Here is what the techs will be dealing with next. The photo below shows the upstairs 12" supply on the far left, seperate ducted 8" MstBR return in the middle and 12" upstairs return on the right. You can barely see in the 12" return on the right that there is a 10" first floor ceiling return cut into it and pookied just above the sheetrock. Second photo shows the backside of these ducts, so right is left, left is right. Any ideas on the best way to tie the 8" and the 12" return together into the plenum? is as drawn functional? Comments?
This photo shows the wall to the right of the last photo. These are all returns needing to be ducted into/with the previous 12" above, and on-top of the downflow AH. The first two 7" holes will be run down stud cavaties and become toe kick returns. The 8" hole further to the right, is from a ceiling return that will be ducted through a boxed soffit into the TJI's of the great room. I know this seems convuluted but this build and its many beams and perpendicular intersecting joist, have left no alternatives in a multi return design. This design was crunched by several techs and a structural engineer. It is what it is. Return capacity is slightly larger than supply according to the techs.
The plan is to use a long correctly sized box to catch all the returns below and connect them to the return plenum below the 12" in the previous photo. Comments?