System Sensor DH400ACDCP User Manual
INSTALLATION AND MAINTENANCE INSTRUCTIONS
DH400ACDCP Air Duct Smoke Detector
Before Installing
Please thoroughly read the System Sensor Guide for
Proper Use of Smoke Detectors in Duct Applications
(A05-1004), which provides detailed information on detector spacing, placement, zoning, wiring, and special
applications. Copies of this manual are available online
at www.systemsensor.com or via System Sensor’s toll free
fax-back service, Documents on Demand at 800/736-7672.
NFPA Standards 72 and 90A should also be referenced for
detailed information.
NOTICE: This manual should 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.
Table of Contents Page
[1] General Description 1
[2] Exploded View of Duct Detector Components 2
[3] Contents of the Duct Detector Kit 2
[4] Limitations of Duct Detectors 2
[5] Installation Sequence 2
[6] Duct Detector Maintenance and Test Procedures 8
[7] Detector Cleaning Procedures 10
[8] Specifications 12
Warranty 13
Detector Test log 16
List of Tables and Figures Page
Fig. 1: Duct Detector Exploded View 2
Fig. 2: Installation of Sampling Tube Gaskets 3
Fig. 3: Mounting Location of Speed Nuts 3
Table 1: Inlet Sampling Tube Selection 3
Fig. 4: Inlet Sampling Tube 4
Fig. 5: Sampling Tube Mounting Configurations 4
Fig. 6: Wiring Diagram 6
Fig. 7: Wiring Diagram – No Control Panel 7
Fig. 8: Wiring Diagram – Accessories 8
Fig. 9: Sampling Tube Filter Installation 8
Fig. 10: Testing Detector Alarm 9
Fig. 11: Detector Head Removal 9
Fig. 12: RTS451/RTS451KEY Test Coil Installation 10
Fig. 13: Photo Head Exploded View 11
[1] 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.
Model DH400ACDCP Air Duct Smoke Detector utilizes
photoelectric technology for the detection of smoke. This
smoke detection method, when combined with an efficient
housing design, samples air passing through the 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 and blowers, change over air handling systems, etc. These actions
can facilitate the management of toxic smoke and fire gases
throughout the areas served by the duct system.
DH400ACDCP detectors are designed to operate from 24
VDC, 24 VAC, 120 VAC, or 240 VAC. Alarm and supervisory
relay contacts are available for control panel interface
(alarm initiation), HVAC control, and other auxiliary functions. These detectors are not designed for 2-wire application.
For testing, the alarm can be enabled by a magnet activated
test switch, by insertion of a calibrated test card into the
sensing chamber (photoelectronic version only), or by the
optional remote test station. The duct smoke detectors latch
into alarm state when alarm occurs. LEDs on each detector
illuminate to provide local alarm indication, and optional
accessories offer a variety of annunciation capabilities.
The detector can be reset by a momentary power interruption, by the magnet activated reset switch, or by the
optional remote test station.
3825 Ohio Avenue, St. Charles, Illinois 60174
1-800-SENSOR2, FAX: 630-377-6495
www.systemsenor.com
D400-13-00 1 I56-555-09R
WARNING
WARNING
WARNING
CAUTION
[2] Figure 1. Exploded view of duct detector components:
SAMPLING TUBE
FILTERS
CONDUIT HOLES
DUCT DETECTOR
HOUSING
TERMINAL STRIP
PC BOARD
INSULATOR
DUCT DETECTOR
COVER
SAMPLING TUBE
MOUNTING
SCREWS
DETECTOR HEAD
EXHAUST
FILTER ADAPTER
DETECTOR BASE
INLET SAMPLING TUBE
(SUPPLIED SEPARATELY)
O-RINGS
FOAM
GASKETS
HOUSING
MOUNTING SCREWS
TEST MAGNET
TUBE
END
PLUG
[3] Contents Of The Duct Detector Kit
1. Complete housing base and cover assembly
2. Two #10 sheet metal mounting screws
3. Two sampling tube filters
4. One test magnet
5. Drilling template
6. Two 5/16 O-rings
7. Two rubber tube bushing seals
8. Four #6 self-tapping mounting screws for the sampling
and optional exhaust tube extension
9. One filter adapter
10.One inlet tube end plug
11.Two #10 speed nuts
NOTE: The inlet sampling tube must be ordered sepa-
rately. It must be the correct length for the width
of the duct where it will be installed. See Table 1
on page 4 to determine the inlet tube required for
different duct widths.
[4] Limitations Of Duct Detectors
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 system.
System Sensor supports this position and strongly recommends that the user read NFPA Standards 90A, 72, and 101.
The DH400ACDCP Air Duct Smoke Detectors are listed per
UL 268A.
H0249-00
This device will not operate without electrical power.
Frequently, fire situations may cause an interruption of
power. The system safeguards should be discussed with
your local fire protection specialist.
