Abstract: Control apparatus for automatically enabling and disabling the thermostatic control of a plurality of building temperature control units. A programmable timer is provided for adapting the control apparatus to a desired building use schedule. A manually operable override switch is also provided to allow for temperature control during unscheduled building occupancies and additional circuitry automatically disables the override switch to prevent the control apparatus from remaining overridden for an extended period of time in the event the override switch is not reset. A temperature limit switch is further provided to return the temperature control units to thermostatic control if the building temperature drifts outside a predetermined range during periods of disablement.