INSTALLATION AND MAINTENANCE INSTRUCTIONS
2112/24AT
Photoelectronic Smoke Detector with
Fixed Heat and Integral Temp-3 Sounder
Figure 1. Wiring diagram for the 2112/24AT detector:
IMPORTANT: OBSERVE POLARITY
As with all sounder models, polarity must be observed on the power connections.
+
POWER
TO
DETECTORS
–
+
P
W
+
R
–
A
UL LISTED
COMPATIBLE
CONTROL
PANEL
INITIATING
LOOP
ALARM
CONTACT
A
NOT USED
OPTIONAL CLASS A WIRING
P
+
W
+
R
–
A
ALARM
CONTACT
A
NOT USED
3825 Ohio Avenue, St. Charles, Illinois 60174
1-800-SENSOR2, FAX: 630-377-6495
EOL POWER
SUPERVISION
RELAY (SHOWN
ENERGIZED)
A77-716 12/24V
EOL RESISTOR
SPECIFIED BY
PANEL
MANUFACTURER
A78-2336-14
Specifications
Diameter: 5.5 inches (140 mm)
Height (including mounting bracket): 2.05 inches (52 mm)
Weight: 7.5 oz. (210 g)
Operating Temperature Range: 32° to 100°F (0° to 38°C)
Operating Humidity Range: 10% to 93% Relative Humidity, Noncondensing
Latching Alarm: Reset by momentary power interruption
Audible Signal: 85 dBA minimum when in alarm or with supply polarity reversed
Heat Sensor: 135°F Fixed Temperature Electronic Thermistor
Electrical Ratings
System Voltage (nominal): 12 or 24 VDC
Minimum: 10 VDC
Maximum: 35 VDC
Maximum Ripple Voltage: 30% of nom. Voltage (peak to peak)
Standby Current: 50 µA maximum
Alarm Current: 49 mA typical, 60 mA max. at 12V
57 mA typical, 65 mA max. at 24V
Reset Voltage: 0.8 VDC minimum
Reset Time: 1.0 second maximum
Start-up Time: 30 seconds maximum (after 60 sec. reset)
EOL Relay: A77-716B, 12/24 VDC
Alarm Initiation
Contact Rating, Resistive Load: 1A @ 30 VDC
Special Considerations: Due to the built-in temporal pattern, use this detector only with a non-coded
power supply.
Before Installing
Please thoroughly read the System Sensor manual I56-407,
NOTICE: This manual shall be left with the owner/user of
this equipment.
Guide for Proper Use of System Smoke Detectors, which provides detailed information on detector spacing, placement,
zoning, wiring, and special applications. Copies of this
manual are available at no charge from System Sensor.
D200-82-00 1 I56-1237-01R
IMPORTANT: This detector must be tested and maintained
following NFPA 72 requirements. The detector should be
cleaned at least once a year.
Figure 2. Surface mounting of 2112/24AT smoke
detector on 31/2-inch and 4-inch octagonal box:
A78-2563-05
General Description
Model 2112/24AT is a 4-wire photoelectronic smoke detector that uses a state-of-the-art optical sensing chamber.
The detector also provides restorable, 135˚F fixed-temperature heat detection. The unit has a heat detection unit that
is integrated with the photoelectronic sensor.
In addition, a piezoelectric horn in each detector produces
an interrupted, 85 dBA tone when the individual detector
alarms or when the supply voltage polarity is reversed.
NOTE: In order for all detectors on a loop to sound when
the panel alarms, the panel must reverse the supply voltage
polarity to that loop upon alarm. For panels that do not reverse the polarity during alarm, a reversing relay, such as
System Sensor’s RR-2, must be used. The RR-2 is designed
to allow all the detectors in the same loop to sound when
one of the detectors goes into alarm. Some panels may require the use of programmable outputs. Refer to System
Sensor literature for further information on the RR-2.
Installation of these detectors is simplified by the use of a
mounting bracket and a plug-in screw terminal block that
can be prewired to the system, allowing the detector to be
easily installed or removed for cleaning. The detector’s
sensitivity can be tested in place using the MOD400R Test
Module.
