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Refrigerant Piping Connections
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The proper design and installation of the refrigerant piping system 
is a critical element of the Multi V Space II system. Multi V Space II 
requires two pipes between system components – a liquid line and 
a vapor line.  A properly designed refrigerant piping system ensures 
that refrigerant is delivered to the evaporator coils electronic expan-
sion valve (EEV) in a pure liquid state free of gas bubbles.  A proper 
design also ensures a sufficient refrigerant gas flow rate in the vapor 
line that eliminates the possibility of refrigeration oil from collecting in 
the vapor lines.
Refrigerant Piping Quality Assurance
LG’s LATS Multi V software makes designing the refrigerant system 
easy.  LATS Multi V is a Windows
®
-based application that assists the 
engineer in the design of the refrigeration distribution pipe system, 
verifies the design complies with pipe design limitations, applies 
capacity correction factors, and calculates the system refrigerant 
charge. The piping system can be entered manually into LATS from 
a one-line pipe diagram.
To ensure that the refrigerant piping design meets LG’s quality 
standards, a LATS refrigerant piping design must be provided 
with every Multi V Space II order.  Following the installation, if 
any changes or variations to the design are necessary, a new 
LATS file must be created and provided to LG prior to system 
commissioning to ensure the proper pipe size has not changed.
Adjusting LATS Multi V Output for 
Altitude
When a system is installed at elevations significantly above sea 
level, the designer must also consider the impact air density has on 
the capacity of the indoor and Space II units. LATS does not de-rate 
indoor unit capacity for high altitude applications. Locally accepted 
altitude correction factors must be applied to indoor unit capacities.
Design Choices
LATS Multi V software is flexible, offering the HVAC system engineer 
a choice of two design methods: CAD mode and Tree mode.
CAD Mode
Using the CAD mode, the refrigerant pipe design and layout work is 
performed concurrently.  Simply import a copy of a plan view drawing 
(.dwg format) for floor of the structure into LATS Multi V software. 
Multi V air-source units, heat recovery units, and indoor units can be 
selected from drag and drop lists and placed on the floor plan draw-
ing(s), and interconnecting pipes between system components will 
be drafted directly on the drawing set.  LATS will size the refrigerant 
piping, certify the design, and provide a detailed materials report and 
system schematic. Use the export feature to create a CAD file (.dxf 
format) that can subsequently be imported into the building design 
drawings. 
• Import the building’s architectural CAD (.dwg and .dxf format).
• Import building loads from an external file (.xls and .xlsx format).
• Layout refrigerant piping directly onto an overlay of the building drawing.
• Automatically calculates pipe segment lengths based on drawing layout.
• Creates an export image file for import to the building drawing set 
(.dxf format).
• Generates a system engineering report (.xls or .xlsx format).
Tree Mode
Using the TREE mode, the engineer can quickly create a one- 
line schematic drawing of the Multi V system.  Integration of the 
engineered pipe system into the building drawings is done at a later 
date by the draftsperson using standard drafting software tools. 
• Import building loads from an external file (.xls format).
• System components selected using an easy drag and drop  
process.
• Automatically analyzes and checks the design complies with most 
piping design limitations.
• Sizes refrigerant piping.
• Generates a system engineering report (.xls format).
In either case, LATS Multi V software generates a report file (.xls 
format) containing project design parameters, cooling and heating 
design day system component performance, and capacity data. The 
report calculates the system combination ratio, calculates the system 
refrigerant charge, and provides detailed bill of material information 
including a list of Multi V outdoor units, air handlers, control  
devices, accessories, refrigerant pipe sizes segregated by building, 
by system, by pipe size, and by pipe segments.
Figure 30:  Screenshot of LATS Pipe System Design Tool in Tree Mode.
Required LATS Multi V Piping Design Software File
REFRIGERANT PIPING CONNECTIONS