LG Multi F Series Installation Manual page 80

FINAL INSTALLATION PROCEDURES
LG Multi F and Multi F MAX outdoor units ship from the factory with a charge of
R410A refrigerant. A trim charge will need to be added to take into account addition-
al piping length.
To determine the additional refrigerant that is needed, apply the formulas below,
and record the results. If the total additional refrigerant charge value is a negative
number, then an additional trim charge does not need to be added to the system.
Multi F Systems
Additional charge (lbs.) = (Installed Length of Branch [A] – Chargeless Pipe Length [L]) x a
+ (Installed Length of Branch [B] – Chargeless Pipe Length [L]) x a
+ (Installed Length of Branch [C] – Chargeless Pipe Length [L]) x a
+ (Installed Length of Branch [D] – Chargeless Pipe Length [L]) x a
- CF (Correction Factor) x 5.29
• Number of installed length of branches depends on the specifications of the outdoor unit model.
• CF = Maximum number of connectible indoor units – Total number of connected indoor units.
Table 35:
Min. to Max. Piping
Outdoor
Length for One
Unit Model
Branch (ft.)
LMU18CHV 9.8 to 82
LMU24CHV 9.8 to 82
LMU30CHV 9.8 to 82
LMU36CHV 9.8 to 82
Figure 100: Multi F Additional Refrigerant Charge Example.
Example: LMU36CHV
80
Max. Total System Chargeless Pipe Length
Piping Length (ft.) per Branch (L) (ft.)
164
246.1
246.1
246.1
A
B
C
Due to our policy of continuous product innovation, some specifications may change without notification.
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Table 34: Outdoor Unit Factory Charge.
Outdoor Unit
LMU18CHV
LMU24CHV
LMU30CHV
LMU36CHV
LMU480HV
LMU540HV
LMU600HV
Piping Length (No Additional
Refrigerant [ft])
24.6
24.6
24.6
24.6
Each branch pipe
9,000
A = 82 ft.
B = 16 ft.
C = 49 ft.
9,000
Additional Charge
= (82 - 24.6) x 0.22
9,000
+ (16 - 24.6) x 0.22
+ (49 - 24.6) x 0.22
- (4 - 3) x 5.29
= 10.82 oz.
MULTI
MULTI
Factory Charge
lbs. of R410A
3.96
3.96
6.18
6.18
9.7
9.7
12.3
Additional Charge
Needed (a) (oz./ft.)
49.2 0.22
73.8 0.22
98.4 0.22
98.4 0.22
F
F
MAX