Bryant 548J*14D Smoke Detector Locations, Supply Air, Return Air without Economizer

Models: 548J*14D

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Smoke Detector Locations

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

 

548J*14D

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. 51. Access

 

is through the left side blower 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). The controller is located on a

 

bracket to the right of the return filter, accessed through

 

the lift-off filter panel.

Smoke Detector Sensor

C08245

Fig. 51 - Typical Supply Air Smoke Detector Sensor

Location

Return Air without Economizer —

The sampling tube is located across the return air opening on the unit basepan. See Fig. 52. 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 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 connected. See “Completing Installation of Return Air Smoke Sensor:” on page 29 for details.)

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 basepan. See Fig. 52. 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 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 connected. See the following installation procedure.)

Flexible

Exhaust Tube

Return Air

Sampling Tube

C10330

Fig. 52 - Return Air Sampling Tube Location

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Bryant 548J*14D installation instructions Smoke Detector Locations, Typical Supply Air Smoke Detector Sensor Location