Distech Controls GS-SDD Series Manual

Hardware Installation Guide

GS-SDD Series

Duct Smoke Detectors

Figure 1: GS-SDD Series Duct Smoke Detectors

Product Description

This document describes the hardware installation procedures for the

GS-SDD Series duct smoke detectors. They are the latest innovation

for early detection of smoke and products of combustion present in air

moving through HVAC ducts in Commercial, Industrial and Residential

applications.

The GS-SDD Series, 4-wire duct housing will accommodate either the

ionization sensor or the photo electronic sensor. The interchangeable

detector heads allow easy removal for quick cleaning and

maintenance, or a change in application without removing the duct

housing.

The GS-SDD duct smoke detectors sample air currents passing

through a duct and give dependable performance for management of

fans, blowers, and air conditioning systems.

Output terminals are provided for remote accessories such as horns,

strobes, remote status indicators and test/reset key switches or push

buttons.

These duct smoke detectors include many features that represent true

innovations from current generation duct smoke detectors. It is

designed and built to meet all local requirements, as well as the NFPA

regarding duct smoke detectors.

All detectors must be used with a metal sampling tube, model GS-STxx

Series.

Figure 2: GS-STxx Series Sampling Tubes

General Installation Requirements

For proper installation and subsequent operation of each device, pay

special attention to the following recommendations:

- Upon unpacking the product, inspect the contents of the carton for

shipping damages. Do not install damaged device.

- Avoid areas where corroding, deteriorating or explosive vapors,

fumes or gases may be present.

- Ensure that all equipment is installed according to local, regional,

and national regulations.

Personal injury or loss of life may occur if you do not follow a

procedure as specified.

Equipment damage or loss of data may occur if you do not

follow a procedure as specified.

Take reasonable precautions to prevent electrostatic

discharges to the controller when installing, servicing or

operating the controller. Discharge accumulated static

electricity by touching one’s hand to a well-grounded object

before working with the controller.

Mounting Instructions

For the correct installation of a duct smoke unit, please refer to the

NFPA 72E (Standard for Automatic Fire Detectors) and NFPA 90A

(Standard for Installation of Air Condition and Ventilation Systems.)

This detector is not intended for open area protection nor should it be

used for early warning detection or replace a regular fire detection

system.

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The GS-SDD duct smoke detectors are fitted with a mounting base that

will accept 2 models:

- Ionization Detector (GS-SDDI): 4 wire ionization smoke detector

(Listed for high temperature applications)

- Photoelectric Detector (GS-SDDP): 4 wire photoelectric smoke

detector

The duct unit supports 2 sets of form “C” and 1 form “A” Alarm

Contacts and 1 form “C” Trouble Contact. The trouble contact

supervises the presence of the input power and removal of the

detector head.

The trouble contacts (terminals 4-15-5) are shown in the non-

energized condition.

The trouble contact will not operate in the event of a smoke alarm.

The GS-SDD Series will operate on one of the following input voltage

sources: 24VAC, 24VDC, 115VAC and 230VAC.

The duct smoke detector units are designed to operate in duct widths

from 12 inches to 10 feet wide with an air velocity between 100 and

4,000 feet per minute. To verify correct installation, the pressure

differential between the input and exhaust tubes should be measured

using a Magnehelic pressure gauge or equivalent. An acceptable

reading must be between 0.01 and 1.2 inches of water.

For a Smoke Duct Detector unit to operate correctly, it must be

installed 6 duct widths from any obstruction i.e. elbows, deflector

plates, filters, dampers, etc. In situations where the criteria cannot be

met, deviations are acceptable providing they meet the pressure

differential requirements.

Sampling Tubes

The principal of operation of a duct detector is based on the Venturi

effect. Two tubes extend into the HVAC duct. Air flowing through the

duct is forced into the air intake tube via the air intake holes, and

passes over the detector head. The air will be drawn out via the

exhaust tube back into the HVAC duct. (7” exhaust tube provided in

the installation kit.) When the particles of smoke suspended in the air

stream reach the alarm threshold of the detector head, the unit will go

into alarm.

Duct Unit Installation

Duct Smoke Location Prerequisites

This guideline contains general information on duct smoke detector

installation, but does not preclude the NFPA documents listed.

Distech Controls assumes no responsibility for improperly installed

duct detectors. To determine the correct installation position for a GS-

SDD Series Duct Smoke Detector, the following factors must be

considered.

