A substrate processing chamber includes a lift actuator that moves a pedestal between a substrate loading position and a substrate processing position. An adjustable seal defines an expandable sealed volume between a bottom surface of the pedestal and a bottom surface of the substrate processing chamber and is moveable between the substrate loading position and the substrate processing position. When the pedestal is in the substrate processing position, the pedestal and the adjustable seal define a first inert volume and a first process volume. When the pedestal is in the substrate loading position, the pedestal and the adjustable seal define a second inert volume and a second process volume. The second inert volume is less than the first inert volume and the second process volume is greater than the first process volume.