Abstract: A controller, having a microprocessor, a control potentiometer and a monitor interface circuit connected between the microprocessor and the potentiometer, operates to monitor the control potentiometer and monitor interface circuit for failures. The potentiometer along with its wiring terminals and its wiper are monitored for faults. In addition the monitor interface circuit itself is tested so that either a fault in the potentiometer or a fault in the monitor interface circuit will be detected. The monitoring includes three tests performed from time to time. First, voltages across the full potentiometer are measured and compared to a voltage determined at initial installation or commissioning. The measured voltage is compared against limits to detect whether the measured voltage is inside or outside the limits. Second, the voltage across the wiper selected portion of the control potentiometer is measured and compared against a threshold to detect a fault.

Abstract: A modulated burner combustion system that prevents the use of components that were originally not commissioned for use in the system. The present invention uses actuators that contain unique stored identification numbers. When the system is initially configured or commissioned, the unique identification numbers of the actuators are stored in nonvolatile memory in a fuel/air controller. When the system is brought on line, the fuel/air controller microprocessor initially sends false IDs to the actuator together with test control signals to determine if the actuator operates in response to the false identification numbers. If the actuator does operate in response to the false identification numbers, that is an indication that the system has been tampered with and the system is, consequently, shut down. Subsequently, the true identification numbers are transmitted to the actuators with test control signals.