System Sensor 2251, 2251T User Manual
D200-80-00 1 I56-1236-03R
2251 and 2251T Intelligent
Photoelectronic Smoke Sensors
INSTALLATION AND MAINTENANCE INSTRUCTIONS
A Division of Pittway
3825 Ohio Avenue, St. Charles, Illinois 60174
1-800-SENSOR2, FAX: 630-377-6495
Before Installing
This sensor must be installed in compliance with the control panel system installation manual. The installation must
meet the requirements of the Authority Having Jurisdiction
(AHJ). Sensors offer maximum performance when installed
in compliance with the National Fire Protection Association
(NFPA); see NFPA 72.
General Description
Model 2251 is a plug-in type smoke sensor that combines a
photoelectronic sensing chamber with addressable-analog
communications. The sensor transmits an analog representation of smoke density over a communication line to a
control panel. Rotary-decade switches are provided for setting the sensor’s address. Two LEDs on the sensor are controlled by the panel to indicate sensor status. An output is
provided for connection to an optional remote LED annunciator (P/N RA400Z). Model 2251T features a fixed temperature (135°F) heat detector.
The 2251 and 2251T require compatible addressable
communications to function properly. Connect these
sensors to listed-compatible control panels only.
Spacing
System Sensor recommends spacing sensors in compliance
with NFPA 72. In low air flow applications with smooth
ceilings, space sensors 30 feet apart. For specific information regarding sensor spacing, placement, and special
applications, refer to NFPA 72 or the System Sensor Guide
For Proper Use of System Smoke Detectors, available at no
charge from System Sensor (P/N I56-407-XX).
Specifications
Operating Voltage Range: 15 to 32 VDC
Standby Current: 300
µA @ 24 VDC (one communication every 5 sec. with LED blink enabled)
Max. Alarm Current (LED on:) 6.5 mA @ 24 VDC
Operating Humidity Range: 10% to 93% Relative Humidity, noncondensing
Operating Temperature Range: 0° to 49°C (32° to 120°F); 2251
Operating Temperature Range: 0° to 38°C (32° to 100°F); 2251T
Heat Sensor: 135°F Fixed Temperature Electronic Thermistor
Height: 1.7 inches (43 mm) installed in B210LP Base
Diameter: 6.1 inches (155 mm) installed in B210LP Base
4.1 inches (104 mm) installed in B501 Base
Weight: 3.6 oz. (102 g)
Additional Bases Available: All 200/500 Series bases are compatible.
Duct Applications: 2251 and 2251T are listed for use in
ducts. See Duct Applications Guide A05-1004-XX for details
on pendant mount applications. Note: These products are
not listed for use inside duct smoke detectors.
Wiring Instructions
All wiring must be installed in compliance with the
National Electrical Code, applicable local codes, and any
special requirements of the Authority Having Jurisdiction.
Proper wire gauges should be used. The installation wires
should be color-coded to limit wiring mistakes and ease
system troubleshooting. Improper connections will prevent
a system from responding properly in the event of a fire.
Remove power from the communication line before
installing sensors.
All wiring must conform to applicable local codes, ordinances, and regulations.
1. Wire the sensor base (supplied separately) per the
wiring diagram, see Figure 1.
2. Set the desired address on the sensor address switches,
see Figure 2.
3. Install the sensor into the sensor base. Push the sensor
into the base while turning it clockwise to secure it in
place.
4. After all sensors have been installed, apply power to the
control unit and activate the communication line.
5. Test the sensor(s) as described in the TESTING section
of this manual.
D200-80-00 2 I56-1236-03R
Dust covers provide limited protection against airborne
dust particles during shipping. Dust covers must be
removed before the sensors can sense smoke. Remove sensors prior to heavy remodeling or construction.
Testing
Before testing, notify the proper authorities that the system
is undergoing maintenance, and will temporarily be out of
service. Disable the system to prevent unwanted alarms.
All sensors must be tested after installation and periodically thereafter. Testing methods must satisfy the Authority
Having Jurisdiction (AHJ). Sensors offer maximum performance when tested and maintained in compliance with
NFPA 72.
The sensor can be tested in the following ways:
A. Functional: Magnet Test (P/N M02-04-01 or M02-09-00)
This sensor can be functionally tested with a test magnet. The test magnet electronically simulates smoke in
the sensing chamber, testing the sensor electronics and
connections to the control panel.
1. Hold the test magnet in the magnet test area as shown
in Figure 3.
2. The sensor should alarm the panel.
Two LEDs on the sensor are controlled by the panel to
indicate sensor status. Coded signals, transmitted
from the panel, can cause the LEDs to blink, latch on,
or latch off. Refer to the control panel technical documentation for sensor LED status operation and
expected delay to alarm.
CAUTION
A78-2461-00
3
2
1
3
2
1
+
–
–
+
UL LISTED COMPATIBLE
CONTROL PANEL
OPTIONAL RETURN LOOP
REMOTE ANNUNCIATOR
+–
B. Smoke Entry: Aerosol Generator (Gemini 501)
The GEMINI model 501 aerosol generator can be used
for smoke entry testing. Set the generator to represent
4%/ft to 5%/ft obscuration as described in the GEMINI
501 manual. Using the bowl shaped applicator, apply
aerosol until the panel alarms.
C. Direct Heat Method (Hair Dryer of 1000-1500 watts)
2251T only
A hair dryer of 1000-1500 watts should be used to test
the thermistors. Direct the heat toward either of the two
thermistors, holding the heat source approximately 12
inches from the detector in order to avoid damaging the
plastic housing. The detector will reset only after it has
had sufficient time to cool. Make sure both thermistors
are tested individually.
A sensor that fails any of these tests should be cleaned as
described under CLEANING, and retested. If the
sensor fails after cleaning, it must be replaced and returned
for repair.
When testing is complete, restore the system to normal
operation and notify the proper authorities that the
system is back in operation.
Figure 1. Wiring diagram:
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