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3. Allowable length/height difference of refrigerant piping
Note: In case of connecting method in Example 2, a large amount of
refrigerant and refrigerant oil may return to the master unit. Therefore,
set the T-shape joint so that oil does not enter directly.
System restrictions
Max. No. of combined outdoor units 4 units
Max. capacity of combined outdoor units 48 hp
Max. No. of connected indoor units 48 units
Max. capacity of combined H
2
≤ 15 135%
indoor units H
2
> 15 105%
Note 1: Combination of outdoor units: Master unit (1 unit) + slave units (0 to 3 units).
Master unit is the outdoor unit nearest to the connected indoor units.
Note 2: Install the outdoor units in order of capacity.
(Master unit ≥ slave unit 1 ≥ slave unit 2 ≥ slave unit 3)
Note 3: Refer to outdoor unit combination table on page 7.
Note 4: Piping to indoor units shall be perpendicular to piping to the master outdoor unit as in
Example 1. Do not connect piping to indoor uints in the same direction as the master
outdoor unit in Example 2.
Allowable length and height difference of refrigerant piping
Allowable value Piping section
Piping length Total extension of pipe (liquid pipe, actual length) 300 m LA + LB + La + Lb + Lc + Ld + L1 + L2 + L3 + L4+
L5 + L6 + L7 + a + b + c + d + e + f + g + h + i + j
Farthest piping length L (*) Actual length 150 m LA + LB + Ld + L1 + L3 + L4 + L5 + L6 + j
Equivalent length 175 m
Equivalent length of farthest piping from 1st branching Li (*) 65 m L3 + L4 + L5 + L6 + j
Equivalent length of farthest piping between outdoor units LO (*) 25 m LA + LB + Ld, (LA + Lb, LA + LB + Lc)
Max. equivalent length of main piping (***) 85 m L1
Max. equivalent length of outdoor unit connection piping 10 m Ld, (La, Lb, Lc)
Max. actual length of indoor unit connection piping 30 m a, b, c, d, e, f, g, h, i, j
Height difference Height between indoor Upper outdoor unit 50 m ——
and outdoor units H1 Lower outdoor unit 40 m (**) ——
Height between indoor units H2 30 m ——
Height between outdoor units H3 5 m ——
* (D) is outdoor unit farthest from 1st branching, and ( j ) is indoor unit farthest from 1st branching.
** If the height difference (H2) between indoor units exceeds 3 m, set below 30 m.
*** If the maximum combination capacity of the outdoor units is 46 hp or more, the maximum equivalent length is restricted up to 70 m.
D slave
unit 3
Slave
unit 1
Slave
unit 2
Slave
unit 1
Slave
unit 2
C slave
unit 2
B slave
unit 1
A master
unit
Master
unit
Master
unit
Connecting
piping of
outdoor unit
Outdoor unit
Height difference
between outdoor
units H3 ≤ 5 m
Height difference
betweeen outdoor
units H1 ≤ 50 m
T-shape branching
joint
Main
piping
Main connecting piping between outdoor units
Length corresponding to farthest piping
between outdoor units LO ≤ 25 m
Branching piping L2
1st branching
section
Branching
header
Connecting piping of indoor unit
Indoor unit
Equivalent length corresponding to farthest piping L ≤ 175 m
Equivalent length corresponding to farthest piping after 1st branching Li ≤ 65 m
Indoor unit
Height difference
between indoor
units H2 ≤ 30 m
Example 1
Example 2
Y-joint
La
Lb Lc
LA LB
Ld
L1
L3
L4
L6
L5