31
housing with a single captive screw for easy access to the
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
CONDUIT NUTS
(SUPPLIED BY INSTALLER)
CONDUIT SUPPORT PLATE
TERMINAL BLOCK COVER
COVER GASKET
(ORDERING OPTION)
CONTROLLER
COVER
FASTENER (2X)
CONDUIT COUPLINGS
(SUPPLIED BY INSTALLER)
CONTROLLER HOUSING
AND ELECTRONICS
ALARM
TROUBLE
POWER
TEST/RESET
SWITCH
C08208
Fig. 37 -- Controller Assembly
Sensor
The sensor includes a plastic housing, a printed circuit
board, a clear plastic cover, a sampling tube inlet and an
exhaust tube. See Fig. 38. 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
preventing gradual
environmental changes from triggering false alarms. A
rapid change in environmental conditions, such as smoke
from a fire, causes the sensor to signal an alarm state, but
dust and debris accumulated over time does not.
SEE DETAIL
A
DETAIL
A
PLUG
SAMPLING TUBE
(ORDERED SEPARATELY)
COUPLING
MAGNETIC
TEST/RESET
SWITCH
ALARM
TROUBLE
POWER
DIRTY
SENSOR
COVER
COVER GASKET
(ORDERING OPTION)
SENSOR HOUSING
AND ELECTRONICS
EXHAUST GASKET
EXHAUST TUBE
DUCT SMOKE SENSOR
INTAKE
GASKET
TSD-CO2
(ORDERING OPTION)
C08209
Fig. 38 -- 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. 39. 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 control module is mounted in the left
side of the control box, accessed by opening the Control
Box access door.
SUPPLY AIR
SMOKE
DETECTOR
SENSOR
C10325
Fig. 39 -- Typical Supply Air Smoke Detector Sensor
Location
48H
C
Summary of Contents for 48HC D17 Series
Page 77: ...77 APPENDIX IV WIRING DIAGRAMS C12616 Fig 77 48HC D17 D28 Power Diagram 208 230 3 60 48HC...
Page 78: ...78 APPENDIX IV WIRING DIAGRAMS C12617 Fig 78 48HC D17 D28 Power Diagram 460 3 60 48HC...
Page 79: ...79 APPENDIX IV WIRING DIAGRAMS C12618 Fig 79 48HC D17 D28 Power Diagram 575 3 60 48HC...
Page 86: ...86 APPENDIX IV WIRING DIAGRAMS C13767 Fig 86 RTU OPEN Wiring Diagram 48HC...
Page 87: ...87 APPENDIX IV WIRING DIAGRAMS C13768 Fig 87 RTU OPEN Wiring Diagram with Humidi MiZer 48HC...
