Design of 3WAY VRF SYSTEM
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1. Model Selection and Capacity Calculator
Table 5 Refrigerant Charge Amount at Shipment (for outdoor unit)
BTU/h (kW) 72,000 (21.1) 96,000 (28.1) 120,000 (35.2) 144,000 (42.2)
Initial amount
oz (
g
) 293 (8,300) 293 (8,300) 353 (10,000) 416 (11,800)
Table 6 Indoor Unit Tubing Connection Size ( 1 – 52)
Unit: in. (mm)
Indoor unit type 7912 15 18 24 36 48 54
Distribution
joint-solenoid
valve kit tubing
Suction tubing ø5/8" (ø15.88)
Discharge tubing ø1/2" (ø12.7)
Liquid tubing ø3/8" (ø9.52)
Solenoid valve
kit-Indoor unit
tubing
connection
Gas tubing ø1/2" (ø12.7) ø5/8" (ø15.88)
Liquid tubing ø1/4" (ø6.35) ø3/8" (ø9.52)
*1: For the solenoid valve kits, use type 160 with parallel specifications. Branch the tubing before and after the solenoid valve kits.
1-5. Straight Equivalent Length of Joints
Design the tubing system by referring to the following table for the straight equivalent length of joints.
Table 7 Straight Equivalent Length of Joints
Unit: ft. (m)
Tubing size (in. (mm))
1/2"
(12.7)
5/8"
(15.88)
3/4"
(19.05)
7/8"
(22.22)
1-1/8"
(28.58)
1-3/8"
(34.92)
1-5/8"
(41.28)
90° elbow
1
(0.30)
1.1
(0.35)
1.4
(0.42)
1.6
(0.48)
1.9
(0.57)
2.5
(0.76)
2.8
(0.85)
45° elbow
0.8
(0.23)
0.9
(0.26)
1
(0.32)
1.2
(0.36)
1.4
(0.43)
1.8
(0.55)
2.0
(0.61)
U-shape tube bent (R2-3/8" – 4" (60 – 100mm))
3
(0.90)
3.4
(1.05)
4.1
(1.26)
4.7
(1.44)
5.6
(1.71)
7.4
(2.26)
8.4
(2.56)
Trap bend
7.5
(2.30)
9.2
(2.80)
10.5
(3.20)
12.5
(3.80)
15.4
(4.70)
19.2
(5.85)
22.3
(6.80)
Y- branch distribution joint
Equivalent length conversion not needed.
Ball valve for service Equivalent length conversion not needed.
Table 8 Refrigerant tubing (Existing tubing can be used.)
Tubing size (in. (mm))
* When bending the tubes, use a
bending radius that is at least 4 times
the outer diameter of the tubes.
In addition, take sufficient care to
avoid crushing or damaging the tubes
when bending them.
Material: O Material: O Material: O
Outer diameter Wall thickness Outer diameter Wall thickness Outer diameter Wall thickness
1/4" (6.35) 0.025 (0.635) 5/8" (15.88) 0.040 (1.016) 1-1/8" (28.58) 0.050 (1.27)
3/8" (9.52) 0.030 (0.762) 3/4" (19.05) 0.042 (1.0668) 1-3/8" (34.92) 0.055 (1.397)
1/2" (12.7) 0.035 (0.889) 7/8" (22.22) 0.045 (1.143) 1-5/8" (41.28) 0.060 (1.524)
1-6. Additional Refrigerant Charge
Additional refrigerant charge amount is calculated from the liquid tubing total length, combination number of outdoor unit and
refrigerant amount according to all indoor unit cooling capacity.
Required amount of additional refrigerant charge
= [(Necessary amount of additional refrigerant charge per ft. (m) of each size of liquid tube × its tube length) + (...) + (...)]
+ [Necessary amount of additional refrigerant charge per outdoor unit]
+ [Necessary amount of additional refrigerant charge for all indoor unit cooling capacity]
+ [(Necessary amount of additional refrigerant charge per ft. (m) of each size of discharge tube × its tube length) + (...) + (...)]
* Always charge accurately using a scale for weighing.
