Our house used to have a fur-down A/C unit that fed a series of rigid ducts made with duct board. We'd like to replace a vent in our bathroom (5' x 11') with a 5" flex duct. We'd like to replace a vent in our kitchen with a 7" flex duct.
Based on the research I've done, It seems we can take a single 8" flex duct off the output plenum and split it into a 5" flex and 7" flex.
Do all those sizes seem appropriate for the rooms? Can I really split an 8" flex into a 5" flex and 7" flex?
I'm also wondering if 7" would be big enough for the kitchen so I'm considering going with a 8" flex. So could I run a 10" flex and split it into a 5" flex and 8" flex?
Are there any issues with using a flex duct as a "trunk" line to the splitter? Or would it be better to use a rigid duct to the splitter and then go with flex lines from there?