Fujitsu AUXG22KVLA Design & Technical Manual page 108

 Additional charging amount for Triple type
Pre-charge length < L1 + L2 + L3 + L4
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
18,000 Btu/h
Indoor unit
18,000 Btu/h
Indoor unit
18,000 Btu/h
Liquid pipe diameter (mm)
9.52
6.35
Applying the formula,
(10 × 40) + (15 × 20) - 1,200 = -500
The calculated value is negative. Do not add or remove any refrigerant.
2-5. Additional charge calculation
L2
L3
L4
L2: 5 m
Liquid pipe (mm) 6.35
Gas pipe (mm) 12.70
L3: 5 m
Liquid pipe (mm) 6.35
Gas pipe (mm) 12.70
L4: 5 m
Liquid pipe (mm) 6.35
Gas pipe (mm) 12.70
Piping length (m)
- 100 -
L1
L1: 10 m
Liquid pipe (mm)
Gas pipe (mm)
10
15
Outdoor unit
54,000 Btu/h
9.52
15.88
Coefficient
A = 10
B = 15
2. Pipe design