Carrier WeatherMaker 50KCQ A04 Series, Service And Maintenance Instructions

Page: 27 / 80

27
Fig. 40 — Smoke Detector Sensor
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 cham-
ber. When a sufficient amount of smoke is detected in the sens-
ing chamber, the sensor signals an alarm state and the control-
ler 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.
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. 41. 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. 41 — Typical Supply-Air Smoke Detector
Sensor Location
RETURN AIR WITHOUT ECONOMIZER
The sampling tube is located across the return air opening on
the unit base pan. See Fig. 42. The holes in the sampling tube
face downward, into the return air stream. The sampling tube is
connected by tubing to the return air sensor that is mounted on
a bracket high on the partition between return filter and con-
troller location. (This sensor is shipped in a flat-mounting loca-
tion. Installation requires that this sensor be relocated to its op-
erating location and the tubing to the sampling tube be con-
nected. See “Completing Installation of Return Air Smoke
Sensor” on page 28 for installation steps.)
Fig. 42 — Typical Return-Air Detector Location
RETURN AIR 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 base pan. See Fig. 43. The holes in the sampling tube
face downward, into the return air stream. The sampling tube is
connected via tubing to the return air sensor that is mounted on
a bracket high on the partition between return filter and con-
troller location. (This sensor is shipped in a flat-mounting loca-
tion. Installation requires that this sensor be relocated to its op-
erating location and the tubing to the sampling tube be con-
nected. See “Completing Installation of Return Air Smoke
Sensor” on page 28 for installation steps.)
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)
SMOKE DETECTOR
SENSOR
*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