There was no heat to the upstairs, so I had a closet built for a place to install a furnace. (I wish I had installed a furnace unit that also included air conditioning. The upstairs get much hotter than the down stairs. Also the ducts should be larger with another vent in each room. The vents make too much noise when they furnace comes on. This something I will have to have redone eventually. Another lesson learned!)
My favorite drywaller textured the added wall to match the other walls. The duct work for the furnace is in the attic, and the wiring and gas line was run up an old chimney space of the fireplace that was removed long ago. At the same time, I also had new wiring installed and now all the rooms upstairs are on different circuits.