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Table 6: DOAS unit connecting pipe from Y-Branch
Capacity ton
(kBtu/h)
Liquid pipe
OD
Low Pressure
Pipe OD
High Pressure
Pipe OD
10 (127)
1/2 in.
(12.7 mm)
1-1/8 in
(28.58 mm)
3/4 in
(19.05 mm)
Selection of Refrigerant Y-Branch Kits
LG Y-branch and kits are highly engineered devices
designed to evenly divide the flow of refrigerant, and are
used to join one pipe segment to two or more segments.
There are two types of Y-branches used in LG VRF
systems: Y-branches that combine two or three outdoor
units to make up one large capacity outdoor unit (also
known as multi frame connectors), or Y-branches used
with the units in the refrigerant piping system at each
transition
No substitutions on piping components
Only LG supplied Y-branch and header fittings can be
used to join one pipe segment to two or more segments.
Third-party or field-fabricated components such as
tee’s, Y-fittings, couplings, headers, or other branch
fittings are not permitted. The only field-provided fittings
allowed in a Multi V piping system are 45° and 90° long
radius elbows and full port ball valves(if applicable)
Do not install Y-branches backwards: refrigerant flow
cannot make U-turns through Y-branches. The
equivalent pipe length of each Y-branch (
1.6’) must be
added to each pipe segment entered into LATS piping
design software
Outdoor Unit Y-Branch Kits
Outdoor unit Y-branches can only be installed in a
horizontal or vertical UP configuration
The Vertical DOWN configuration is not permitted
When using Y-Branch kit at the first branch from the
outdoor units, choose from the following table in
accordance with the capacity of the outdoor unit
(see
“Table 4”)
DOAS unit Y-Branch Kits
Header is not allowed in DOAS Application
.
For Y-Braches other than the first branch, select the
proper branch kit model based on the total capacity of all
DOAS units connected after the refrigerant
Y-Branch kit model can be changed by DOAS unit
combination and Outdoor unit selection. Please refer the
“LATS HVAC” software selection
Table 9: System Piping Length
Length
Total Pipe Length
Longest actual pipe length
Equivalent pipe length
A+B+C+D+E
≤
3,280feet
(1,000m)
A+B+E
≤
492 feet (150m)
*656 feet(200m) conditional application
≤ 574 feet
1)
(175m)
*738 feet(225m) conditional application
L
Longest pipe Length after first branch
≤ 131 feet(40m) (295 feet(90m) conditional application)
Elevation 1
Elevation Difference(Outdoor Un
it ↔ DOAS Unit)
Height
≤
164 feet(50m)
Elevation 2
Elevation Difference(DOAS Unit
↔
DOAS Unit)
Height
≤
98 feet(30m)
Height 1
Elevation Difference (Outdoor Unit ↔ Outdoor Unit)
≤ 16.4 feet
Distance between Outdoor Unit to Outdoor Unit
≤ 33 feet (Max. 43feet for outdoor unit ≥ 12 tons)
Distance between fittings and Indoor Unit
≥ 20 inches
Distance between fittings and Y-branch
≥ 20 inches
Distance between two Y-branch
≥ 20 inches
1) Assume equivalent pipe length of Y-branch is 1.6 feet, and equivalent pipe length of header is 3.3 feet.
Conditional Applications
Conditional applications are computed in LATS. See below for an explanation of when pipes are upsized.
If the equivalent length between the first Y-branch to the farthest DOAS
unit is >131 feet (maximum 295 feet):
•
Pipe segment diameters between the first branch and the last branch must be sized up by one. This applies to both liquid and
low / high vapor pipes. If the next size up is not available, or if the pipe segment diameters are the same as main pipe (A)
diameters, sizing up is not possible.
•
While calculating total refrigerant piping length, pipe (B) segment lengths between the first Y-branch and second Y-branch, and
between the second Y-branch and the heat recovery unit must be calculated by two.
[Length of pipe from outdoor unit to farthest DOAS unit (A+B+C+E)]
– [Length of pipe from outdoor unit to closest DOAS unit (A+C)]
≤ 131 feet
