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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:
CAUTION
DO NOT
mix refrigerant types.
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)
.
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: Ø 6.35 (ø 0.25”)
R32:
(Pipe length – standard length) x 12g/m
(Pipe length – standard length) x 0.13oZ/ft
R290:
R290:
(Pipe length – standard length) x 10g/m
(Pipe length – standard length) x 0.10oZ/ft
Liquid Side: Ø 9.52 (ø 0.375”)
R32:
(Pipe length – standard length) x 24g/m
(Pipe length – standard length) x 0.26oZ/ft
(Pipe length – standard length) x 18g/m
(Pipe length – standard length) x 0.19oZ/ft
R410A:
R410A:
(Pipe length – standard length) x 15g/m
(Pipe length – standard length) x 0.16oZ/ft
(Pipe length – standard length) x 30g/m
(Pipe length – standard length) x 0.32oZ/ft
R22:
(Pipe length – standard length) x 20g/m
(Pipe length – standard length) x 0.21oZ/ft
R22:
(Pipe length – standard length) x 40g/m
(Pipe length – standard length) x 0.42oZ/ft
