Carrier 50TCQD Installation Instructions Manual page 36

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. 59. 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).
Fig. 59 - - Typical Supply Air Smoke Detector Sensor
Location
Return Air without Economizer — The return air
sampling tube is located across the vertical return air
opening across the face of the coil. See Fig. 60. Install the
return air sampling tube so that the holes in the tube face
downward, into the return air stream for vertical airflow
configuration and horizontally facing away from filters for
horizontal airflow. The sampling tube snaps into the
sensor which protrudes through the back of the control
box.
Return Air with Economizer — The sampling tube is
inserted into the sensor which protrudes through the back
of the control box, placing it across the return air opening
on the unit basepan. See Fig. 60. The holes in the
sampling tube face downward, into the return air stream
for vertical air flow and horizontally facing away from the
dampers for horizontal air flow.
Completing Installation of Return Air Smoke
Sensor:
Return Air Sampling Tube
(Shipping Location)
C09102
Additional Application Data — Refer to Catalog No.
HKRNKA- - 1XA for discussions on additional control
features of these smoke detectors including multiple unit
coordination.
36
1. Locate the magnet; it is shipped in the control box
area.
2. To complete the installation, make sure that the exhaust
is down stream of the sampling tube as shown in Figs.
60 and 61.
Fig. 60 - - Return Air Sampling Tube Location
in Unit without Economizer
Fig. 61 - - Return Air Sampling Tube Location
in Unit with Economizer
Return Air Detector
Sampling Tube
C09135
Return Air Detector
Sampling Tube
C09136