Carrier 50TC*17 Series Service And Maintenance Instructions page 29

wiring terminals. The controller has three LEDs: Power,
Trouble and Alarm. A manual test/reset button is located
on the cover face.
Duct Smoke Sensor
Controller Housing
and Electronics
Conduit Couplings
(supplied by installer)
Fastener
(2X)
Cover Gasket
(ordering option)
Alarm
Fig. 34 − Controller Assembly
Sensor
The sensor (see Fig. 35) includes a plastic housing, a
printed circuit board, a clear plastic cover, a sampling
tube inlet and an exhaust tube. The sampling tube, when
used, and exhaust tube are attached during installation.
The sampling tube varies in length depending on the size
of the rooftop unit. The clear plastic cover permits visual
inspections without having to disassemble the sensor. The
cover attaches to the sensor housing using four captive
screws and forms an airtight chamber around the sensing
electronics. Each sensor includes a harness with an RJ45
terminal for connecting to the controller. Each sensor has
four LEDs: Power, Trouble, Alarm and Dirty. A manual
test/reset button is located on the left side of the housing.
Air is introduced to the duct smoke detector sensor's
sensing chamber through a sampling tube that extends into
the HVAC duct and is directed back into the ventilation
system through a (shorter) exhaust tube. The difference in
air pressure between the two tubes pulls the sampled air
through the sensing chamber. When a sufficient amount of
smoke is detected in the sensing chamber, the sensor
signals an alarm state and the controller automatically
takes the appropriate action to shut down fans and
blowers, change over air handling systems, notify the fire
alarm control panel, etc.
The sensor uses a photoelectric (light scattering principle)
process called differential sensing to prevent gradual
environmental changes from triggering false alarms. A
rapid change in environmental conditions, such as smoke
Controller
Conduit Nuts
(supplied by installer)
Conduit Support Plate
Terminal Block Cover
Controller Cover
Trouble
Power
Test/Reset
Switch
C08208
from a fire, causes the sensor to signal an alarm state but
dust and debris accumulated over time does not.
Exhaust Tube
See Detail A
Intake
Gasket
TSD-CO2
(ordering option)
Plug
Sampling Tube
(ordered separately)
Coupling
Detail A
Magnetic
Test/Reset
Switch
Fig. 35 − Smoke Detector Sensor
For installations using two sensors, the duct smoke
detector does not differentiate which sensor signals an
alarm or trouble condition.
Smoke Detector Locations
Supply Air
The Supply Air smoke detector sensor is located to the
left of the unit's indoor (supply) fan. See Fig. 36. Access
is through the fan access panel. There is no sampling tube
used at this location. The sampling tube inlet extends
through the side plate of the fan housing (into a high
pressure area). The controller is located on a bracket to
the right of the return filter, accessed through the lift−off
filter panel.
SUPPLY AIR
SMOKE
DETECTOR
SENSOR
Fig. 36 − Typical Supply Air Smoke Detector Sensor
29
Duct Smoke Sensor
Exhaust Gasket
Sensor Housing
and Electronics
Cover Gasket
(ordering option)
Sensor Cover
Alarm Power
Trouble Dirty
Location
C08209
C10325