LG Multi F - Branch Box - 4 Ports - Alternative Primary Port Size for Outdoor Units Above 36K BTU

Q: What is the difference between the LG PMBD3641 and the PMBD3640?

Also - I know you can buy adapters, but the output ports on these branch units is 1/4X3/8. Most of the LG units larger than 12K BTU's require 1/4X1/2. Does this impact performance by stepping the size down? Do you recommend stepping down at the branch box or at the wall unit?
by Chris from Washington on October 19, 2016

A: The PMBD3640 is the standard option for an LG 4 port brnach box. The PMBD3641 includes a larger port specifically for use with the a 36k BTU indoor unit. Unless you are using one of these indoor units, there is no benefit to using the PMBD3641.

LG includes any necessary port adapters with the air handlers,so they do not need to be purchased separately. They specify specific line set sizes based on the capacity of the indoor unit, and the size of the line set, along with the connections available on the indoor unit and branch box, dictates the location of the adapters. The adapters may introduce a minimal restriction, but this is insignificant to the efficiency or performance of the system. Using a line set size other than the one LG prescribes could result in poor performance.
by Chris, Product Expert