Replacing your Notifier FSD-751PL with a System Sensor DNR is a feasible option. The System Sensor DNR is compatible with many existing duct smoke detector installations, including those originally fitted with the Notifier FSD-751PL. The DNR offers intelligent non-relay photoelectric sensing technology, ensuring reliable detection of smoke particles in low-flow air environments. It’s a straightforward swap-out process, but it’s crucial to ensure proper wiring and configuration according to the manufacturer’s guidelines to maintain system integrity and functionality. If you have any specific concerns or questions during the replacement process, feel free to reach out for assistance!