The ornamental design for a ventilationunit, as shown and described.
FIG. 1 is a perspective view of a ventilation unit showing our new design, it being understood that the unit is located in a environmental space to be ventilated;
FIG. 2 is a front elevation view of the ventilation unit thereof of FIG. 1;
FIG. 3 is a rear elevation view of the ventilation unit thereof of FIG. 1;
FIG. 4 is a right side elevation view of the ventilation unit thereof of FIG. 1;
FIG. 5 is a left side elevation view of the ventilation unit thereof of FIG. 1;
FIG. 6 is a top plan view of the ventilation unit thereof of FIG. 1;
FIG. 7 is a bottom view of the ventilation unit thereof of FIG. 1;
FIG. 8 is an exploded right side elevation view of the ventilation unit thereof of FIG. 1 showing a removable cover displaced from a base, as indicated by the broken lines, for accessing internal components of the ventilation unit; and,
FIG. 9 is a plan view of the ventilation unit of our new design being operated, wherein the dashed lines of a crawl space environment and arrows indicating an air flow provided by the ventilation unit indicate a typical environment of the ventilation unit and are not a part of the claimed invention.