Abstract: A control arrangement for a heating system including a furnace having a fuel-fired burner apparatus and a vent stack with a motor driven damper plate pivotally mounted within the stack, includes a stack damper control circuit including first and second limit switches which permit energization of a drive motor in response to a request for heat, premitting the damper plate to be driven to an open position, and for energizing an interlock switch which prepares an energizing path for fuel supply valves of the system, the first limit switch being operated when the damper plate approaches the open position to complete the energizing path for the fuel supply valves prepared by the interlock switch, and the second limit switch deenergizing the motor when the damper plate is driven to the fully open position. The motor is reenergized at the end of the heating cycle to drive the damper plate to the closed position, and the second limit switch deenergizes the motor when the damper plate reaches the closed position.

Abstract: A method and control arrangement for a heating system including solar heating apparatus and a conventional fuel-fired heating apparatus wherein heat load of the heating system and solar heating source capability are compared, and the heating system is switched to solar heating whenever the heating capability of the solar heating apparatus exceeds the heat load of the system, the heating system being switched to the conventional heating apparatus only when the heat load exceeds the heating capability of the solar heating apparatus.

Abstract: A stack damper control arrangement for use in a heating system including a furnace having a fuel-fired burner apparatus and a vent stack for conducting combustion products away from the burner apparatus and a damper plate pivotally mounted within the stack and movable between a fully open and a fully closed position, includes a reversible drive motor which is energizable in response to a request for heat to drive the damper plate to the open position, a first limit switch operated when the damper plate reaches the open position to effect the deenergization of the motor, the motor being reenergized at the end of the heating cycle to drive the damper plate to the closed position, and a second limit switch operated when the damper plate reaches the closed position to effect the deenergization of the motor.

Abstract: An anti-reset windup proportional plus integral controller connectable in a proportional control loop of a process control system includes a proportional amplifier circuit and an integrating amplifier circuit responsive to a command signal to provide proportional and integral signals, respectively, which are summed by a summing amplifier to provide a modified command signal having a proportional and an integral component. A signal comparator means compares the modified command with a pair of reference signals which define an output range for said summing amplifier and disables the integrating amplifier circuit, permitting the integrating amplifier circuit to unwind whenever the modified command signal is not within the output range.

Abstract: A heating system has means for directing heat only to a portion of a medium for storing heat which portion is at a temperature below that to which heating means then heats the medium. The system then functions to store heat in the medium during periods of less-than-maximum heating of the medium without degrading the temperature of a higher-temperature portion of the medium. The system has particular utility with a solar heat collector from which the available heat varies with the intensity of the solar energy. Heat is then collected in the portion of the medium during periods of marginal solar energy intensity without degrading the higher temperature of another portion of the medium heated to a higher temperature during a prior period of greater solar energy intensity. In a specific embodiment the system has three compartments for separating a fluid heat-storing medium into portions, a pump supplying the fluid to a solar heat collector, and a pump supplying the fluid to a heat exchanger for heating a house.