The System Sensor D4120 is an industrial-grade 4-wire photoelectric duct smoke detector designed for high-performance smoke detection in HVAC air handling systems. This InnovairFlex duct smoke detector operates across a wide air velocity range of 100 to 4,000 feet per minute, making it suitable for both low-flow and high-volume applications. It features a versatile pivoting housing that accommodates square or rectangular footprints and mounts easily to round or rectangular ductwork. Engineered with a photoelectric sensor head, the unit provides superior false alarm immunity and simplified maintenance via its plug-in design. The D4120 duct smoke detector is a direct replacement for legacy models 70-540000-002, 70-600000-054, and 70-600000-157, as well as the DH100ACDCLP. Equipped with two DPDT relay contacts and a dual 24Vac/dc or 120Vac power supply, this detector supports multi-fan shutdown through a patented interconnect feature that allows for up to 50 synchronized units. Its tool-free sampling tube installation and improved 3/4-inch conduit knockout ensure a streamlined HVAC duct smoke detector installation for field contractors. Key Benefits Multi-Voltage Compatibility: Operates on 24V AC/DC or 120V AC, providing flexibility for various control circuit requirements. Broad Environmental Range: Performance-tested for temperatures from -4°F to 158°F and 0% to 95% non-condensing humidity. Advanced Interconnect Logic: Supports interconnection of up to 50 detectors for comprehensive system shutdown upon smoke detection. Streamlined Maintenance: Features a front-accessible Test/Reset button and a plug-in sensor head that can be serviced without removing the entire housing. Short Circuit Protection: Built-in safeguards protect internal components from operator wiring errors during commissioning. Common Questions How do I wire the D4120 for fan shutdown? Use the DPDT Form-C auxiliary relay contacts to break the starter or control circuit of the air handler. Ensure polarity is maintained if using the interconnect feature for multiple fans. Do I need a specific sampling tube for my duct width? Yes, the sampling tube must be ordered separately based on the duct's width to ensure the sensor receives adequate airflow for accurate detection. Can I use a secondary sensor with this power board? The D4120 features 2:1 sensor-to-power capability, allowing the master power board to monitor a second sensor (Model D4S) for supply and return side coverage. Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
