Addressable Duct Sensor Housings with TrueAlarm

TrueAlarm Analog Sensing
UL, ULC Listed*
Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available
with Multiple Relay Control
Compact air duct sensor housing with clear cover to monitor for
the presence of smoke**
Includes factory installed TrueAlarm photoelectric smoke sensor
and features:
• Individual sensor information processed by the host control panel to
determine sensor status
• Digital transmission of analog sensor values via IDNet , 2-wire
• Programmable sensitivity, consistent accuracy, environmental
compensation, status testing, and monitoring of sensor dirt
SKU A4098-9755:
• Basic duct sensor housing (no relay output) powered by IDNet
SKU A4098-9756:
• Duct sensor housing with supervised output for multiple remote relays;
requires separate 24 VDC; includes one relay
• Relay output is under panel control
• At the panel, relay output can be activated manually or in response to a
separate alarm or other input
General features:
UL listed to Standard 268A
Clear cover allows visual inspection
Test ports provide functional smoke testing access with cover in place
Mounts to rectangular ducts or round ducts; minimum size is 8" (203
mm) square or 18" (457 mm) diameter
• Magnetic test feature for alarm initiation at housing
• Optional weatherproof enclosure is available separately (refer to data
sheet AC4098-0032 )
Diagnostic LEDs (on interface board):
Fig 1: Duct Sensor Housing, Front and Bottom View
• Red Alarm/Trouble LED for sensor status and communications polling
• Yellow LED for open or shorted trouble indication of supervised relay
control (A4098-9756 only)
Sampling tubes (ordered separately):
• Available in multiple lengths to match duct size
• Installed and serviced with housing in place
Remote module options (ordered separately):
• Remote red status/alarm LED (A2098-9808)
• Remote test station with LED (A2098-9806)
• 4098-9843 remote relays (refer to Duct Sensor Selection Chart on
page 2)
Fig 2:
Fig 3: A2098-9806
Operation. Autocall compact air duct smoke sensor housings provide
TrueAlarm operation for the detection of smoke in air conditioning or
ventilating ducts. Sampling tubes are installed into the duct allowing air
to be directed to the smoke sensor mounted in the housing.
* Additional listings may be applicable; contact your local Autocall product supplier for the latest status.
AC4098-0030 Rev 10 11/2014
Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available with Multiple Relay
TrueAlarm Sensor Operation
Digital Communication of Analog Sensing. Analog information from the sensor is digitally communicated to the control panel where it is analyzed.
Sensor input is stored and tracked as an average value with an alarm or abnormal condition being determined by comparing the sensor's present
value against its average.
Intelligent Data Evaluation. Monitoring each photoelectric sensor's average value provides a software filtering process that compensates for
environmental factors (dust, dirt, etc.) and component aging, providing an accurate reference for evaluating new activity. The result is a significant
reduction in the probability of false or nuisance alarms caused by shifts in sensitivity, either up or down.
Control Panel Selection. Peak activity per sensor is stored to assist in evaluating specific locations. The alarm set point for each sensor is determined
at the control panel, selectable as the individual application requires.
Sensor Status LED. Each sensor housing's red status LED (located on the electrical interface board) pulses to indicate communications with the
panel. If the control panel determines that a sensor is in alarm, or that it is dirty or has some other type of trouble, the details are annunciated at the
control panel and that sensor housing's status LED will be turned on steadily. During a system alarm, the control panel will control the LEDs such that
an LED indicating a trouble will return to pulsing to help identify any alarmed sensors. (Remote Status/Alarm LEDs track the operation of the sensor
housing LED.)
** Please note that smoke detection in air ducts is intended to provide notification of the presence of smoke in the duct. It is not intended to, and will
not, replace smoke detection requirements for open areas or other non-duct applications.
Photoelectric Sensing
TrueAlarm photoelectric sensors use a stable, pulsed infrared LED light source and a silicon photodiode receiver to provide consistent and accurate
low power smoke sensing.
