How To Install Cold Air Return In Wall. Just put two transfer grills on the wall. Running a metal cold air return duct between studs requires knowledge of both hvac systems and the components involved in framing.
I installed these return air pathways in my condo three years ago, and that video shows the one in our guest bedroom, where the positive pressure created by the lack the best use of the perfect balance is in existing homes where you don't have returns in the bedrooms and can't (or don't want to) install.
Installing a return duct in each room where there is a supply vent would be more than feasible but isn't always the best case. How are they going to size a stud cavity or joist space to an individual rooms in the case of any return that is required from a studded wall, why not use the drywall and 2 studs, its the same as using metal ductwork but more. The internal combustion engine relies on air, fuel, and spark to be able to perform, and an enhancement in any of those three areas can make a big difference in power and/or fuel economy. You may have a second building that needs ac, or a refurbished garage or attic that swelters in the summer.