The Saf-T-Duct Dryer Outlet Box from Builder's Best finishes off dryer vent rough-ins and easily adds or recaptures space in the wall behind your dryer for venting. The unit can be used in-wall (prior to drywall) or on-wall (after drywall is installed). The standard 4 in. round connections allow for the best airflow and connect easier than ovals.Dundas Jafine 28 in. to 45 in. Adjustable,- The Home Depot,Be aware that other parts of the dryer vent could affect the flow. The total number of elbows and the total length of your vent may pose a bigger problem than this dryer vent. 28 in. to 45 in. Adjustable Space Saver Aluminum Dryer Vent Duct with Straight Outlet - page 22021 Cost to Install Dryer Vent | Replace or Reroute Duct,,Most homeowners spend between $80 and $200 to install or replace a dryer vent, including labor and materials. Total project price can be as much as $1,000, depending on factors like placement, material quality, and installation difficulty.Costs should be the same whether you are dealing with a standalone washer and dryer set or a stackable washer/dryer unit.