LG MULTI F Engineering Manual page 197

F
MULTI
F
MULTI MAX
Multi F MAX Systems
Additional charge (lbs.) = (Total Main Piping Length [A] - Chargeless Pipe Length of Main Pipe [L]) x a
+ (Installed Length of Branch [B1] – Chargeless Pipe Length [B]) x b
+ (Installed Length of Branch [B2] – Chargeless Pipe Length [B]) x b
+ (Installed Length of Branch [B3] – Chargeless Pipe Length [B]) x b ...
- CF (Correction Factor) x 3.53
• Number of installed length of branches depends on system specifications.
• CF = Maximum number of connectable indoor units – Total number of connected indoor units
Table 113:Multi F MAX Outdoor Unit Piping Specifications.
Outdoor Unit Model
LMU540HV
Figure 263:Multi F MAX Additional Refrigerant Charge Example.
LMU540HV
A
A
BD Unit
Main Piping Length
Chargeless Pipe Length of Additional Charge Needed
Main Pipe (L) (ft.)
16.4
BD Unit
A
B1 B2
18,000 9,000
B4
9,000
Due to our policy of continuous product innovation, some specifications may change without notification.
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REFRIGERANT PIPING DESIGN
Chargeless Pipe Length
(a) (oz./ft.) per Branch Pipe (B) (ft.)
0.54
• Total main pipe (A) = 60 ft.
• Each branch pipe
B1 =
B2 =
B3 =
B4 =
B5 =
Additional Charge
B3
= (60 - 16.4) x 0.54
+ (49 - 16.4) x 0.22
9,000
+ (17 - 16.4) x 0.22
+ (17 - 16.4) x 0.22
+ (10 - 16.4) x 0.22
+ (23 - 16.4) x 0.22
B5
– (8 - 5) x 3.53
18,000
= 20.43 oz.
Refrigerant Charge
Branch Piping Length
Additional Charge Needed
(b) (oz./ft.)
16.4
49 ft.
17 ft.
17 ft.
10 ft.
23 ft.
DESIGN & PRACTICES | 197
0.22