Smoke Detector Locations - Carrier 48JCH 04-06 Series Service And Maintenance Instructions

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 sam-
pled 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 sam-
pled 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.
Duct Smoke Sensor
Exhaust Tube
See
Detail A
Intake
Gasket
TSD-CO2
(Ordering Option)
Plug
Sampling Tube
(Covered Separately)
Coupling
Detail A
Magnetic
Test/Reset
Switch
Fig. 31 — Smoke Detector Sensor

Smoke Detector Locations

SUPPLY AIR
The supply air smoke detector sensor is located to the right of
the unit's indoor (supply) fan (see Fig. 32). Access is through
the fan access panel. The sampling tube inlet extends through
the fan deck (into a high pressure area). The controller is locat-
ed on a bracket to the right of the return filter, accessed through
the lift-off filter panel.
Exhaust Gasket
Sensor Housing and Electronics
Cover Gasket
(Ordering Option)
Sensor
Cover
Alarm Power
Trouble Dirty
Supply Air
Smoke Detector
Fig. 32 — Typical Supply Air Smoke Detector Sensor
RETURN AIR SMOKE DETECTOR SENSOR WITHOUT
ECONOMIZER
The sampling tube is located across the return air opening on the
unit basepan (see Fig. 33). The holes in the sampling tube face
downward, into the return air stream. The sampling tube is con-
nected through tubing to the return air sensor that is 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 that this sensor be relocated to its operating
location and the tubing to the sampling tube be connected. See
"Completing Installation of Return Air Smoke Detector" on
page 20.
Return Air
Smoke Detector
(As Shipped)
Fig. 33 — Typical Return Air Smoke Detector
19
Location
Location