1. A uniform non turbulent airflow of between 100 ft/min to 4,000

ft/min. must be present in the HVAC duct. To determine the

duct velocities examine the engineering specifications that define

the expected velocities or use an Alnor model 6000P velocity/meter

(or equivalent).

2. In order to prevent stratification, duct smoke units, where possible,

must be located a minimum of six duct widths downstream from a

source of turbulence (i.e. elbows, deflector plates, filters, dampers,

and inlets). In installations where it is impossible to adhere to the

six duct width requirement, units can be installed closer but as far

from inlets, bends or deflector plates as possible. Should this

situation arise, check velocity readings in the duct prior to the duct

smoke unit installation. Ensure the duct smoke unit pressure

differential complies with the unit specifications. The pressure

differential between the input sampling tube and exhaust tube for

the GS-SDD series duct smoke unit should be greater than 0.01

inches of water and less than 1.2 inches of water.

3. Identify a location for the installation of the duct unit that will permit

easy access for viewing and serviceability.

4. Install duct units in the return air side of an HVAC unit prior to the

air being exhausted from the building or diluted with outside air.

5. When installing duct smoke units down stream of filters, fires

occurring in the filters will be detected, but If the filters become

blocked insufficient air flow through the duct unit will prevent the

correct operation of the duct detector.

6. Where possible, install duct detectors upstream of air humidifiers

and downstream of dehumidifiers.

7. To prevent false alarms, the duct detector should not be mounted

in areas of extreme high or low temperatures, in areas where high

humidity exists or in areas where the duct may contain gases or

excess dust.

Figure 3. Duct Unit Installation.

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Sampling Tube Assembly

Sampling tubes are to be ordered separately in one of the 4 standard

lengths.

Model

Description

GS-ST01:

Sampling tube duct widths 1' - 2' (10")

GS-ST02:

Sampling tube duct widths 2' - 4' (2.5')

GS-ST05:

Sampling tube duct widths 4' - 8' (5.0')

GS-ST10:

Sampling tube duct widths 8' - 12' (10.0')

The standard sampling tubes are steel tubes with air intake holes

drilled down the entire length of the tube. These tubes must be cut to

length and must span the entire width of the duct. Sampling tubes over

3.0 feet must be supported on the opposite side of the duct. To ensure

the correct operation of the sensing tube, the red end cap (red stopper

in installation kit) must be inserted in the end of the air intake sampling

tube.

Duct Preparation

For ease of duct unit installation, remove mounting template from the

installation kit. Remove paper backing from the mounting template and

affix it to the duct at the desired location. Using the template as a

guide, drill 2 mounting holes (3/32” diam.) for the 12 X 1/2” sheet metal

screws packaged in the installation kit.

Drill or punch 1 1/4” holes for sampling tubes, using the template as a

guide. Clean all holes.

Mounting Duct Smoke Detector

Mount the housing to the duct using 2 #12 x 1/2” sheet metal screws.

Install the intake tube making sure the holes are facing the air flow.

Tighten the latch screw to secure the tube. Install the exhaust tube.

Tighten the latch screw to secure the tube.

Air Sampling Verification

To ensure correct operation of the duct unit use a Magnehelic

differential pressure gauge or Dwyer model 4000 to determine the

differential pressure between the inlet and exhaust tubes. The

differential pressure between the two tubes should be greater than

0.01 inches of water and less than 1.2 inches of water.

This duct smoke detector is shipped with a separate velocity adapter

insert, found in the installation kit.

Installing this adapter will allow the duct detector to operate at

extremely low air velocities - outside of the range referred to in the

attached installation instructions.

To use the adapter, simply insert it into the slots provided inside the

detector housing so that the adapter fits snugly over the smoke

detector head. Unless your system is consistently operating in the

slower velocity range, we recommend that the adapter not be inserted.

If you experience false alarms at higher velocities with the adapter in

place, the adapter should be removed.

Please use the following chart for guidance on when the velocity

adapter should be used. For reference, the speeds indicated are

intended to represent the velocity of air within the duct under normal

operational conditions.

Figure 4. Chart for Guidance on When Velocity Adapter Should be Used.

Electrical Installation

Wiring

Prior to connecting power to the GS-SDD duct units, determine the

correct input voltage and ensure it is connected to the correct

terminals. (Refer to Terminal Connections).

24VAC/DC,Terminals (9, 10);

115VAC, Terminals (115, H, G);

230VAC, Terminals (220, H, G).

Terminal Connections

Figure 5. Terminal Connections.

