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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 sup-
port the end opposite the duct smoke 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. Make sure the hole is 1
to 2″ below the inlet hole on the opposite side of the
duct to allow for moisture drainage.
2. Slide the inlet tube with the flange into the housing
bushing that meets the air flow first. 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 sections of the in-
let tube to the section already installed using the
1
/2-inch
conduit fittings 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″ 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 are a total
of 10 to 12 holes spaced as evenly as possible
across the width of the duct.
NOTE: 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 permis-
sible to modify an inlet sampling tube that is longer than
necessary to span the duct width.
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.
NOTE: This procedure should only be used as a temporary
fix. It is not intended as a permanent substitute for
ordering the correct length tubes.
[5.5] Install The Filters
To install the sampling tube filters, simply push the filters
into the sampling and exhaust tube holes, as shown in Fig-
ure 6. If a metal sampling tube is used, install the filters
over the tube ends.
Figure 6. Sampling tube filter installation:
A78-2106-01
CAUTION
Filters require periodic cleaning or replacement, depending
on the amount of dust and dirt accumulated. Visually in-
spect the filters at least quarterly; inspect them more often
if the dust accumulation warrants it. See Section [6] for
more information. Replacement filters can be ordered from
System Sensor, 3825 Ohio Ave., St. Charles, IL 60174. (Ex-
haust tube/intake tube filter P/N F36-09-00)
[5.6] Field Wiring
Wiring Installation Guidelines
All wiring must be installed in compliance with the Na-
tional Electrical Code and the local codes having jurisdic-
tion. Proper wire gauges should be used. The conductors
used to connect smoke detectors to control panels and ac-
cessory devices should be color-coded to prevent wiring
mistakes. Improper connections can prevent a system from
responding properly in the event of a fire.
For signal wiring, (the wiring between interconnected de-
tectors or from detectors to auxiliary devices), it is usually
recommended that single conductor wire be no smaller
than 18 gauge. The duct smoke detector terminals accom-
modate 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
connections may be used if desired.
D100-68-00 4 I56-1147-07
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 DH100ACDC 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 clamp-
ing plate screw.
[5.7] Perform Detector Check
1. Perform STANDBY AND TROUBLE TEST per Section
[6.2.1].
2. Perform MAGNET TEST per Section [6.2.2.1]. The
RTS451 test of Section [6.2.2.2] may substitute for this
requirement.
3. Perform AIR FLOW TEST per Section [6.1.1].
4. Perform SMOKE RESPONSE TEST per Section [6.1.2].
5. Perform SENSITIVITY TEST per Section [6.2.3].
[5.8] Install The Cover
Install the cover using the four screws that are captured in
the housing cover. Be certain filters are installed as speci-
fied in Section [5.5]. Make sure that the cover fits into the
base groove and that all gaskets are in their proper posi-
tions. Tighten the four screws.
[6] Duct Smoke Detector Maintenance And Test
Procedures
Test and maintain duct detectors as recommended in NFPA
72. The tests contained in this manual were devised to as-
sist maintenance personnel in verification of proper detec-
tor 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.
[6.1] Smoke Entry Tests
[6.1.1] Air Flow
To verify sufficient sampling of ducted air, use a manometer
to measure the differential pressure created from air flow
across the sampling tubes. The pressure should measure no
less than 0.03 inches of water and no greater than 1.4 inches
of water. The air handler must be operating for this test.
[6.1.2] Smoke Response
To determine if smoke is capable of entering the sensing
chamber, visually identify any obstructions. Plug the ex-
haust and inlet tube holes to prevent ducted air from carry-
ing smoke away from the detector head, then blow smoke
such as cigarette, cotton wick, or punk directly at the head
to cause an alarm. REMEMBER TO REMOVE THE PLUGS
AFTER THIS TEST, OR THE DETECTOR WILL NOT FUNC-
TION PROPERLY.
[6.1.3] Filter Replacement
The filters do not substantially affect smoke performance
even when up to 90% of the filter is clogged. Quarterly vi-
sual inspection usually suffices to determine whether the
filters should be replaced because only a high percentage of
contamination affects performance. If further testing is re-
quired, compare differential pressure readings with and
without the filters installed. If the difference exceeds 10%
replace the filters. In no case should the pressure differen-
tial fall below 0.03 inches of water.
[6.2] Standby, Alarm, And Sensitivity Tests
[6.2.1] Standby And Trouble
Standby — Look for the presence of the flashing green
LED through the transparent housing cover.
The LED should flash approximately every
10 seconds.
Trouble — If the detector LED does not flash, then the
detector lacks power (check wiring, panel, or
power supply), the detector board is missing
(replace), or the unit is defective (return for
repair)
Test — The trouble condition can be caused inten-
tionally to verify correct operation of the sys-
tem. Remove the detector board to cause a
trouble condition locally and at the system
control panel.
Cover
Tamper — If the cover is removed for a period longer
than 20 minutes, a trouble signal is generated
to indicate the cover is missing.
[6.2.2] Alarm Tests
[6.2.2.1] M02-04-00 Magnet Test
1. Place the painted surface of the magnet onto the TEST
locator on the bottom of the housing (Figure 11).
2. The red alarm LED on the detector should latch on, as
should any accessories (i.e. RA400Z, RTS451). Verify
system control panel alarm status and control panel ex-
ecution of all intended auxiliary functions (i.e. fan shut-
down, damper control, etc.).
3. The detector must be reset by system control panel, front
cover reset button, or remote accessory.
D100-68-00 5 I56-1147-07