Ideas for duct work

[Tfue]

I just recently bought a house with a 30x40 shop. It was one open shop but I've built walls inside to make separate rooms. The shop has a goodman air handler with a heat pump and 10k heat strips. It's currently set up with a simple duct blowing out from the top.

This worked ok, until I built the rooms inside. Now only the rooms nearest the air handler are getting warm. I'm planning on adding duct work to each room so I get more even heat/ac throughout. Any ideas how to do this without calling someone out? I was thinking a plenum in the attic with flex ran to the rooms should work. Would this be ok?

 

[DeltaWye]

I'm not an expert but it seems to me that anything you do will be an improvement over what you have, so you probably don't need to be too scientific. If you made a sketch showing the rough sizes of the rooms and the location, orientation and CFM of the AHU, you'd probably get some decent suggestions for how to go about it. I imagine you'd need to fabricate or find a shop that will make you a few transitions to make it work well.

 

[Stuff]

Also look at return air ducts if possible. Maybe just a few wall openings allowing floor air to circulate.