This device does not sense smoke unless the ventilation
system is operating.
For this detector to function properly, it MUST be installed
according to the instructions in this manual. Furthermore,
the detector MUST be protected from the elements and
operated within ALL electrical and environmental specifications listed in this manual. Failure to comply with these
requirements may prevent the detector from activating
when smoke is present in the air duct.
[5] Installation Sequence
Step Page
[5.1] Verify duct air flow direction and velocity 2
[5.2] Drill the mounting holes 3
[5.3] Secure the detector housing to the duct 3
[5.4] Install the sampling tube 3
[5.5] Complete the field wiring 5
[5.6] Install the filters and check pressure differential 8
[5.7] Perform detector check 8
[5.8] Install the cover 8
[5.1] Verify Duct Air Flow Direction And Velocity
Model DH400ACDCP detectors are designed to be used in
air handling systems having air velocities of 500 to 4000
D400-13-00 2 I56-555-09R
feet per minute. Be sure to check engineering specifications
SCREW HOLES FOR ATTACHING
DETECTOR HOUSING TO DUCT
FOAM GASKETS
EXHAUST TUBE
(EXTENSION BUSHING)
DUCT DETECTOR
HOUSING
O-RINGS
MOUNTING
SCREWS
INLET SAMPLING
TUBE BUSHING
HOLE B
HOLE A
DUCT
WALL
SPEED
NUT
to ensure that the air velocity in the duct falls within these
parameters. If necessary, use a velocity meter to check the
air velocity in the duct.
[5.2] Drill The Mounting Holes
Remove the paper backing from the mounting template
supplied. Affix the template to the duct at the desired
mounting location. Make sure the template lies flat and
smooth on the duct. Center punch holes A and B. Drill the
holes as indicated on the template. Slide the two speed nuts
over the two small holes (hole A) next to the sampling tube
bushing holes (hole B) previously drilled in the duct. (See
Figure 3.)
[5.3] Secure The Detector Housing To The Duct
Remove the duct housing cover. Slide the foam gaskets over
the tube bushings as shown in Figure 2. Make sure the two
small holes in the gaskets line up with the two base mounting holes. Put one 5/16-inch O-ring over each of the two
#10 sheet metal screws. Use the two sheet metal screws to
screw the detector housing to the duct. CAUTION: Do not
overtighten the screws.
Figure 2. Installation of foam gaskets over sampling
tube bushings:
[5.4] Install The Inlet
The inlet tube (shown in Figure 4) is identified by a series
of air inlet holes on the tube. This tube must be purchased
separately. Order the correct length, as specified in Table 1,
for width of the duct where it will be installed. The exhaust
tube is molded into the base of the duct housing, and the
A2440-00 Exhaust Tube Extension is available as an accessory in those cases where the molded exhaust port does
not extend at least 2 inches into the duct.
The inlet tube is always installed in the centermost housing bushing, with air inlet holes facing into the air flow.
To assist proper installation, the tube’s mounting flange is
marked with arrows. Make sure the inlet tube is mounted
so that the arrows point into the air flow. Figure 5 shows
the various combinations of tube mounting configurations
with respect to air flow.
Mounting the detector housing in a vertical orientation is
acceptable, provided that the air flows directly into the
sampling tube holes as indicated in Figure 4.
Table 1. Inlet tubes required for different duct
widths:
Outside Duct Width Inlet Tube Required
1 to 2 ft. ST-1.5
2 to 4 ft. ST-3
4 to 8 ft. ST-5
8 to 12 ft. ST-10
H0238-00
Figure 3. Speed nut mounting location:
D400-13-00 3 I56-555-09R
H0116-00
Figure 4. Air duct detector inlet sampling tube:
INLET
TUBE
END
PLUG
AIR HOLES
ARROWS
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
AIR FLOW
DIRECTION
DETECTOR
HOUSING
DOTS INDICATE POSITION OF
SAMPLING TUBE HOLES
AIR FLOW
DIRECTION
DETECTOR
HOUSING
INLET
TUBE
EXHAUST
TUBE
AIR FLOW
DIRECTION
EXHAUST
TUBE
INLET
TUBE
INLET
TUBE
EXHAUST
TUBE
DETECTOR
HOUSING
AIR FLOW
DIRECTION
EXHAUST
TUBE
INLET
TUBE
DETECTOR
HOUSING
A.
B.
C.
D.
HORIZONTAL MOUNTING OF HOUSING
VERTICAL MOUNTING OF HOUSING
WARNING
Figure 5. Tube mounting configurations with varying air flow direction:
H0108-00
H0109-00
[5.4.1] Installation For Ducts Less Than 8 Feet Wide
1. If the tube is longer than the width of the air duct, drill
a 3/4-inch hole in the duct directly opposite the hole
already cut for the inlet tube. If the tube is shorter than
the width of the air duct, install the end plug into the
inlet tube as shown in Figure 4. Sampling tubes over 3
ft. long must be supported at the end opposite the duct
detector.
outside the duct. Plug this end with the end plug and
tape closed any holes in the protruding section of the
tube. Be sure to seal the duct when the tube protrudes.
