Fujitsu AUXG18KVLA Design & Technical Manual page 107

 Additional charging amount for Twin type
Pre-charge length < L1 + L2 + L3
The additional charging amount will be calculated as follows.
• A: Piping length (m) of liquid pipe with outside diameter of 9.52 mm (1/2 in)
• B: Piping length (m) of liquid pipe with outside diameter of 6.35 mm (3/8 in)
• Additional charging amount (g) = (A × 40) + (B × 20) - 1,200
NOTE: Do not remove refrigerant, even if the additional amount calculated is negative.
Example:
Indoor unit
24,000 Btu/h
Indoor unit
24,000 Btu/h
Liquid pipe diameter (mm)
9.52
6.35
Applying the formula,
(20 × 40) + (22 × 20) - 1,200 = 40
The additional charging amount is 40 g.
2-5. Additional charge calculation
L2: 15 m
Liquid pipe (mm) 6.35
Gas pipe (mm) 12.70
L3: 7 m
Liquid pipe (mm) 6.35
Gas pipe (mm) 12.70
Piping length (m)
- 99 -
L2
L3 L1
L1: 20 m
Liquid pipe (mm)
Gas pipe (mm)
20
22
Outdoor unit
54,000 Btu/h
9.52
15.88
Coefficient
A = 20
B = 22
2. Pipe design