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P/N 3101069-EN • REV 005 • ISS 19OCT20 

Selecting an appropriate sampling tube: 

•  Select a sampling tube that extends at least two-thirds across 

the width of the duct. Refer to Table 3 below. 

•  For duct widths greater than 36 inches, use a sampling tube that 

is longer than the width of the duct. 

•  Sampling tubes are available in the following lengths: 

Table 3: Sampling tubes 
Model 

Length (in.) 

Model 

Length (in.) 

SD-T8  

SD-T42 

42 

SD-T18  

18 

SD-T60 

60 

SD-T24 

24 

SD-T78 

78 

SD-T36  

36 

SD-T120 

120 

 

To assemble the detector: 

1.  Assemble the duct smoke detector as shown in Figure 1. 
2.  Rotate the air sampling tube so the inlet holes face the direction 

of airflow. 

3.  The sampling tube is normally installed from the rear, but it can 

also be installed from the front of the detector as shown in 

Figure 2. This method requires that you remove the detector 

cover. 

Figure 1: Duct detector assembly 

 

(1)  Exhaust tube socket 

(2)  Sampling tube socket 

(3)  Detector 

(4)  Coupling 

(5)  Sampling tube 

 

(6)  Plug 

(7)  Thick gasket 

(8)  Thin gasket 

(9)  Exhaust tube 

Figure 2: Sampling tube installation 

 

(1)  Sampling tube socket 

(2)  Detector 

(3)  Sampling tube (fully assembled) 

To install the detector: 

1.  Attach the drill template to the HVAC duct at the desired 

mounting location. 

2.  Drill (or punch) the mounting holes where indicated. 
3.  Remove any rough edges from the holes. 
4.  When using an air sampling tube that is longer than the width of 

the duct: 

• 

Drill a 3/4 in. hole on the opposite side of the duct for the 

tube to pass through. 

• 

Cut the tube so that approximately one inch of the tube 

extends through the duct. Seal the opening around the 

tube with an approved duct sealant as shown in Figure 3. 

Note

: Support sampling tubes longer than 36 inches at both 

ends of the duct. See Figure 3. 

5.  Mount the duct smoke detector on the HVAC duct and secure it 

using the two sheet metal screws provided. See Figure 4. 

7.  Verify that all field wiring is free of opens, shorts, and ground 

faults. 

8.  Make all wiring connections as shown in Figure 6. 
9.  Set the module address as follows: 

•  Use a screwdriver to adjust the two rotary switches on the 

front of the module. See Figure 5. 

•  Set the TENS rotary switch (0 through 12) for the 10s and 

100s digit. 

•  Set the ONES rotary switch for the 0 through 9 digit. 
For example: for device address 21, set the TENS rotary switch 

to 2, and then set the ONES rotary switch to 1. 
For a list of detector addresses, see Table 4 on page 3. 

10.  Set jumper JP3 to the appropriate position. See Table 1 and 

Figure 6. 

11.  Verify that the air pressure differential value falls within the 

specified operating range of the detector in accordance with 

procedures specified in “Verifying the air pressure differential” 

on page 4. 

12.  After completing the installation of the duct smoke detector, test 

the detector in accordance with procedures specified in “Testing 

the duct smoke detector” on page 5 to ensure it is operating 

correctly. 

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