In no case should more than 2 air inlet holes be cut off the
tube. There must be a minimum of 10 holes in the tube exposed to the air stream.
2. Slide the tube into the centermost housing bushing. Position the tube so that the arrows point into the air flow.
3. Secure the tube flange to the housing bushing with two
#6 self-tapping screws.
4. For tubes longer than the width of the air duct, the tube
should extend out of the opposite side of the duct. If
there are more than 2 holes in the section of the tube
extending out of the duct, select a different length using
Table 1. Otherwise, trim the end of the tube protruding
through the duct so that 1 to 2 inches of the tube extend
D400-13-00 4 I56-555-09R
[5.4.2] Installation For Ducts More Than 8 Feet Wide
NOTE: To install inlet tubes in ducts more than 8 feet
wide, work must be performed inside the air
duct. Sampling of air in ducts wider than 8 feet
is accomplished by using the ST-10 inlet sampling
tube. If the tube is shorter than the width of the
air duct, install the end plug into the inlet tube as
shown in Figure 4 and support the end opposite
the duct detector.
Install the inlet tube as follows:
1. Drill a 3/4-inch hole in the duct directly opposite the
hole already drilled for the inlet tube.
2. Slide the inlet tube with the flange into the centermost
housing bushing. Position the tube so that the arrows
point into the air flow. Secure the tube flange to the
housing bushing with two #6 self-tapping screws.
3. From inside the duct, couple the other section of the
inlet tube to the section already installed using the 1/2inch conduit fitting supplied. Make sure that the holes
on both of the air inlet tubes are lined up and facing into
the air flow.
4. Trim the end of the tube protruding through the duct so
that 1 to 2 inches of the tube extend outside the duct.
Plug this end with the end plug and tape closed any
holes in the protruding section of the tube. Be sure to
seal the duct when the tube protrudes.
NOTE: An alternate method to using the ST-10 is to use
two ST-5 inlet tubes. Remove the flange from one
of the tubes and install as described above. After
the installation, use electrical tape to close off
some of the sampling holes so that there is a total of 10 to 12 holes spaced as evenly as possible
across the width of the duct.
Air currents inside the duct may cause excessive vibration,
especially when the longer sampling tubes are used. In
these cases a 3 inch floor flange (available at most plumbing supply stores) may be used to fasten the sampling tube
to the other side of the duct. When using the flange/connector mounting technique, drill a 1 inch to 1-1/4-inch hole
where the flange will be used.
[5.4.3] Modifications Of Inlet Sampling Tubes
There may be applications where duct widths are not what
is specified for the installation. In such cases, it is permissible to modify an inlet sampling tube that is longer than
necessary to span the duct width.
[5.5] Field Wiring
Installation Guidelines
All wiring must be installed in compliance with the National
Electrical Code and the local codes having jurisdiction.
Proper wire gauges should be used. The conductors used
to connect smoke detectors to control panels and accessory
devices should be color-coded to reduce the likelihood of
wiring errors. Improper connections can prevent a system
from responding properly in the event of a fire.
For signal wiring, (the wiring between interconnected detectors or from detectors to auxiliary devices), it is usually
recommended that single-conductor wire be no smaller
than 18 gauge. The duct detector terminals accommodate
wire sizes up to 14 gauge. The last foot of conduit should
be flexible steel conduit (available in electrical supply
houses), which facilitates installation and puts less strain
on the conduit holes in the housing. Solid conduit connections may be used, if desired.
Smoke detectors and alarm system control panels have
specifications for allowable loop resistance. Consult the
control panel manufacturer’s specifications for the total
loop resistance allowed for the particular model control
panel being used before wiring the detector loop.
Wiring Instructions
The DH400ACDCP detectors are designed for easy wiring.
The housing provides a terminal strip with clamping plates.
Wiring connections are made by stripping about 3/8-inch
of insulation from the end of the wire, sliding the bare end
under the plate, and tightening the clamping plate screw.
The DH400ACDCP duct detector is designed to operate
from 24 VDC, 24 VAC, 120 VAC, or 240 VAC.
The detector may be wired for interconnection to UL listed
control panels, or for stand alone service per NFPA 90A.
Refer to the wiring diagrams of Figures 6, 7, and 8 to select
the appropriate circuit for your application.
Use a 0.193-inch diameter (#11) drill and add the appropriate number of holes so that the total number of holes
exposed to the air flow in the duct is 10 to 12. Space the
additional holes as evenly as possible over the length of the
tube.
D400-13-00 5 I56-555-09R
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