Refrigerant Charge - LG MULTI F Engineering Manual

REFRIGERANT PIPING DESIGN

Refrigerant Charge

LG Multi F and Multi F MAX outdoor units ship from the factory with a charge of
R410A refrigerant. A trim charge may need to be added to take into account
additional 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 connectable indoor units – Total number of connected indoor units.
Table 112:Multi F Outdoor Unit Piping Specifications.
Outdoor Unit Model
LMU18CHV
LMU24CHV
LMU36CHV
Figure 262:Multi F Additional Refrigerant Charge Example.
Example: LMU36CHV
196 | DESIGN & PRACTICES
Min. to Max. Piping Length Max. Total System Piping
for One Branch (ft.)
10 to 82
10 to 82
10 to 82
Due to our policy of continuous product innovation, some specifications may change without notification.
©LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. "LG" is a registered trademark of LG Corp.
Table 111:Outdoor Unit Factory Charge.
Chargeless Pipe Length
Length (ft.) per Branch (L) (ft.)
164
246.1
246.1
9,000
A
9,000
B
9,000
C
MULTI
MULTI
Factory Charge
Outdoor Unit
lbs. of R410A
LMU18CHV
LMU24CHV
LMU36CHV
LMU540HV
Additional Charge Needed
(a) (oz./ft.)
24.6
24.6
24.6
Each branch pipe
A = 82 ft.
B = 16 ft.
C = 49 ft.
Additional Charge
= (82 - 24.6) x 0.22
+ (16 - 24.6) x 0.22
+ (49 - 24.6) x 0.22
- (4 - 3) x 5.29
= 10.82 oz.
F
F
MAX
3.96
3.96
6.18
9.7
0.22
0.22
0.22