For signal wiring, (the wiring between interconnected
detectors or from detectors to auxiliary devices), it is usu-
ally recommended that single conductor wire be no small-
er than 18 gauge. The duct smoke detector terminals
accommodate 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.
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 DH100LP 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 DH100LP duct smoke detector is designed to operate
with 12 or 24 VDC UL listed 2-wire compatible control pan-
els. Alarm current must be limited by the control panel to
100mA or less. An example of a UL listed compatible con-
trol panel is the Fire-Lite model Sensiscan 1000 using zone
card ANC-2 and compatibility identification “A”. Install per
installation instruction S1000/801. A maximum of 20 detec-
tors may be installed per zone.
[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 six 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 six screws.
[6] Duct Smoke Detector Maintenance And Test
Procedures
Test and maintain duct smoke detectors 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.
[6.1] Smoke Entry Tests
[6.1.1] Air Flow
The DH100LP is designed to operate over an extended air
speed range of 100 to 4000 FPM. To verify sufficient sampling
of ducted air, turn the air handler on and use a manometer to
measure the differential pressure between the two sampling
tubes. The differential pressure should measure at least
0.0015 inches of water and no more than 1.2 inches of water.
Because most commercially available manometers cannot
accurately measure very low pressure differentials, applica-
tions with less than 500 FPM of duct air speed may require
one of the following: 1) the use of a current-sourcing pressure
transmitter (Dwyer model numbers 607-1 or 607-01) see field
bulletin Z75-79-00 or; 2) the use of aerosol smoke per sec-
tion 6.1.2.
[6.1.2] Air Flow Test using Aerosol Smoke
Drill a 1⁄4″hole 3 feet upstream from the duct smoke detec-
tor. With the air handler on, measure the air velocity with
an anemometer. Air speed must be at least 100 FPM. If the
air speed is greater than 500 FPM, use a conventional
manometer to measure differential pressure between the
sampling tubes. Spray aerosol smoke* into the duct through
the 1⁄4″hole for five seconds. Wait two minutes for the duct
smoke detector to alarm. If the duct smoke detector alarms,
air is flowing through the detector. Remove the duct smoke
detector cover and blow out the residual aerosol smoke from
the chamber and reset the duct smoke detector. Use duct
tape to seal the aerosol smoke entry hole.
*Aerosol smoke can be purchased from Home Safeguard Industries,
Malibu, CA. Phone: 310/457-5813.
To determine if smoke is capable of entering the sensing
chamber, visually identify any obstructions. Plug the
exhaust and inlet tube holes to prevent ducted air from car-
rying 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
visual inspection usually suffices to determine whether the
filters should be replaced because only a high percentage of
contamination affects performance. If further testing is
required, 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 0.0015 inches of water.
D200-15-00 5 I56-0083-00