An LED on the detector provides a local visual indication of
the detector’s status. If power is applied to the detector and
it is functioning normally in standby within the listed sensitivity range, the status LED blinks every ten seconds. The
LED also latches on in alarm.
Figure 3. 2112/24AT smoke detector mounting bracket:
TAMPER SLOT
(DEPRESS TAB TO
REMOVE DETECTOR)
If the LED stops blinking, the unit should be removed for
maintenance and inspection.
Mounting
Each 2112/24AT detector is supplied with a mounting
bracket that permits the detector to be mounted:
1. To a single gang box, or
2. Directly to a 3-1/2 inch or 4 inch octagonal box, or
3. To a 4 inch square electrical box by using a plaster ring.
4. Directly to the ceiling using drywall anchors, if permitted by local codes and/or the authority having jurisdiction.
Tamper-resistant Feature
This detector includes a tamper-resistant feature that prevents its removal from the bracket without the use of a tool.
To make the detector tamper-resistant, remove the smaller
tab by breaking it at the scribed line on the tamper resistant
tab on the detector mounting bracket (see Figure 3), then
install the detector. To remove the detector from the bracket
once it has been made tamper resistant, use a small screwdriver to depress the tamper-resistant tab, located in the
slot on the mounting bracket, and turn the detector counterclockwise.
Wiring Installation Guidelines
All wiring must be installed in compliance with the National Electrical Code, applicable local codes, and any special requirements of the local authority having jurisdiction.
Proper wire gauges should be used. The conductors used to
connect smoke detectors to control panels and accessory
devices should be color-coded to reduce the likelihood of
wiring errors. Improper connections can prevent a system
from responding properly in the event of a fire.
The screw terminal block accepts 14 – 22 gauge wire. For
best system performance, all wiring should be installed in
separate grounded conduit. Do not mix fire system wiring
in the same conduit as any other electrical wiring. Twisted
pair may be used to provide additional protection against
electrical interference.
Smoke detectors and alarm system control panels have
specifications for allowable loop resistance. Consult the
control panel specifications for the total loop resistance allowed for the control panel being used before wiring the
detector loops.
TAMPER RESISTANT TAB
(CUT OFF SMALL TAB TO
ACTIVATE TAMPER-RESIST
FEATURE)
ALIGNMENT
ARROWS
A78-2333-01
D200-82-00 2 I56-1237-01R
Wire connections are made by stripping about 1/4 inch of
insulation from the end of the feed wire, inserting the wire
into the appropriate terminal, and tightening the screw to
secure the wire in place.
Installation
WARNING
Remove power from the control unit or initiating device circuits before installing detectors.
1. Wire the plug-in screw terminal block per Figure 1 and
plug the terminal block into the detector.
2. Align the arrows on the detector with the arrows on the
mounting bracket.
3. Turn the detector clockwise in the mounting bracket until it clicks into place.
4. After all detectors have been installed, apply power to
the control unit or initiating device circuits.
5. Test the detector as described in TESTING.
6. Reset the detector at the system control panel.
7. Notify the proper authorities the system is in operation.
2. Press and hold the recessed test switch with a 0.18
inch maximum diameter tool such as an allen wrench
or small screwdriver.
3. The detector’s LED should light within 5 seconds.
B. Test Module (System Sensor Model No. MOD400R).
The MOD400R test module can be used with a DMM or
analog voltmeter to check the detector sensitivity as described in the test module’s manual.
C. Smoke Entry Test
Hold a smoldering punk stick or cotton wick at the side
of the detector and gently blow smoke through the detector until the unit alarms.
D. Direct Heat Method (Hair dryer of 1000-1500 watts)
Direct the heat toward either of the side thermistors.
Hold the heat source about 12 inches from the detector
in order to avoid damage to the plastic. The detector will
reset only after it has had sufficient time to cool and the
power source has been momentarily interrupted.
Both smoke and heat detection testing are recommended
for verifying system protection capability.
