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Before installing detectors, please thoroughly read the NEMA 

Guide for Proper Use of Smoke Detectors in Duct Applications,

 which provides detailed 

information on detector spacing, placement, zoning, wiring, and special applications. Copies of this manual are available from NEMA (National Electrical 
Manufacturers Association, 2101 L Street NW, Washington, DC 20037). NFPA Standards 72 and 90A should also be referenced for detailed informa-
tion.

 

NOTICE:

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

IMPORTANT: 

This detector must be tested and maintained regularly following NFPA 72 requirements. The detector should be cleaned at least once 

a year.

GENERAL DESCRIPTION

An HVAC system supplies conditioned air to virtually every area of a building. Smoke introduced into this air duct system is 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. 

The DH300PL air duct smoke detector is a photoelectric detector. This smoke detection method combines with an efficient housing design that samples 
air passing through a duct and allows detection of a developing hazardous condition. When sufficient smoke is sensed, an alarm signal is initiated at 
the fire control panel monitoring the detector, and appropriate action can be taken to shut off fans, blowers and change over air handling systems, etc. 
This can prevent the distribution or it can isolate toxic smoke and fire gases throughout the areas served by the duct system.

Two LEDs on each detector may illuminate, if programmed by the system control panel, to provide a local alarm indication. There is also a remote 
alarm output for use with auxiliary devices. The DH300PL has remote test capability with the RTS451/RTS451KEY Remote Test Station.

CONTENTS OF THE DUCT SMOKE DETECTOR HOUSING KIT

The DH300PL Duct Smoke Detector consists of the following items: (See Figure 1.)

DH300PL INTELLIGENT PHOTOELECTRONIC DUCT SMOKE DETECTOR

WITH EXTENDED AIR SPEED RANGE

INSTALLATION AND MAINTENANCE INSTRUCTIONS

Figure 1: Exploded View Of Duct Smoke Detector Components

NOTE: 

For ducts over 1

1

⁄ 2

 feet, longer sampling tubes must be ordered to complete the installation. They must be the correct length for the width of 

the duct where they will be installed. See Table 1 on page 3 to determine the sampling tube required for different duct widths.

WARNING

LIMITATIONS OF DUCT DETECTORS 

WARNING

The National Fire Protection Association has established that DUCT DETECTORS 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 sys-
tem.

1.  Complete duct smoke detector  assembly with 

sensor

2.  Two #10 x 1

1/4

 sheet metal mounting screws

3.  Two sampling tube filters
4.  One test magnet
5.  Drilling template
6.  Two foam gaskets
7.  Four #6-self tapping mounting screws for 

the sampling tube and optional exhaust tube 
extension

8.  One sampling tube end cap
9.  One plastic sampling tube
10.  One #8 self-tapping screw for plastic sampling 

tube   

NOTE: A detector sensor board DOES NOT 
need to be ordered separately.

Contents Of The  

Duct Smoke Detector

J500-42-00 

I56-2198-003R

 

Johnson Controls Inc., 507 E. Michigan St., Milwaukee, WI 53201 

FOAM

GASKETS

PLASTIC

SAMPLING TUBE

SAMPLING TUBE

FILTERS

PLASTIC SAMPLING TUBE

SELF-TAPPING SCREW

DETECTOR

COVER

DETECTOR BOARD

CONDUIT HOLES

DETECTOR

HOUSING

TERMINAL STRIP

POWER BOARD

COVER MOUNTING

SCREWS

H0100-00

Summary of Contents for DH300PL

Page 1: ...also a remote alarm output for use with auxiliary devices The DH300PL has remote test capability with the RTS451 RTS451KEY Remote Test Station CONTENTS OF THE DUCT SMOKE DETECTOR HOUSING KIT The DH300PL Duct Smoke Detector consists of the following items See Figure 1 DH300PL INTELLIGENT PHOTOELECTRONIC DUCT SMOKE DETECTOR WITH EXTENDED AIR SPEED RANGE INSTALLATION AND MAINTENANCE INSTRUCTIONS Figu...

Page 2: ...emplate supplied Affix the template to the duct at the desired mounting location Make sure the tem plate lies flat and smooth on the duct Center punch holes A and B Drill the holes as indicated on the template 2 1 Sampling Tube Installation for Ducts Less Than 11 2 Feet Wide see Figure 2 1 Remove the front cover 2 Slide the plastic sampling tube into the housing bushing and extend it the full widt...

Page 3: ...12 ft 2 4 to 3 7 m ST 10 Must extend a minimum of 2 3 the duct width J500 42 00 3 I56 2198 003R SCREW HOLES FOR ATTACHING HOUSING TO DUCT WORK Figure 3 Installation of foam gaskets over sampling tube bushings Figure 5 Tube mounting configurations with varying air flow direction SAMPLING TUBE END CAP AIR HOLES ARROW MUST FACE INTO AIR FLOW AIR FLOW DIRECTION FLANGE Figure 4 Air duct detector sampli...

Page 4: ...ate wire sizes up to 12 gauge The last foot of conduit should be flexible conduit available in electrical supply houses which facilitates easier installation and puts less strain on the conduit holes in the housing Solid conduit con nections may be used if desired Smoke detectors and alarm system control panels have specifications for Signaling Line Circuit SLC wiring Consult the control panel man...

Page 5: ...sing Aerosol Smoke This test is intended for low flow systems 100 500 FPM If the air speed is greater than 500 FPM use a conventional manometer to measure differ ential pressure between the sampling tubes as described in 9 1 1 Drill a 1 4 hole 3 feet upstream from the duct smoke detector With the air handler on measure the air velocity with an anemometer Air speed must be at least 100 FPM Spray ae...

Page 6: ...nce exceeds 10 replace the filters In no case should the pressure differential fall below 0 0015 inches of water 9 2 Standby Alarm And Sensitivity Tests 9 2 1 Standby And Trouble Standby If programmed by the system control panel look for the presence of the flashing LEDs through the transparent housing cover The LED will flash with each communication Trouble If programmed by the system control pan...

Page 7: ...tion facilitates test of the alarm capability of the duct smoke detector These accessories provide the stimulus to initiate an alarm condition at the detector The detector is self restoring when the accessory test stimulus is removed Verify that the system control panel has reset 9 2 3 Sensitivity Tests Notify the proper authorities that the smoke detector system is undergoing maintenance and that...

Page 8: ... Any smoke detector fire alarm equipment or any component of that system which fails shall be repaired or replaced as soon as possible Please refer to insert for the Limitations of Fire Alarm Systems 10 Board Replacement 10 1 Sensor Board Replacement 1 Remove the two sensor board mounting screws 2 Pull gently on the board to remove it 3 To replace the board align the board mounting features holes ...

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