Hi, looking into converting our vented attic into a spray foamed, conditioned attic. We have a new air handler with new ductwork up there.

I see two options:

1) Delete the return ductwork, using the entire attic as the return plenum. But, the attic is full of old romex and some newer HVDC solar wire in conduit. Would this likely be a code violation, i.e. non-plenum rated romex in what is now, technically, a plenum?

2) Add one supply and one return at opposite ends of the attic. Would this avoid the potential code violation mentioned above?

Thanks!!