Simplex 4098-9756 — a TrueAlarm addressable duct smoke sensor housing with a supervised multiple-relay control output, supplied with a factory-installed 4098-9714 photoelectric sensor.
The 4098-9756 monitors an HVAC duct for smoke. A sampling tube crossing the duct directs air through the housing to the internal photoelectric sensor, and the exhaust tube returns it. Analog sensor values are transmitted digitally to the fire alarm control unit over IDNet or MAPNET II, where they are tracked against a running average so that dust and component aging are compensated rather than mistaken for smoke. What separates this model from the basic 4098-9755 is the relay output: it drives up to fifteen 4098-9843 Form C relays under panel control — on, off, or override — so fan shutdown and damper control can be commanded manually from the panel or in response to any other system input. That output is supervised, and it is the reason this housing needs a separate fused 24 VDC supply from the fire alarm power supply in addition to the communications pair. The housing includes the 4098-9714 sensor, the exhaust tube and one 4098-9843 relay; the sampling tube is ordered separately to match the duct width.
Specifications
| Device type |
Addressable duct sensor housing with supervised multiple relay output; includes internally mounted 4098-9714 TrueAlarm photoelectric sensor and exhaust tube |
| Data communications |
IDNet or MAPNET II, auto-select, one address per housing |
| Relay control input voltage |
18 to 32 VDC (24 VDC nominal), separate fused 24 VDC from the fire alarm power supply |
| Standby current |
3 mA at 24 VDC |
| Alarm current |
15 mA at 24 VDC, plus 15 mA for each 4098-9843 relay |
| Supervised remote relay output |
4098-9843 relays only, 15 maximum; 500 ft (152 m) maximum; requires 4081-9008 10 kΩ, 1/2 W end-of-line resistor harness |
| 4098-9843 relay contacts |
Single Form C, 7 A at 0.35 PF at 28 VDC and 120 VAC |
| 4098-9843 coil current |
15 mA at 24 VDC |
| Sensor sensitivity range |
0.2% to 3.7% per foot of obscuration, selectable and monitored at the host control panel |
| Air velocity range |
300 to 4,000 ft/min (91 to 1,220 m/min) |
| Pressure differential |
0.015 to 1.55 in. of water (0.381 to 39.37 mm) between intake and exhaust tubes |
| UL listed temperature range |
32°F to 100°F (0°C to 38°C) |
| Operating temperature range |
32°F to 122°F (0°C to 50°C) |
| Storage temperature range |
0°F to 140°F (-18°C to 60°C) |
| Humidity range |
10% to 95% RH, non-condensing |
| Wiring connections |
Terminal blocks, 18 to 12 AWG (0.82 mm² to 3.31 mm²) |
| Housing |
Black ABS base with clear polycarbonate cover; sampling and exhaust tubes are black CPVC |
| Minimum duct size |
8 in. (203 mm) square, or 18 in. (457 mm) diameter |
| Diagnostic LEDs |
Red alarm/trouble LED for sensor status and polling; yellow LED for open or shorted supervised relay control trouble |
| Remote indicator distance |
250 ft (76 m) maximum; remote alarm LED 1.2 mA, test station keyswitch 3.3 mA |
| Compatible control units |
4007ES, 4008, 4010, 4010ES, 4020, 4100, 4100ES, 4100E and 4120. The 2120 CDT is supported for TrueAlarm operation on MAPNET II, but the relay operation is not compatible with the 2120 CDT. |
| Listings |
UL listed to Standard 268A; ULC listed; FM approved; CSFM Listing 3240-0026.241; MEA (NYC) acceptance |
Installation notes
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Separate 24 VDC is mandatory: unlike the 4098-9755, this housing cannot run on communications power alone. The relay control section needs a separate fused 24 VDC feed from the fire alarm power supply.
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End-of-line harness required: the 4081-9008 10 kΩ, 1/2 W end-of-line resistor harness must be fitted at the last relay location to supervise the remote relay coil connection.
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Sampling tube ordered separately: select by overall duct width — 4098-9854 up to 12 in., 4098-9855 for 13 to 23 in., 4098-9856 for 24 to 46 in., 4098-9857 for 46 to 71 in., 4098-9858 for 71 to 95 in. Cut the two smaller tubes 1/2 in. longer than the duct width and the three larger tubes 3 in. longer.
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Orientation: mount the housing at 90° to airflow and do not mount it on the bottom of the duct. Where sampling tubes are not vertical, FDI testing recommends positioning them horizontally in the upper half of the duct to allow for stratification.
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Airflow limits are a design constraint: the location must deliver 300 to 4,000 ft/min and a 0.015 to 1.55 in. water pressure differential, or the housing will not sample correctly.
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Where to place it: downstream of filters to catch filter fires, in return ducts ahead of mixing areas, and upstream of humidifiers and cooling coils. Avoid outside air inlets, return air damper branch ducts and mixing areas, and any point where comfort-control dampers closing would interfere with airflow.
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Relay placement: locate each 4098-9843 within 3 ft (1 m) of the device it controls, per NFPA 72, in its own electrical box.
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Duct detection is supplementary: Johnson Controls states that duct smoke detection is intended to signal smoke in the duct and does not replace open-area smoke detection requirements, and that it must never be regarded as a substitute for the building fire alarm and detection system.
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Testing: the clear cover allows visual inspection, two test ports permit airflow measurement and aerosol injection with the cover in place, and a magnetic test area initiates an alarm at the housing.
Related models
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4098-9755 — the basic duct sensor housing, powered entirely by IDNet/MAPNET II communications with no relay output
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4098-9843 — additional epoxy-encapsulated Form C remote relay; one is included, up to 15 total
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4081-9008 — the 10 kΩ end-of-line resistor harness required to supervise the relay coil connection
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2098-9806 / 2098-9808 — remote test station with keyswitch and status LED, or remote red status/alarm LED, on a single-gang stainless steel plate
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4098-9845 — NEMA 4X weatherproof enclosure for duct housings exposed to the weather (data sheet S4098-0032)
Specifications taken from the Simplex data sheet "TrueAlarm Analog Sensing — Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available with Multiple Relay Control," document S4098-0030-10 (11/2014). Manufacturer specifications are subject to change without notice.
