The RP-2001 is compatible with System Sensor's i3 detectors which are conventional smoke detectors that can transmit a maintenance trouble signal to the FACP indicating the need for cleaning and a supervisory 'freeze' signal when the ambient temperature falls below the detector rating of approximately 45°F (7.22°C). 4 Notifier Device Compatibility Document — P/N 15378:BR 10/15/2018 Control Panel Circuit Specification LISTED for 9th Edition FireWarden-50/E/C (NZM-100) Initiating Device Circuit Voltage: 18.75 - 26.1 VDC Compatibility Identifier: "A" The RP-2001 is compatible with System Sensor's i3 detectors which are conventional smoke detectors that can transmit a maintenance trouble signal to the FACP indicating the need for cleaning and a supervisory 'freeze' signal when the ambient temperature falls below the detector rating of approximately 45°F (7.22°C).