System Sensor DH500ACDC User Manual
INSTALLATION AND MAINTENANCE INSTRUCTIONS
Power 120 VAC (102 - 132) 240 VAC (204 - 264) 24 VAC (20.6 - 26.4)
24 VDC (20 - 30)
Requirements mA rms MAX. mA rms MAX. mA rms MAX.
mA DC MAX.
Device
Standby Alarm Standby Alarm Standby
Alarm Standby Alarm
DH500ACDC
44 52 25
30
65
182 26 87
PA400*
-- 3 --
1.5
--
29 -- 15
RA400ZA*
-- 1.5 --
1 -- 17.3 -- 10
RTS451/RTS451KEY*
-- 1.5 --
1 -- 17.3 -- 10
RTS451**/RTS451KEY
11.5 13 5.5
6.5 140 157 95 103
DH500ACDC Intelligent Air Duct
3825 Ohio Avenue, St. Charles, Illinois 60174
Smoke Detector Housing
Specifications
Length: 14.5 inches (36.7 cm.)
Width: 5 inches (12.7 cm.)
Depth: 4 inches (10.2 cm.)
Weight: 4 lbs. (1.8 kg.)
Operating Temperature Range: 32° to 120°F (0° to 49°C)
Operating Humidity Range: 10% to 93% Relative Humidity
Duct Air Velocity: 500 – 4000 ft./min. (91.4 – 1219.2 m/min.
Power Supply Electrical Ratings For DH500ACDC
The currents shown for the DH500ACDC are maximum values with no accessories.
* All accessory currents are additional to DH500ACDC. There are no additional currents for accessories in standby.
** RTS451/RTS451KEY when the magnet is held in place to initiate an alarm.
24V output maximum load is 80 mA; auxiliary alarm output maximum load is 20 mA.
1-800-SENSOR2, FAX: 630-377-6495
www.systemsensor.com
Auxiliary Relay Contacts
Minimum contact current must be greater than 500 mA at 24 VDC
10 amps maximum at 30 VDC
10 amps maximum at 250 VAC
Before Installing
Please thoroughly read the System Sensor Manual I56473-XX, 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 at no
charge from System Sensor. 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.
D500-07-00 1 I56-432-11R
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.
The DH500ACDC Air Duct Detector Housings are used with
System Sensor’s Model 1551 ionization detector heads and
Model 2551 photoelectronic detector heads (purchased separately). These two smoke detection methods are combined
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 and blowers, change over air handling systems, etc.
This can prevent the distribution of toxic smoke and fire
gases throughout the areas served by the duct system.
Figure 1:
SAMPLING TUBE
FILTERS
CONDUIT HOLES
DUCT DETECTOR
HOUSING
PC BOARD
INSULATOR
DUCT DETECTOR
COVER
SAMPLING TUBE
MOUNTING
SCREWS
DETECTOR HEAD
(SUPPLIED SEPARATELY)
EXHAUST
FILTER ADAPTER
DETECTOR BASE
INLET SAMPLING TUBE
(SUPPLIED SEPARATELY)
O-RINGS
FOAM
GASKETS
HOUSING
MOUNTING SCREWS
TEST MAGNET
TUBE
END
PLUG
See Note 1 below for inlet
sampling tube and detector
supply information.
H0309-00
The DH500ACDCs are built to operate on 120/240 VAC or
24 VAC/DC. Two form-C (SPDT) relay contacts are available for control purposes. Two LEDs on each detector latch
on to provide a local alarm indication. Remote alarm indication is made possible by using the auxiliary alarm output
(see Figure 5). The duct detector can be tested and alarm
can be reset by using the correct respective code commands
from the panel. See panel instructions for details.
Installation Sequence Page
Step 1. Verify duct air flow direction and velocity ............2
Step 2. Drill the mounting holes .....................................2
Step 3. Mount duct housing ...........................................3
Step 4. Install the inlet tube ...........................................3
Step 5. Complete the field wiring....................................5
Step 6. Install the filters .................................................7
Step 7. Perform detector check .......................................7
Step 8. Install the cover .................................................9
Contents Of The Duct Detector Housing Kit
Step 9. Perform the final system check (Testing) .............9
The DH500ACDC Air Duct Detector Housings consist of the
following items: (See Figure 1.)
Step 1. Verify Duct Air Flow Direction And Velocity
The DH500ACDCA is designed to be used in air handling
systems having air velocities up to 500 feet per minute.
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-inch O-rings.
7. Two foam gaskets.
8. Four #6 self-tapping mounting screws for the sampling
tube.
9. One filter adapter.
10. One inlet tube end plug.
11. Two #10 speed nuts.
NOTE: The inlet sampling tube must be ordered separately.
It must be the correct length for the width of the duct
D500-07-00 2 I56-432-11R
where it will be installed. See Table 1 to determine
the inlet tube required for different duct widths. A
smoke detector head (1551 ionization or 2551 for
photoelectronic) must be ordered separately.
