Engineering Manual

REFRIGERANT PIPING DESIGN
Refrigerant Charge
Multi F MAX Systems
Outdoor Unit Model
Main Piping Length Branch Piping Length
Chargeless Pipe Length of
Main Pipe (L) (ft.)
Additional Charge Needed
(a) (oz./ft.)
Chargeless Pipe Length
per Branch Pipe (B) (ft.)
Additional Charge Needed
(b) (oz./ft.)
LMU540HV 16.4 0.54 16.4 0.22
Table 113:Multi F MAX Outdoor Unit Piping Specications.
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
Figure 263:Multi F MAX Additional Refrigerant Charge Example.
B3
18,000 9,000 9,000
LMU540HV
•Total main pipe (A) = 60 ft.
•Each branch pipe
B1 =
B2 =
B3 =
B4 =
B5 =
Additional Charge
= (60 - 16.4) x 0.54
+ (49 - 16.4) x 0.22
+ (17 - 16.4) x 0.22
+ (17 - 16.4) x 0.22
+ (10 - 16.4) x 0.22
+ (23 - 16.4) x 0.22
– (8 - 5) x 3.53
= 20.43 oz.
A
49 ft.
17 ft.
17 ft.
10 ft.
23 ft.
BD Unit
BD Unit
9,000 18,000
A
A
B1 B2
B4 B5
Due to our policy of continuous product innovation, some specications may change without notication.
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DESIGN & PRACTICES | 197
Refrigerant Piping Design and Best Practices
MULTI
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MULTI
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