Bryant 551J Smoke Detector Locations, Typical Supply Air Smoke Detector Sensor Location

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. 31. 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
551J		(into a high pressure area). The controller is located on a
	j	bracket to the right of the return filter, accessed through
		the lift-off filter panel.

Smoke Detector Sensor

C08245

Fig. 31 - 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. 32. 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:” for details.)

Return Air Detector module (shipping position shown)*

Controller module

Return Air Detector Sampling Tube

*RA detector must be moved from shipping position to operating position by installer

C07307

Fig. 32 - 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 basepan. See Fig. 33. 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.)

Return Air

Sampling Tube

C08129

Fig. 33 - Return Air Sampling Tube Location

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