Multi F Outdoor Unit Engineering Manual
Table Of Contents
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 ad-
ditional 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.
Additionalcharge(lbs.) =(InstalledLengthofBranch[A]–ChargelessPipeLength[A])xa
+(InstalledLengthofBranch[B]–ChargelessPipeLength[A])xa
+(InstalledLengthofBranch[C]–ChargelessPipeLength[A])xa
+(InstalledLengthofBranch[D]–ChargelessPipeLength[A])xa
- CF (Correction Factor) x 5.29
Outdoor Unit Model
Max. Piping Length for One
Branch (ft.)
Max. Total System Piping
Length (ft.)
Chargeless Pipe Length
per Branch (A) (ft.)
Additional Charge Needed
(a) (oz./ft.)
LMU187HV 82 164 24.6 0.22
LMU247HV 82 246 24.6 0.22
LMU369HV 82 246 24.6 0.22
Outdoor Unit
Factory Charge
lbs. of R410A
LMU187HV 4.19
LMU247HV 4.63
LMU369HV 7.72
LMU540HV 9.7
Table 170: Outdoor Unit Factory Charge.
Multi F Systems
• 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 171: MultiFOutdoorUnitPipingSpecications.
Each branch pipe
A = 82 ft.
B = 16 ft.
C = 49 ft.
Additional Charge
= (82 - 25) x 0.22
+ (16 - 25) x 0.22
+ (49 - 25) x 0.22
– (4 - 3) x 5.29
= 10.55 oz.
A
B
C
9,000
LMU369HV
9,000
9,000
Figure 53: Multi F Additional Refrigerant Charge Example.
Due to our policy of continuous product innovation, some specications may change without notication.
©LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. “LG” is a registered trademark of LG Corp.
202 | DESIGN & PRACTICES
Multi F and Multi F MAX Heat Pump System Engineering Manual
MULTI
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MAX
MULTI
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