Be sure to check engineering specifications 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.
Step 2. Drill The Mounting Holes
Remove the paper backing from the drilling template. Affix
the template to the air duct at the desired mounting loca-
tion. Make sure the template lies flat and smooth on the air
duct. Center punch hole targets and remove the template.
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 2.)
Location of detectors mounted in or on air ducts should
be at least six duct widths downstream from any duct
openings, deflection plates, sharp bends, or branch con-
nections.
HOLE B
HOLE A
DUCT
WALL
SPEED
NUT
Figure 2. Speed nut mounting location:
SCREW HOLES FOR ATTACHING
DETECTOR HOUSING TO DUCT
FOAM
GASKETS
EXHAUST TUBE
(EXTENSION BUSHING)
DUCT DETECTOR
HOUSING
O-RINGS
MOUNTING
SCREWS
SAMPLING
TUBE BUSHING
INLE
T
TUBE
END
PLUG
AIR HOLES
ARROWS
MUST FACE
INTO AIR FLOW
AIR FLOW DIRECTION
FLANGE
Figure 2A. Installation of foam gaskets over sampling tube bushings:
H0116-00
CAUTION: Do not overtighten the screws.
Exception: Where it is physically impossible to locate the
detector accordingly, the detector can be positioned closer
than six duct widths, but as far as possible from the opening, bend, or deflection plates.
Step 3. Mount Duct Housing
Remove the duct housing cover. Slide the foam gaskets over
the tube bushings as shown in Figure 2A. Make sure the
two small holes in the gaskets line up with the two duct
housing 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 secure the duct housing to the duct.
Table 1. Sampling (Inlet) Tubes
TUBE OUTSIDE DUCT WIDTH
ST-1.5 1 to 2 ft. (0.3 to 0.6 m)
ST-3 2 to 4 ft. (0.6 to 1.2 m)
ST-5 4 to 8 ft. (1.2 to 2.4 m)
ST-10 8 to 12 ft. (2.4 to 3.7 m)
H0117-00
Step 4. Install The Inlet Tube
The inlet tube (shown in Figure 3) 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 the width of the duct where it will be installed. The
exhaust tube is molded into the base of the duct housing.
The inlet tube should be installed in the inlet sampling
tube bushing located in the center of the duct detector
housing. (See Figure 2A.) The air inlet holes must face into
the air flow. To assure proper installation, the tube mounting flange is marked with arrows. Mount the inlet tube so
that the arrows point into the air flow. Figure 4 shows the
various combinations of duct detector and tube mounting
configurations with respect to air flow.
Figure 3. Air duct detector inlet sampling tube:
D500-07-00 3 I56-432-11R
H0108-00
WARNING
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
Figure 4. Tube mounting configurations with varying air flow direction and orientation of detector housing.
Vertical as well as horizontal mounting is acceptable.
A. Installation for Ducts Less Than 8 Feet Wide
1. If the inlet tube is longer than the width of the air duct,
Install the inlet tube as follows:
drill a 3/4-inch hole in the duct directly opposite the
hole already cut for the inlet tube.
If the inlet tube is shorter than the width of the air duct,
install the end cap into the inlet tube as shown in Figure
3.
2. Slide the inlet tube into the bushing located in the center
of the duct housing. Position the tube so that the arrows
point into the air flow.
3. Secure the tube flange to the housing bushing with the
two #6 self-tapping screws.
4. For tubes longer than the width of the air duct, the tube
should extend through the opposite side of the duct. If
there are more than 2 holes in the section of the tube
extending from the duct, select a different tube length
using Table 1. Otherwise, trim the end of the tube protruding through the duct so that 1 to 2 inches of the tube
extends outside the duct. Plug this end with the tube
end plug and tape closed any holes in the protruding
section of the tube. Be sure to seal the duct when the
tube protrudes.
5. Any inlet tube over 3 feet long must be supported on the
opposite side of the duct detector housing.
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.
B. 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 accom-
D500-07-00 4 I56-432-11R
plished by using the ST-10 inlet sampling tube.
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 into the bushing located in the center
of the duct housing. Position the tube so that the arrows
point into the air flow. Secure the tube flange to the
housing bushing with the 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 facing the
direction of air flow.
4. Trim the end of the tube protruding through the duct so
that 1 to 2 inches of the tube extends outside the duct.
Plug this end with the tube end plug and tape closed any
holes in the protruding section of the tube. Be sure to
seal the duct when the tube protrudes.
5. Any tube (over 3 feet long) that doesn’t protrude through
the duct (on the side opposite the housing) must be supported by other means.
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 electrician’s tape to close off
some of the sampling holes so that there are a total
of 12 holes spaced as evenly as possible across the
width of the duct.
NOTE: Air currents inside the duct may cause excessive
vibration. This vibration can slowly open the
seal around the tube and permit air to escape. To
prevent this from occurring, a 3-inch floor flange,
H0109-00
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