Typically duct sensor applications require less sensitive settings (such as 2.5% per foot obscuration) due to the ducts being a relative dirty
environment. However, the standard seven levels of TrueAlarm sensor sensitivity are available for each individual sensor, ranging from 0.2% to 3.7%
per foot of smoke obscuration. Sensitivity is selected and monitored at the fire alarm control panel.
Fire Alarm Control Panel Features
Individual smoke sensitivity selection
Sensitivity monitoring that satisfies NFPA 72 sensitivity testing requirements
Peak value logging allows accurate analysis for sensitivity selection
Automatic, once per minute individual sensor calibration check verifies sensor integrity
Automatic environmental compensation
Smoke sensitivity is displayed in percent per foot
Ability to display and print detailed sensor information in plain English language
Relays of model A4098-9756 are under panel control for ON, OFF, or override
Duct Sensor Selection Chart
Table 1: Duct Smoke Sensor Housing with Photoelectric Sensor*
Basic Duct Sensor Housing; operating power is supplied by either
IDNetcommunications (no relay output)
Duct Sensor Housing with supervised multiple relay output, requires
separate 24 VDC fire alarm power and A4081-9008 end-of-line
resistor harness; includes one 4098-9843 relay
4007ES, 4010ES, 4100ES, 4100E.
Relay output is for up to 15 total 4098-9843 Relays (additional
relays are ordered separately)
Table 2: Remote LED Indicator and Test Station, Select One if Required
Page 2
Red LED status indicator on single-gang stainless steel plate
Test Station with keyswitch and red LED status indicator, on single-gang
stainless steel plate; (turning switch to "TEST" initiates alarm for system
Use single gang box, 3" H x 2" W x 2"
D (76 mm x 51 mm x 51 mm)
AC4098-0030 Rev 10 11/2014
Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available with Multiple Relay
Table 3: Epoxy Encapsulated Remote Relay and End-of-Line Resistor
Relay; single Form C (7 A @ 120 VAC); refer to pages 3 and 4 for
Locate relays within 3 ft (1 m) of
A4098-9756 only;
additional relay information; one included with A4098-9756; wiring is 18
device being controlled per NFPA
connect up to 15
AWG (0.82 mm2 ) color coded wire leads
End-of-Line Resistor Harness; 10 kΩ, 1/2 W; (ref. 733-894); required to
At last relay location
supervise remote relay coil connection
* Each duct housing includes an internally mounted model A4098-9714 TrueAlarm photoelectric sensor and an exhaust tube. A correctly sized
sampling tube (ordered per application) is required, refer to chart below.
Sampling Tube Selection Chart, Ordered Separately Per Duct Width, Select One
Overall Duct Width
12" (305 mm)
13" to 23" (330 mm to 584 mm)
24" to 46" (610 mm to 1168 mm)
46" to 71" (1168 mm to 1803 mm)
71" to 95" (1803 mm to 2413 mm)
Page 3
Tube Required
Suggested Cut Length
1/2" (12.7 mm) longer than duct width
1/2" (12.7 mm) longer than duct width
3 in" (76 mm) longer than duct width
3 in" (76 mm) longer than duct width
3 in" (76 mm) longer than duct width
AC4098-0030 Rev 10 11/2014
Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available with Multiple Relay
Duct Sensor Housing Detail Reference
Note: Refer to Installation Instructions 574-776AC for additional installation detail and maintenance information.
Fig 4: Duct Sensor Housing Detail Reference
* A4098-9756 only.
Page 4
AC4098-0030 Rev 10 11/2014
Addressable Duct Sensor Housings with TrueAlarm Photoelectric Sensor; Available with Multiple Relay
Duct Sensor Location Reference
Duct Sensor Location Considerations:
1. Proper duct smoke detection location must ensure adequate airflow within the duct housing.
2. Duct air velocity rating is 300 to 4000 ft/min (91 to 1220 m/min). Pressure differential between intake and exhaust tubes is required to be between
0.015 to 1.55 inches of water (0.381 to 39.37 mm).
