[Nealtw]

As I design the framing plan i am working in the HVAC system, so i don't frame in some difficulties.
If I can do it, should I put in wall registers on inside walls? I know on outside walls that's not a good plan.
This HVAC is 99% AC as I have hydronic heat.
It makes sense to do high wall returns for mostly AC action and I am trunking and chasing the main level for that.
That main floor system will have very little intrusion, and the upstairs will get captured in the joist bays as best I can arrange it.
Upstairs I will probably do a mix of high and low returns based on difficulty.
I am looking at vanity and kitchen cab toe kick registers.
I really don't care for the way a floor register looks or catches dirt naturally, but will install them where I have to.

For AC only I would want the both near the top of the wall where the heat is, and far enough apart so you don't suck cold air back into the system .

 

[Nealtw]

No, I am working with the maximum CFM of the air handler and working with the room sizes as a ratio of the whole.

Have you seen where they use a raised ceiling truss to leave room for duct work on the conditioned side of the insulation.