I attempted to obtain as much information as I could for Joe S. 4 - 8" supply ducts off the plenum go into another plenum that has a barrier that I couldn't access, but would seem to go into a metal chase. Looks to be less than 10' from supply plenum from the package unit to the additional plenum feeding the chase. 2 - 14" return duct off plenum seem to go straight to return grills. 10 supply vents with 1 closed vent in the kitchen due to flooring. Pausing for Joe S. Area has very weak signal for proper cell phone calls.