REFRIGERANT PIPING DESIGN
Piping Design Guideline Summary
The proper design and installation of the refrigerant piping system is a critical element of a Multi V system. As detailed on page 102, LG
provides engineers LG Air Conditioner Technical Solution (LATS) software to help design LG Multi V air conditioning systems. The following
pages are examples of manual pipe size calculations for Multi V refrigerant piping systems.
The information represents how LATS Multi V Piping Design software works when designing the piping system for Multi V
heat pump and heat recovery units. It should not replace the use of LG's LATS Multi V complimentary selection software, but
should instead be used in conjunction with it. Contact your LG representative to obtain a copy of the software and the user's
Refrigerant Piping System Quality Assurance
To ensure that the refrigerant piping design meets LG's quality standards, a LATS refrigerant piping design software report must be provided
with every Multi V IV order. Following the installation, if any changes or variations to the design were necessary, an "as-built" LATS piping
design software report must be provided to LG prior to system commissioning.
Systems that are close to the standard application limits may be converted into a conditional application by field changes to pipe equivalent
lengths. User should always check the LATS report actual pipe layout versus pipe limits. The user may want to increase pipe lengths when
conditions close to the standard application limits are present, forcing increased pipe diameters seen in conditional applications to be used
and avoiding pipe changes due to field installation variations.
done with caution and ALWAYS VERIFIED in LATS MULTI V SOFTWARE before supplies are purchased or installed. Doing so ensures
Creating a Balanced Piping System
Unlike designing duct-work or chilled and hot water pipe systems where balancing dampers, ball valves, orifices, circuit setters, or other
flow control devices can be installed to modify or balance the flow of cooling medium, these cannot be used in a VRF system. Therefore,
variable refrigerant flow systems have to be designed to be "self balanced." Balanced liquid refrigerant distribution is solely dependent on
the designer choosing the correct pipe size for each segment. Pipe sizing considerations include pipe length, pipe segment pressure drop
relative to other pipe segments in the system, type and quantity of long radius elbows, bends present, fitting installation orientation, and end
use device elevation differences.
It is imperative the designer avoids creating excessive pressure drop. When liquid refrigerant is subjected to excessive pressure drop, liquid
valve (EEV) results in a loss of system control and causes damage to the valve. The pipe system must be designed in a manner that avoids
the creation of unwanted vapor.