For terminals (7, 8, 18), (6, 16, 17), (13, 14) do not use

looped wire under terminals. Break wire run to provide

supervision of connections. To test the correct operation of

the duct smoke unit, excluding the detector head (see Test

Procedures) remove detector head and connect one of the

appropriate dedicated power sources to the applicable

terminals (See above). Replace detector head and cover,

the unit will be energized (The green LED will be

illuminated). When pressing the test/reset button the red

alarm LED will be illuminated. In the event of a fire alarm,

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certain equipment may have to be shut down. A shutdown

will be achieved by interrupting the supply source to that

particular piece of equipment when wired as indicated in

Figure 6.

Figure 6. Wiring Example.

Test Procedures

Operational Testing

To determine the correct operation of the GS-SDD Duct Smoke

Detectors, ensure power is connected and the green pilot LED is

illuminated.

The LED on the detector head flashes during the standby mode. The

LED on the detector head will be permanently illuminated when smoke

is detected and the head is in alarm.

With the air handling unit shut down, and the clear cover removed,

press and hold the test/reset button and the cover removal switch on

the GS-SDD Duct Unit. The red alarm LED on the circuit board will be

illuminated and the alarm relay outputs will change state. Using a multi

meter set to OHMS (or continuity buzzer function on the meter) place

the meter probes on the following terminals and ensure the contacts

are closed (continuity) (18, 8), (6,17) when releasing the test/reset

button these contacts will open.

Functional Testing

Once operational, testing is concluded, the unit requires functional

testing to determine the correct operation of the detector head.

Magnet Testing

Place the magnet provided with the instruction kit on top of the housing

between the raised sections above the detector head (as indicated on

the unit cover). Allow at least five (5) seconds for alarm initiation.

Remove magnet and reset detector.

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Smoke Testing

Using smoke test canister with testing nozzle, insert the test gas

nozzle into the test point on the unit cover. Press can against cover to

release gas into chamber.

Do not spray gas for more than 1/2 second. Overuse of test

gas facility will result in detector contamination.

After 15 to 20 seconds the detector head will go into alarm, illuminating

the detector head LED and causing the duct unit functions to operate,

relays will change state and the remote accessories if attached will

function. Please allow several minutes for the gas to evacuate the

chamber before the detector may be reset.

If no test gas is available to conduct the testing, remove cover and,

while holding the cover removal switch, blow smoke from a cotton wick

or punk directly at the head to cause alarm. The alarm indicator will

illuminate within one minute.

Should testing be required for simulated fire conditions, smoke bombs

placed in the duct may not be suited for the particular detector head

selected and installed.

Ionization Detector (GS-SDDI) utilizes a radioactive source as its

means of detection and will detect smoke particles of between .1 and 1

micron in size.

Photoelectric Detector (GS-SDDP) operates on the principle of light

scatter and will detect smoke particles of between 1 and 10 microns in

size.

When purchasing smoke bombs for functional testing, ensure smoke

particle sizes comply with the criteria as described above.

Maintenance

Each installation location must be assessed on its own merits. If the

protected area is of a very dirty nature then the GS-SDD Duct units will

have to be checked and cleaned on a quarterly basis or when cleaning

is required.

As a guideline the detector head should be cleaned every six (6)

months or as required. The best methods of cleaning are to vacuum

the detector head thoroughly or to blow the detector head out using

compressed air. Do not use chemicals to clean the detector head

housing as this could contaminate the detector head and damage the

casing. Sensing tubes must be inspected and cleaned in accordance

with the schedule as determined above, to allow the free flow of air

through the sensing tube.

Dimensions

Figure 7. Dimensions for the GS-SDD Series Duct Smoke Detectors

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Remote Accessory Wiring

Figure 8.

Figure 9.

Fire Alarm Control Panel Wiring

Figure 10.

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Figure 11.

While all efforts have been made to verify the accuracy of information in this manual, Distech Controls is not responsible for damages or claims arising from the use of this

manual. Persons using this manual are assumed to be trained HVAC specialist / installers and are responsible for using the correct wiring procedures and maintaining safe

working conditions with fail-safe environments. Distech Controls reserves the right to change, delete or add to the information in this manual at any time without notice.

Distech Controls, the Distech Controls logo, and Innovative Solutions for Greener Buildings are trademarks of Distech Controls Inc. All other trademarks are property of their

respective owners.

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GS-SDD Series_IG_10_EN

Detector Interconnection Wiring Common Functions

Figure 12.

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