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SS-400-006 

1 I56-3535-002R

Table of Contents 

Page

[1] Limitations of Duct Smoke Detectors   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  1
[2] General Description    .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  1
[3] Contents of the Duct Smoke Detector Kit   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2
[4] Detector Installation   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2
[5] Sampling Tube Installation    .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3
[6] Measurement Tests   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3
[7] Field Wiring   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4
[8] Verification of Operation   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4
[9] Dectector Cleaning Procedures    .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5
[10] Sensor Replacement    .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5
Warranty   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  6

BEfORE InSTaLLInG 

Please thoroughly read System Sensor’s

 Guide for Proper Use of Smoke Detec-

tors in Duct Applications

 (I56-473-XX), which provides detailed information 

on detector spacing, placement, zoning, wiring, and special applications . Cop-
ies of this manual are available from System Sensor . NFPA Standards 72, 76, 
and 90A should also be referenced for detailed information . 

NOTICE:

 This manual should be left with the owner/user of this equipment .

All sensors must be tested after installation and periodically thereafter . Test-
ing methods must satisfy the Authority Having Jurisdiction (AHJ) . Sensors 
offer maximum performance when tested and maintained in compliance with 
NFPA 72 . 

SPECIfICaTIOnS

Length: 

14 .4 inches

Width: 

5 .0 inches

Depth: 

2 .9 inches

Weight: 

1 .6 pounds

Operating Temperature Range: 

32° to 100°F (0° to 38°C)

Operating Humidity Range: 

10% to 93% Relative Humidity

Duct Air Velocity: 

300 – 4000 ft ./min .

Voltage Range: 

15 – 32 VDC Peak

Standby Current (nominal): 

230uA at 24 VDC (no communication)

 

330uA at 24 VDC (one communication every 5 sec . with LED enabled)

LED current (nominal): 

6 .5mA at 24 VDC

[1]LImITaTIOnS Of DuCT SmOkE DETECTORS 

WARNING

The National Fire Protection Association has established that DUCT DETEC-
TORS MUST NOT BE USED AS A SUBSTITUTE FOR OPEN AREA DETECTOR 
PROTECTION as a means of providing life safety . Nor are they a substitute for 
early warning in a building’s regular fire detection system .

System Sensor supports this position and strongly recommends that the user 
read NFPA Standards 90A, 72, and 101 . The DNRHS Air Duct Smoke Detectors 
are listed per UL 268A .

This device will not operate without electrical power . Fire situations may 
cause an interruption of power . The system safeguards should be discussed 
with your local fire protection specialist .

This device will not sense smoke unless the ventilation system is operating 
and the cover is installed .

For this detector to function properly, it MUST be installed according to the 
instructions in this manual . Furthermore, the detector MUST be operated within 
ALL electrical and environmental specifications listed in this manual and the 
sensor head installation manual . Failure to comply with these requirements 
may prevent the detector from activating when smoke is present in the air duct .

[2] GEnERaL DESCRIPTIOn

An HVAC system supplies conditioned air to virtually every area of a building . 
Smoke introduced into this air duct system will be distributed to the entire 
building . Smoke detectors designed for use in air duct systems are used to 
sense the presence of smoke in the duct . In facilities with large air changes per 
hour, airflow can carry smoke particles directly to the HVAC system . Per NFPA 
76 Very Early Warning Fire Detection (VEWFD) sensors shall be installed to 
monitor return air from the space . The DNRHS can be installed to monitor the 
return air from the space in order to meet NFPA 76 requirements .

I56-3535-00

2R

DnRHS Intelligent
air Duct Smoke Detector

InSTaLLaTIOn anD maInTEnanCE InSTRuCTIOnS

3825 Ohio Avenue, St . Charles, Illinois 60174

1-800-SENSOR2, FAX: 630-377-6495

www .systemsensor .com

H0569-06

EXHAUST TUBE

SENSOR HEAD

SENSOR MODULE COVER

WIRING COMPARTMENT COVER

WIRING COMPARTMENT

SENSOR MODULE

SAMPLING 

TUBE

NOTE: SENSOR HEAD IS ONLY 

INCLUDED ON SPECIFIED MODELS.

SOLD 

SEPERATELY

fIGuRE 1:

Summary of Contents for DNRHS

Page 1: ... a building s regular fire detection system System Sensor supports this position and strongly recommends that the user read NFPA Standards 90A 72 and 101 The DNRHS Air Duct Smoke Detectors are listed per UL 268A This device will not operate without electrical power Fire situations may cause an interruption of power The system safeguards should be discussed with your local fire protection specialis...

Page 2: ...on the duct 4 3 1 For rectangular side by side mounting configuration Center punch at 4 target centers 2 A for sampling tubes and 2 B for the rectangular configuration mounting tabs as shown on mounting template Drill pilot holes at target A centers and cut two 1 375 inch diameter holes using a 13 8 inch hole saw or punch Drill 156 inch diameter holes using a 5 32 inch drill at target B centers 4 ...

Page 3: ...isture drainage away from the detector The sampling tube should be angled at least 1 4 downward for every 12 of duct width There should be 10 to 12 holes spaced as evenly as possible across the width of the duct If there are more than 2 holes in the section of the tube extending out of the duct select a shorter tube using Table 1 Otherwise trim the tube to leave approximately 1 to 2 inches extendi...

Page 4: ...ctors as recommended in NFPA 72 The tests contained in this manual were devised to assist maintenance personnel in verification of proper detector operation Before conducting these tests notify the proper authorities that the smoke detection system will be temporarily out of service Disable the zone or system under test to prevent unwanted alarms 8 4 1 Test THE UNIT 1 M02 04 00 Magnet Test not inc...

Page 5: ...Ds to align the cover and then gently pushing it until it locks into place 8 Reinstall the detector 9 2 Reinstallation 1 Reinstall the detector in its housing 2 Restore system power 3 Perform Detector Check 4 Notify the proper authorities testing has been completed and the smoke detector system is back in operation 10 Sensor Replacement 1 Remove the sensor head by rotating counterclockwise 2 Pull ...

Page 6: ...for a Return Authorization number send defective units postage prepaid to System Sensor Returns Department RA __________ 3825 Ohio Avenue St Charles IL 60174 Please include a note describing the malfunction and suspected cause of failure The Company shall not be obligated to replace units which are found to be defective because of damage unreasonable use modifications or alterations occurring afte...

Page 7: ...SS 400 006 7 I56 3535 002R ...

Page 8: ...ETECTOR TEST LOG Detector Identification Information Manufacturer Detector Model Serial Number Date Installed Description of Detector Location The Results and Maintenance Data Date Tested Test Description Test Results Maintenance Performed Comments ...

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