CAUTION
Dust covers are an effective way to limit the entry of dust
into smoke detector sensing chambers. However, they may
not completely prevent airborne dust particles from entering the detector. Therefore, System Sensor recommends the
removal of detectors before beginning construction or other
dust producing activity. Be sure to remove dust covers from
any sensors that were left in place during construction as
part of returning the system to service.
Testing
NOTE: Before testing, notify the proper authorities that
the smoke detector system is undergoing maintenance and will be temporarily out of service. Disable the zone or system undergoing maintenance
to prevent unwanted alarms.
Detectors must be tested after installation and following
periodic maintenance. Test the 2112/24AT as follows:
A. Test Switch
1. A recessed test switch is located on the detector housing (See Figure 4).
A detector that fails to activate with any of the above tests
should first be cleaned as outlined in MAINTENANCE. If
the detector still fails to activate, return it for repair.
Notify the proper authorities the system is back in
operation.
Maintenance
NOTE: Before removing the detector, notify the proper au-
thorities that the smoke detector system is undergoing maintenance and will be temporarily out of
service. Disable the zone or system undergoing
maintenance to prevent unwanted alarms.
NOTE: Before removing the detector cover, note the posi-
tion of the thermistors. Make sure the thermistors
are not bent over when the housing is replaced.
1. Remove the detector housing by gently prying the four
housing tabs on the bottom of the base with a smallbladed screwdriver and pull the housing from the base.
Use caution to avoid damaging the thermistors.
Figure 4. Top and side views showing position of test switch:
LED
PUSH RECESSED
SWITCH WITH A
TEST MODULE
SOCKET
D200-82-00 3 I56-1237-01R
RECESSED TEST
SWITCH
0.18″ MAX. DIAMETER TOOL
A78-2564-00
3. Remove screen assembly, pulling straight out (please
see Figure 5).
4. Remove the sensing chamber cover.
5. Clean the sensing chamber by vacuuming or blowing
out dust and particles.
6. Replace the sensing chamber cover, aligning the arrow
on the cover top with the arrow on the printed circuit
board.
7. Replace the screen by placing the screen assembly over
the sensing chamber cover and twisting until it snaps
into place.
8. Replace the housing by aligning the three triangular
slots on the base with their counterparts on the housing. Gently press the housing until it locks in place.
Check to make sure that the thermistors are in the upright position.
9. Reinstall the detector.
10. Notify the proper authorities that the system is back in
operation.
Figure 5. Removal of cover and screen for cleaning: 2. Vacuum the screen carefully without removing it.
REMOVABLE
HOUSING
REMOVABLE
SCREEN
SENSING
CHAMBER
COVER
SENSING
CHAMBER
BASE
A78-2565-10
Please refer to insert for the Limitations of Fire Alarm Systems
Three-Year Limited Warranty
System Sensor warrants its enclosed smoke detector to be free from defects in materials and workmanship under normal use and service for a
period of three years from date of manufacture. System Sensor makes no
other express warranty for this smoke detector. No agent, representative,
dealer, or employee of the Company has the authority to increase or alter
the obligations or limitations of this Warranty. The Company’s obligation
of this Warranty shall be limited to the repair or replacement of any part of
the smoke detector which is found to be defective in materials or workmanship under normal use and service during the three year period commencing with the date of manufacture. After phoning System Sensor’s toll
free number 800-SENSOR2 (736-7672) for a Return Authorization number,
send defective units postage prepaid to: System Sensor, Repair Depart-
D200-82-00 4 I56-1237-01R
ment, RA #__________, 3825 Ohio Avenue, St. Charles, IL 60174. Please
include a note describing the malfunction and suspected cause of failure.
The Company shall not be obligated to repair or replace units which are
found to be defective because of damage, unreasonable use, modifications, or alterations occurring after the date of manufacture. In no case
shall the Company be liable for any consequential or incidental damages
for breach of this or any other Warranty, expressed or implied whatsoever,
even if the loss or damage is caused by the Company’s negligence or fault.
Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to
you. This Warranty gives you specific legal rights, and you may also have
other rights which vary from state to state.
© System Sensor 1998
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