Abstract: A heating control system for automatically controlling the temperature within a space is provided. The heating control system includes a temperature sensor for detecting changes in temperature without the space and in response thereto producing a control signal having a substantially linearly variable potential, the increase or decrease in the variable potential being directly varied in response to changes in temperature without the space. A heat supply includes a control valve adapted to be selectively opened to increase the rate at which heat is supplied to the space and be selectively closed to decrease the rate at which the heat is supplied to the space. A rheostat having a shiftable contact is coupled to the control valve and is disposably controlled thereby to produce a variable reference feedback signal having a substantially linearly variable potential in response to the selective opening and closing of the control valve.