I claim the ornamental design for a control unit for a water softener, as shown and described.
FIG. 1 is a perspective view of a control unit in accordance with my new design, the broken lines of the control unit are for illustrative purposes only and form no part of the claimed design;
FIG. 2 is a front elevation view of the control unit of FIG. 1;
FIG. 3 is a rear elevation view of the control unit of FIG. 1;
FIG. 4 is a left side elevation view of the control unit of FIG. 1;
FIG. 5 is a right side elevation view of the control unit of FIG. 1;
FIG. 6 is a top view of the control unit of FIG. 1; and,
FIG. 7 is a perspective view of an alternate embodiment of a control unit in accordance with my new design, the broken lines of the control unit are for illustrative purposes only and form no part of the claimed design. This embodiment is similar to the embodiment of FIG. 1 in all respects except that the lower rear portion of the control unit is curved rather than being flat as shown in FIG. 3.