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.
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