The ornamental design for a heat-system controller, as shown and described.
FIG. 1 is a front perspective view of the heat-system controller of this invention;
FIG. 2 is a front elevational view of the heat-system controller, the back of the heat-system controller being plain and disclaimed;
FIG. 3 is a top edge view of the heat-system controller;
FIG. 4 is a bottom edge view of the heat-system controller;
FIG. 5 is a right-side edge view of the heat-system controller, the left-side edge view of the heat-system controller being a mirror image but lacking the edge view of the small buttons seen in FIG. 4;
FIG. 6 is a back perspective view of the heat-system controller mounted on a stand;
FIG. 7 is a perspective view of the large rotary knob of the heat-system controller of FIGS. 1-5;
FIG. 8 is a front elevational view of the knob;
FIG. 9 is an edge view of the knob, with disclaimed attachment fingers shown in dashed lines; and,
FIG. 10 is a view of another heat-system controller according to the invention that differs from that of FIGS. 1-5 in that the large rotary knob is smooth.