capacity Ratio is less than 100% :
• I.U.Capacity Ratio is 100~115% :
• I.U.Capacity Ratio is 116~130% :
4
W
Note:
Ensure that the total additional charge should not be exceeded the max. additional refrigerant charge quantity
as shown in the table below.
< Max. Additional Refrigerant Charge Quantity >
Outdoor Unit (KBtu/ h)
Max. Additional Ref.
Charge Quantity (kg)
2. Charging Work
Charge refrigerant (R410A) into the system according to Item 8.4.
3. Record of Additional Charge
Total refrigerant charge of this system is calculated in the following formula.
Total Ref. Charge = W
This System
=
Total Additional Charge: W
Total Ref. Charge:
Date of Ref. Charge Work:
48
Table 8.1 Additional Refrigerant Charge Calculation
Total Piping Length
(m)
22.2
19.05
15.88
12.7
9.53
6.35
Total Additional Charge For Liquid Piping =
76 and 96 Total Indoor Unit Numbers
× 1.0kg/unit =
Condition
76/96
114
2 8.0
3 3.0
+
Wo
+
=
kg
kg
kg
/
/
Contents
Refrigerant Amount
Additional Charge
for 1m Pipe
m
×0.35 =
m
×0.25 =
m
×0.16=
m
×0.11 =
m
×0.056 =
m
×0.024 =
Additional Charge
Refrigerant Amount
0.0kg
0.5kg
1.0kg
Calculation of Additional Charge (W kg) =
136/154
38.5
Ref. Charge Amount of O.U. Before Shipment (W0) kg
Outdoor Unit (KBtu/ h)
76
96
114
136
154
Note:
• W0 is outdoor unit ref. charge before shipment.
• In case of the combination of the base unit, calculate the total
ref. charge before shipment of the outdoor units to be combined.
Additional Charge (kg)
(kg)
W1 + W2 +W3
172
190~229
42.0
4 6 .0
W0 Outdoor Unit Ref. Charge (kg)
6.5
6.5
6.5
9.9
9.0
10.5
kg
kg
kg
kg
250~460
52.0
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