22
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 process called differential sensing to prevent
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.
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.
For installations using two sensors, the duct smoke detector
does not differentiate which sensor signals an alarm or trouble
condition.
Fig. 36 — Smoke Detector Sensor
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. 37). Access is through
the fan access panel. There is no sampling tube used at this lo-
cation. 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.
Fig. 37 — Typical Supply Air Smoke Detector Sensor
Location
RETURN AIR SMOKE DETECTOR SENSOR WITHOUT
ECONOMIZER
The sampling tube is located across the return air opening on
the unit basepan (see Fig. 38). The holes in the sampling tube
face downward, into the return air stream. The sampling tube is
connected through tubing to the return air sensor that is mount-
ed on a bracket high on the partition between return filter and
controller location. (This sensor is shipped in a flat-mounting
location. Installation requires that this sensor be relocated to its
operating location and the tubing to the sampling tube be con-
nected. See installation steps in “Completing Installation of
Return Air Smoke Detector” section.)
Fig. 38 — Typical Return Air Smoke Detector Location
RETURN AIR SMOKE DETECTOR SENSOR WITH
ECONOMIZER
The sampling tube is inserted through the side plates of the
economizer housing, placing it across the return air opening on
the unit basepan (see Fig. 39). The holes in the sampling tube
face downward, into the return air stream. The sampling tube is
connected using tubing to the return air sensor mounted on a
bracket high on the partition between return filter and control-
ler location. The sensor is shipped in a flat-mounting location.
Installation requires the sensor be relocated to its operating lo-
cation and the tubing to the sampling tube be connected. See
installation steps in “Completing Installation of Return Air
Smoke Detector” section.
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)
SUPPLY AIR
SMOKE DETECTOR
*RA detector must be moved from shipping
position to operating position by installer.
RETURN AIR DETECTOR
SAMPLING TUBE
RETURN AIR
DETECTOR MODULE
(Shipping position
shown)*
CONTROLLER
MODULE
Summary of Contents for Preferred 581J04-14
Page 36: ...36 Fig 60 Integrated Gas Control IGC Board RED LED STATUS ...
Page 44: ...44 Fig 65 RTU Open Overlay for Economizer Wiring ...
Page 45: ...45 Fig 66 VFD Overlay for W2770 Controller Wiring ...
Page 100: ...100 Fig F 581J 08 09 YAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 101: ...101 Fig G 581J 11YAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 102: ...102 Fig H 581J 12 YAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 103: ...103 Fig I 581J 04 06 YAC Power Diagram 208 230 1 60 APPENDIX D WIRING DIAGRAMS ...
Page 104: ...104 Fig J 581J 04 06 YAC Power Diagram 208 230 3 60 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 105: ...105 Fig K 581J 04 06 YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 108: ...108 Fig N 581J 07 12A B C YAC Power Diagram 208 230 3 60 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 109: ...109 Fig O 581J 07 12A B C YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 110: ...110 Fig P 581J 08 09 YAC Power Diagram 230 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 111: ...111 Fig Q 581J 08 09 YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 112: ...112 Fig R 581J 11 YAC Power Diagram 208 230 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 113: ...113 Fig S 581J 11 YAC Power Diagram 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 114: ...114 Fig T 581J 11 YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 115: ...115 Fig U 581J 12 YAC Power Diagram 230 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 116: ...116 Fig V 581J 12 YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 117: ...117 Fig W 581J 14 YAC Control Diagram 208 230 3 60 460 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 118: ...118 Fig X 581J 14 YAC Power Diagram 208 230 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 119: ...119 Fig Y 581J 14 YAC Power Diagram 460 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 120: ...120 Fig Z 581J 14 YAC Power Diagram 575 3 60 APPENDIX D WIRING DIAGRAMS ...
Page 143: ...143 Fig AW RTU Open Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