Table 9 Necessary Amount of Additional Refrigerant Charge Per ft. (or per meter), According to Liquid Tubing Size
Liquid tubing size
inch ø1/4" ø3/8" ø1/2" ø5/8" ø3/4" ø7/8"
(mm) (ø6.35) (ø9.52) (ø12.7) (ø15.88) (ø19.05) (ø22.22)
Additional amount
oz/ft. 0.279 0.602 1.38 1.99 2.78 3.93
(
g
/m) (26) (56) (128) (185) (259) (366)
Design of 3WAY VRF SYSTEM
1. Model Selecting and Capacity Calculator
1-4. Tubing Size
Table 2 Main Tubing Size (LA)
Between 1st distribution joint for outdoor unit and 1st distribution joint (for indoor unit)
Unit: in. (mm)
BTU/h
(kW)
72,000
(21.1)
96,000
(28.1)
120,000
(35.2)
144,000
(42.2)
168,000
(49.2)
192,000
(56.3)
216,000
(63.3)
240,000
(70.3)
264,000
(77.4)
288,000
(84.4)
312,000
(91.4)
336,000
(98.5)
360,000
(105.5)
Total system
tonnage
6810 12 14 16 18 20 22 24 26 28 30
Suction
tubing
ø3/4"
(ø19.05)
ø7/8"
(ø22.22)
ø1-1/8"
(ø28.58)
ø1-3/8"
(ø34.92)
ø1-5/8"
(ø41.28)
Discharge
tubing
ø5/8"
(ø15.88)
ø3/4"
(ø19.05)
ø7/8"
(ø22.22)
ø1-1/8"
(ø28.58)
Liquid tubing
ø3/8"
(ø9.52)
ø1/2"
(ø12.7)
ø5/8"
(ø15.88)
ø3/4"
(ø19.05)
* If future extension is planned, select the tubing diameter based on the total tonnage after extension.
However, extension is not possible if the resulting tubing size is three ranks higher.
* The balance tube (outdoor unit tube) diameter is ø1/4" (6.35mm).
* Type 1 tubing should be used for the refrigerant tubes.
Size of tubing (LO) between outdoor units
Select the size of tubing between outdoor units based on the main tubing size (LA) as given in the table above.
Table 3 Main Tubing Size After Distribution (LB, LC...)
Unit: in. (mm)
Total capacity
after distribution
Below BTU/h (kW)
24,200
(7.09)
54,600
(16.0)
85,300
(25.0)
102,400
(30.0)
124,200
(36.4)
143,300
(42.0)
162,400
(47.6)
200,600
(58.8)
Over BTU/h (kW)–
24,200
(7.09)
54,600
(16.0)
85,300
(25.0)
102,400
(30.0)
124,200
(36.4)
143,300
(42.0)
162,400
(47.6)
Tubing size
Suction tubing
ø5/8"
(ø15.88)
ø3/4"
(ø19.05)
ø3/4"
(ø19.05)
ø7/8"
(ø22.22)
ø1-1/8"
(ø28.58)
ø1-1/8"
(ø28.58)
ø1-1/8"
(ø28.58)
ø1-1/8"
(ø28.58)
Discharge tubing
ø1/2"
(ø12.7)
ø5/8"
(ø15.88)
ø5/8"
(ø15.88)
ø3/4"
(ø19.05)
ø3/4"
(ø19.05)
ø7/8"
(ø22.22)
ø7/8"
(ø22.22)
ø7/8"
(ø22.22)
Liquid tubing
ø3/8"
(ø9.52)
ø3/8"
(ø9.52)
ø3/8"
(ø9.52)
ø3/8"
(ø9.52)
ø1/2"
(ø12.7)
ø1/2"
(ø12.7)
ø1/2"
(ø12.7)
ø5/8"
(ø15.88)
Total capacity
after distribution
Below BTU/h (kW)
238,900
(70.0)
340,000
(99.6)
–
Over BTU/h (kW)
200,600
(58.8)
238,900
(70.0)
340,000
(99.6)
Tubing size
Suction tubing
ø1-1/8"
(ø28.58)
ø1-3/8"
(ø34.92)
ø1-5/8"
(ø41.28)
Discharge tubing
ø1-1/8"
(ø28.58)
ø1-1/8"
(ø28.58)
ø1-1/8"
(ø28.58)
Liquid tubing
ø5/8"
(ø15.88)
ø3/4"
(ø19.05)
ø3/4"
(ø19.05)
Table 4 Outdoor Unit Tubing Connection Size (
A
–
C
)
Unit: in. (mm)
BTU/h
(kW)
72,000
(21.1)
96,000
(28.1)
120,000
(35.2)
144,000
(42.2)
Suction tubing
ø3/4" *
1
(ø19.05) *
1
ø7/8" *
2
(ø22.22)*
2
ø1-1/8"
(ø28.58)
Brazing connection
Discharge
tubing
ø5/8" (ø15.88) ø3/4" (ø19.05) ø7/8" (ø22.22)
Flare connection
Brazing connection
Liquid tubing
ø3/8" (ø9.52) ø1/2" (ø12.7)
Flare connection
Balance tubing
ø1/4" (ø6.35)
Flare connection
ex.) Type 72
Liquid tube
Discharge tube Suction tube
Balance tube
Note: In case the total capacity of connected indoor units
exceeds the total capacity of the outdoor units,
select the main tubing size for the total capacity of
the outdoor units.
7'B⡿ྥࡅ:$<LQGE
TD831183-00_北米向け3WAY.indb 9 15/12/17 16:05:08
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