When does a duct trunk become a branch?

Hi,Am designing ducting system  attached to a Fujitsu 12k mini-split.All ducts and fittings metal except for flex, last couple feet, and attched to wall registers.Design looks good. However, I am… Hi,Am designing ducting system  attached to a Fujitsu 12k mini-split.All ducts and fittings metal except for flex, last couple feet, and attched to wall registers.Design looks good. However, I am…Read MoreGreenBuildingAdvisor