Smoke Detector Locations - Carrier WeatherMaster 50HCQ04-12 Service And Maintenance Instructions

the sensor housing using four captive screws and forms an air-
tight chamber around the sensing electronics. Each sensor in-
cludes a harness with an RJ45 terminal for connecting to the
controller. Each sensor has four LEDs (for Power, Trouble,
Alarm and Dirty) and a manual test/reset button (on the left-
side of the housing).
DUCT SMOKE SENSOR
CONTROLLER
CONTROLLER HOUSING
AND ELECTRONICS
CONDUIT COUPLINGS
(SUPPLIED BY INSTALLER)
FASTENER (2X)
ALARM
Fig. 47 — Controller Assembly
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.
For installations using two sensors, the duct smoke detector
does not differentiate which sensor signals an alarm or trouble
condition.
CONDUIT NUTS
(SUPPLIED BY INSTALLER)
CONDUIT SUPPORT PLATE
TERMINAL BLOCK COVER
COVER GASKET
(ORDERING OPTION)
CONTROLLER
COVER
TROUBLE
POWER
TEST/RESET
SWITCH
A
SEE DETAIL
INTAKE
GASKET
TSD-CO2
(ORDERING OPTION)
PLUG
SAMPLING TUBE
(ORDERED SEPARATELY)
DETAIL A
MAGNETIC
TEST/RESET
SWITCH
Fig. 48 — 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. 49. 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.
SUPPLY AIR
SMOKE DETECTOR
Fig. 49 — 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. 50. 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 "Completing Installation of Return Air Smoke
Sensor" for installation steps.)
27
EXHAUST TUBE
DUCT SMOKE SENSOR
EXHAUST GASKET
SENSOR HOUSING
AND ELECTRONICS
COVER GASKET
(ORDERING OPTION)
COUPLING
ALARM POWER
TROUBLE DIRTY
Location
SENSOR
COVER