P5417009-rev.6
71
8.4 Additional Refrigerant Charge Calculation
Table 8.1 Additional Refrigerant Charge Calculation
No. Symbol Step
Additional
Charge
1 W1 Additional Refrigerant Charge Calculation for Liquid Piping [W1 lbs (kg)]
Pipe Diameter
[inch (mm)]
Total Piping Length
[ft (m)]
Refrigerant Charge
for 1 ft Pipe [lbs/ft (kg/m)]
Additional Charge
[lbs (kg)]
7/8 (22.2) × 0.24 (0.36) =
3/4 (19.05) × 0.17 (0.26) =
5/8 (15.88) × 0.11 (0.17) =
1/2 (12.7) × 0.074 (0.11) =
3/8 (9.52) × 0.038 (0.056) =
1/4 (6.35) × 0.016 (0.024) =
Total Additional Charge For Liquid Piping =
If the calculated charge above is less than the charge shown in the table below, then add
W1 as the additional refrigerant charge shown below.
Outdoor Unit Capacity
(MBH)
072-144 168, 192 216-288 312, 336 360 384-432
Minimum Additional
Ref. Charge [lbs (kg)]
6.6
(3.0)
8.8
(4.0)
13.2
(6.0)
15.4
(7.0)
17.6
(8.0)
19.8
(9.0)
lbs (kg)
2 W2 Depending on connection of indoor unit capacity, additional refrigerant charge is required.
Select adequate refrigerant charge from the table below.
Additional Refrigerant Charge for Each Indoor Unit Connected [W2 lbs (kg)]
Indoor Unit Capacity
(MBH)
006, 008 012-054
Additional Ref. Charge
[lbs (kg)/unit]
0.7
(0.3)
1.1
(0.5)
Maximum additional refrigerant charge must not exceed 13.2 lbs (6.0kg).
lbs (kg)
3 W3 Calculation Method for Additional Refrigerant Charge [W3 lbs (kg)]
The additional refrigerant charge must be 2.2 lbs (1.0kg) per indoor unit which is 060 MBH
or more.
unit × 2.2 lbs (1.0kg)/unit =
lbs (kg)
4 W4 The Ratio of Indoor Unit Connection Capacity (Indoor Unit Total Capacity/Outdoor Unit
Capacity) Additional Charge [W4 lbs (kg)]
Determine the ratio of indoor unit connection capacity.
Condition Additional Charge [lbs (kg)]
I.U. Capacity Ratio is less than 100% 0.0 (0.0)
I.U. Capacity Ratio is 100% or more 1.1 (0.5)
lbs (kg)
5 W5 Depending on connection of outdoor unit model, additional refrigerant charge is required.
Select adequate refrigerant charge from the table below. [W5 lbs (kg)]
Outdoor Unit Model Additional Charge [lbs (kg)]
(H,Y)VAHR192B(3,4)2S
2.2 (1.0)(H,Y)VAHR336B(3,4)2S
(H,Y)VAHR360B(3,4)2S
lbs (kg)
6 W6 If Change-Over Boxes Multiple Branch type are connected, additional refrigerant charge is
required.
Select adequate refrigerant charge from the table below. [W6 lbs (kg)]
Change-Over Box Model Additional Charge [lbs (kg)/unit]
COB04M132B22S 0.3 (0.1)
COB08M264B22S 0.5 (0.2)
COB12M264B22S 0.7 (0.3)
lbs (kg)
7 WT
Calculation of Additional Charge [WT lbs (kg)] =
W1 + W2 + W3 + W4 + W5 + W6 =
lbs (kg)
Ensure that the total additional charge WT does not exceed the maximum additional refrigerant charge as shown in
the table on the following page.
Although this unit has been charged with refrigerant, an additional refrigerant charge is required according to
piping length.
Determine what additional charge of refrigerant according to the following procedures, and charge it into the
system. Record the additional refrigerant charge to facilitate maintenance and servicing activities thereafter.
(1) Calculating Method of Additional Refrigerant Charge [WT lbs (kg)]
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