Westinghouse WHU09DHA21S, Service Manual, Page: 22 / 97

Piping work and refrigerant charge
Completion
of Ref.
Piping
Repairing
of Leakage
Part
Check of
Pressure
Decrease
Applying
Nitrogen
Gas
Pass
Procedure
Air tight procedure
Although refrigerant has been charged into this unit, additional refrigerant charge is
required according to the piping length.
•
The additional refrigerant precharge quantity should be determined and charged into the system
according to the following procedure.
•
Record the additional refrigerant quantity in order to facilitate maintenance and servicing activities.
Refrigerant charge before shipment (W0 (kg))
W0 is the outdoor unit refrigerant charge before shipment
；
Xg is additional refrigerant outdoor unit needed to charge according to piping length during
installation.
Model
Refrigerant
precharged before
shipment
(W0(
oz/
g))
Total refrigerant pipe length
0
～
2
4.6
ft
(0 ～ 7.5 m)
Long
er
than
2
4.6
ft (7.
5 m
)
9K
33.5/0.95
0g
Additional refrigerant charge=
(L-24.6)×0.161 oz/ft
18K
56.44/1.6
0g
36K
111.2/3.15
0g
12K
45.9/1.3
0g
24K
91.7/2.6
0g
Additional refrigerant charge=
(L-24.6)×0.376 oz/ft
Air tight test
Additional refrigerant charge
Do use nitrogen when performing air-tight test.
Connect the gauge manifold using charging hoses with a nitrogen cylinder to the check joints of
the liquid line and the gas line stop valves. Perform the air-tight test. Don't open the gas line stop
valves. Apply nitrogen gas pressure of 4.3MPa. Check for any gas leakage at the flare nut
connections, or brazed parts by gas leak detector or foaming agent. It is OK if gas pressure does
not decrease. After the air tight test, release nitrogen gas.
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