Air Evacuation
Note on Adding Refrigerant
Some systems require additional charging depending on pipe lengths. The standard 
pipe length varies according to local regulations. For example, in North America, the 
standard pipe length is 7.5m (25’). In other areas, the standard pipe length is 5m (16’). The 
refrigerant should be charged from the service port on the outdoor unit’s low pressure valve. 
The additional refrigerant to be charged can be calculated using the following formula:
ADDITIONAL REFRIGERANT PER PIPE LENGTH
Connective Pipe 
Length (m)
Air Purging 
Method
Additional Refrigerant
≤ Standard pipe 
length
Vacuum Pump N/A
> Standard pipe 
length
Vacuum Pump
Liquid Side: ø6.35 (ø0.25”)
R32:
(Pipe length – standard length) × 12g/m
(Pipe length – standard length) × 0.13oZ/ft
R290:
(Pipe length – standard length) × 10g/m
(Pipe length – standard length) × 0.10oZ/ft
R410A:
(Pipe length – standard length) × 15g/m
(Pipe length – standard length) × 0.16oZ/ft
R22:
(Pipe length – standard length) × 20g/m
(Pipe length – standard length) × 0.21oZ/ft
Liquid Side: ø9.52 (ø0.375”)
R32:
(Pipe length – standard length) × 24g/m
(Pipe length – standard length) × 0.26oZ/ft
R290:
(Pipe length – standard length) × 18g/m
(Pipe length – standard length) × 0.19oZ/ft
R410A:
(Pipe length – standard length) × 30g/m
(Pipe length – standard length) × 0.32oZ/ft
R22:
(Pipe length – standard length) × 40g/m
(Pipe length – standard length) × 0.42oZ/ft
For R290 refrigerant unit, the total amount of refrigerant to be charged is no more than: 
387g (<=9000Btu/h), 447g (>9000Btu/h and <=12000Btu/h), 547g (>12000Btu/h and 
<=18000Btu/h), 632g (>18000Btu/h and <=24000Btu/h).
CAUTION 
DO NOT mix refrigerant types.
 Page 20-GB