3. Ensure accessibility for test and service.
4. Proper Locations: downstream side of filters to detect fires in the filters; in return ducts, ahead of mixing areas; upstream of air humidifier and
cooling coil.
5. Other locations and orientations may be required for proper duct smoke detection depending on duct access, system design, and duct airflow
testing. Contact your local Autocall product supplier for assistance.
Locations to Avoid:
1. Where dampers closed for comfort control would interfere with airflow.
2. Next to outside air inlets (unless the intent is to monitor smoke entry from that area).
3. In return air damper branch ducts and mixing areas where airflow may be restricted.
Additional Information. Refer to NFPA 90A, Standard for the Installation of Air Conditioning and Ventilating Systems; NFPA 72, the National Fire
Alarm and Signaling Code; and the NEMA Guide for Proper Use of Smoke Detectors in Duct Applications, and Installation Instructions 574-776AC.
Page 5
AC4098-0030 Rev 10 11/2014
Table 4: General Mechanical and Environmental
Air Velocity Range (linear ft/min)
Sensor Sensitivity Range
UL Listed Temperature Range
Operating Temperature Range
Storage Temperature Range
Humidity Range
300 to 4000 ft/min (91 to 1220 m/min)
0.2% to 3.7% per foot of obscuration, selectable at host control panel
32° F to 100° F (0° C to 38° C)
32° F to 122° F (0° C to 50° C)
0° F to 140° F (-18° C to 60° C)
10% to 95% RH, non-condensing
Wiring Connections
Terminal blocks, 18 to 12 AWG (0.82 mm to 3.31 mm )
Housing Color and Material
Sampling and Exhaust Tube Material
Black ABS base with clear polycarbonate cover
Black CPVC, custom extrusion; sampling tubes are pre-drilled
Table 5: Remote Status/Alarm LED and Test Station with Remote Status/Alarm LED
Remote Alarm LED Current
Test Station Keyswitch Current
Remote Alarm LED and Test Station Distance
1.2 mA, no impact to 24 VDC alarm current (A2098-9808 or A2098-9806)
3.3 mA, no impact to 24 VDC alarm current (A2098-9806)
250 ft (76 m) maximum
Table 6: Addressable Operation
IDNet communications, auto-select, one address per housing; provides operating power to
model A4098-9755
Data Communications
Table 7: SKU A4098-9756 with Supervised Multiple Relay Control, Requires Separate Fused 24 VDC from Fire Alarm Power Supply
Input Voltage
Standby Current
Alarm Current
Supervised Remote Relay Control Output
18-32 VDC (24 VDC nominal)
3 mA @ 24 VDC
15 mA @ 24 VDC; add 15 mA for each 4098-9843 relay
For use with 4098-9843 relay only, quantity of 15 maximum; distance of 500 ft (152 m)
maximum; requires A4081-9008 (ref. 733-894) 10 kΩ, 1/2 W end-of-line resistor
Table 8: Relay Output Ratings, Single Form C, use with Model Only
Coil Current
Relay Contacts
Location Distance
15 mA @ 24 VDC, up to 15 maximum per relay control output
7 A at 0.35 PF @ 28 VDC & 120 VAC; 250 μA @ 5 VDC
500 ft (152 m) maximum to relay coils; locate relays within 3 ft (1 m) of device being
controlled per NFPA 72
© 2017 Johnson Controls. All rights reserved. All specifications and other information shown were current as of document revision and are subject to change without notice.
Additional listings may be applicable, contact your local Autocall product supplier for the latest status. Listings and approvals under Tyco Fire & Security GmbH, and the
product names listed in this material are marks and/or registered marks. Unauthorized use is strictly prohibited. NFPA 72 and National Fire Alarm Code are registered
trademarks of the National Fire Protection Association (NFPA).
AC4098-0030 Rev 10 11/2014
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