LG Multi F Install page 4

Piping Selection
ACR-rated, seamless phosphorous deoxidized copper (UNS C12200 DHP class) rated at the system working pressure is the only approved refrig-
erant pipe material for LG Multi F / Multi F MAX products. Approved piping will be marked "R-410A rated" along the length of the tube.
• Wall thickness must meet local code requirements and be approved for
a maximum operating pressure of 551 psi.
Handling the Piping
To avoid operation failure, a Multi F / Multi F MAX system CANNOT have contaminants or moisture in the piping network. Piping must be kept
clean, dry, and air tight. Commercially available piping, however, often contains dust and other materials. Clean it with a dry inert gas, and keep it
capped until ready for installation. While installing, prevent dust, water, or other contaminants from entering the piping. When cutting the piping,
hold it so copper shavings do not fall into it, and properly remove all burrs with a de-burring tool. Ream all piping to its full inside diameter; correct-
ly reamed piping will provide an excellent surface for a tight seal.
When bending piping, try to keep the number of bends to a minimum, and use the largest radius possible to reduce the equivalent length of
installed pipe. If an obstacle is in the path of the planned refrigerant pipe run, it is preferable to route the pipe over the obstacle, with the length
of the horizontal section of pipe above or below the obstacle be a minimum of three (3) times the longest vertical rise (or fall) at either end of the
segment.
Piping Expansion
Under normal operating conditions, the vapor pipe temperature of a
Multi F / Multi F MAX system can vary as much as 180°F. With this
large variance in pipe temperature, the designer must consider pipe ex-
pansion and contraction to avoid pipe and fitting fatigue failures. When
a segment of pipe is mounted between two fixed points, provisions
must be provided to allow pipe expansion to naturally occur, generally
by expansion Loops or U-bends.
Piping Components
Only LG supplied Y-branch fittings can be used to join one pipe segment to two (2) or more segments.
Third-party or field-fabricated components such as Tee's, Y-fittings, or other branch fittings are not per-
mitted. The only field-provided fittings allowed in a Multi F / Multi F MAX piping system are 45° and 90° long
radius elbows and full port ball valves (if applicable).
Multi F MAX Y-Branch Kit
The LG-supplied Y-Branch kit PMBL5620 MUST be
used when installing two (2) branch distribution
units in parallel on one (1) Multi F MAX system.
Each Y-Branch kit includes two (2) Y-branches (one
for the liquid line and one for the vapor line) and
insulation covers.
Y-branches may be installed in horizontal or ver-
tical configurations. When installed vertically, the
straight-through leg must be within ±3° of plumb.
When installed horizontally, the straight-through
leg must be within ±5° rotation.
Y-branches must be properly installed following instructions in the applicable LG manual. Y-branches must
always be installed with the single port facing the outdoor unit and the two-port end facing the branch dis-
tribution units. Do not install Y-branches backwards as refrigerant flow cannot make U-turns. The Y-branch kit must be located at least three
(3) feet from the outdoor unit. Provide a minimum of 20 inches between a Y-branch and the branch distribution unit.
Piping Supports
A properly installed piping system is adequately supported to avoid piping sags (sagging pipes become oil traps that lead to equipment malfunc-
tion). Field-provided piping supports must be designed to meet local codes. As necessary, place supports closer for segments where sagging could
potentially occur. Maximum spacing of pipe supports must meet local codes, but if there are no specifications in the local codes, then the piping
must be supported:
• Minimum of 20 inches recommended between
long radius 90 degree elbows, and between the
Y-branch and the branch distribution unit.
• Maximum 5 feet on center for straight seg-
ments of pipe up to 3/4 inches outside dia. size.
• Maximum of 6 feet on center for pipe up to 1
inch outside diameter size.
• Wherever the pipe changes direction, place a
hanger within 12 inches on one side and within
12 to 19 inches of the bend on the other side.
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Piping, continued.
• LG recommends soft copper use to be limited to 1/2 inches. Use hard
drawn for larger sizes to avoid sags and kinks that lead to oil trapping.
Flaring the Piping
When flaring the piping, use a dedicated R-410A
flaring tool; use only synthetic oil between the
nut and the flare (not inside the piping) to achieve
correct torque and prevent leaks. Flares must be
deeper to handle the higher pressures of R-410A.
When brazing the piping, always use 15% silver
braze and a nitrogen purge. Similar to piping medi-
cal gas, flow the nitrogen through the piping at 1to
3 psig to prevent oxidation.
Indoor Unit Y-Branch Horizontal Configuration.
Straight-through Leg
Y-branch Inlet
Examples of Piping Supports.
Y-branch Installation Alignment
Specification.
Vertical Up
Configuration
Branch Leg
±5°
Horizontal
Plane
±5°
Within ± 3°
Rule for Changes in Piping
Direction.
Proper R-410A
Flare.
Vertical Down
Configuration
Within ± 3°
Max.
12"
12" – 19"