My SIL showed me how to do this. Top pic is a new vent that goes to the new central air and heating unit. Bottom pic is of a vent that went to the old heater that no longer is in use. It's been filled in with leveling cement. Cut a piece of wood, put a screw in the center to use as a temporary handle, put wood piece into vent, and screw it in from the top down on the outer edges, then its secured in place, but still an inch deep hole (depth of your base floor) fill that with the leveling mix, it dries and viola! You're ready to put in what ever flooring you desire! That dust is from sanding the new walls... New carpet goes in Tuesday!
