The ornamental design for a filterhousing, as shown and described.
FIG. 1 is an upper perspective view of a filter housing
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines illustrating a structure at the bottom of the article depict the portions of the filter housing that form no part of the claimed design. The broken lines of the vertical plane and the upper housing surface within the outer solid lines represent the boundaries of unclaimed areas of the housing.