Edwards SIGA-SDH Duct Detector Housing with Standard Base

The Edwards SIGA-SDH Duct Detector Housing with Standard Base is a Signature Series housing designed to adapt compatible Edwards intelligent smoke detectors for use in HVAC duct smoke detection applications. The housing includes a standard detector base installed and prewired at the factory, allowing a compatible Signature detector head to be installed directly into the assembly.

The SIGA-SDH samples air moving through HVAC ductwork so the installed intelligent detector can identify smoke within the airstream and communicate the condition to the compatible Edwards fire alarm system. Edwards offers the related SIGA-SDHR when a relay-base configuration is required instead of the standard base supplied with the SIGA-SDH.

Product Functions

• Houses compatible Edwards Signature Series intelligent detectors
• Provides HVAC duct smoke detection
• Includes a factory-installed standard detector base
• Detector base is prewired inside the housing
• Accepts compatible intelligent photoelectric detector heads
• Supports compatible multisensor detector applications
• Allows standard Signature detector technology to be used in duct applications
• Supports duct airflow up to 4,000 FPM with compatible detector configurations
• Supports HVAC ducts up to 10 feet wide
• Uses interchangeable sampling tubes
• Includes an exhaust tube
• Supports remote LED indication
• Supports compatible remote testing accessories
• Provides a removable access cover for detector servicing
• Uses rugged metal enclosure construction
• Provides mounting provisions for compatible Signature modules
• Designed for intelligent addressable fire alarm systems

Duct Smoke Detection

The primary function of the SIGA-SDH is to allow an Edwards Signature Series detector to monitor air moving through an HVAC duct.

A sampling tube extends into the duct and collects air from the airstream. The sampled air passes through the housing and across the installed smoke detector before being returned to the duct.

If the installed detector senses smoke at its programmed alarm threshold, it communicates the condition to the compatible Signature fire alarm system. The control panel can then initiate programmed responses such as HVAC shutdown, fan control, smoke-control functions, alarm annunciation, or other life-safety operations.

The actual alarm response is determined by the installed detector, fire alarm system programming, and approved sequence of operations.

Standard Detector Base

The SIGA-SDH includes a standard detector base, distinguishing it from the SIGA-SDHR relay-base version.

The standard base is installed and prewired inside the duct housing at the factory.

SIGA-SDH vs. SIGA-SDHR

Edwards provides two primary versions of this duct housing:

• SIGA-SDH – Duct detector housing with standard detector base
• SIGA-SDHR – Duct detector housing with relay base

The SIGA-SDH is appropriate when the application requires intelligent duct detection without the integral relay-base functionality supplied with the SIGA-SDHR.

Signature Series Detector Compatibility

The SIGA-SDH is designed to accept compatible Signature Series intelligent smoke detectors.

This allows the duct installation to benefit from the intelligent processing and addressable communication features of the selected detector rather than relying on a simple conventional duct sensor.

Compatible detector types can include supported:

• Photoelectric smoke detectors
• Photoelectric/heat multisensors
• Other Signature detector configurations documented for the housing

Compatibility depends on the detector generation and fire alarm control equipment and should be verified against Edwards documentation for the exact system.

Intelligent Addressable Operation

The SIGA-SDH housing itself provides the mechanical duct-sampling platform, while the installed Signature detector provides the intelligent addressable detection functions.

The detector communicates with the compatible Signature loop controller and can provide point-specific alarm identification through the fire alarm control system.

Signature Series detection technology is designed around intelligent device processing and addressable communication, allowing the detector to participate in system diagnostics, alarm reporting, and programmed life-safety functions.

Air Velocity

The SIGA-SDH supports HVAC applications with air velocities up to approximately:

Maximum Air Velocity: 4,000 ft/min / 20.3 m/s

The actual allowable airflow range depends on the specific detector installed in the housing.

Airflow should be measured and verified during installation so the detector housing operates within the approved limits for the selected detector.

Duct Width

The SIGA-SDH can be installed on HVAC ducts up to approximately:

Maximum Duct Width: 10 ft / 3.05 m

Different sampling tube lengths are available so the detector can be matched to the width of the duct.

Proper sampling tube selection is necessary to ensure representative air sampling across the duct.

Sampling Tubes

The SIGA-SDH uses interchangeable sampling tubes selected according to duct width.

Available tube lengths documented for the product family include approximately:

• 8 in
• 2 ft
• 3 ft 6 in
• 6 ft 6 in
• 10 ft

The sampling tube is ordered separately from the SIGA-SDH housing.

The tube must be installed with its sampling openings facing into the direction of airflow so air is properly drawn through the detector housing.

Exhaust Tube

The SIGA-SDH includes an exhaust tube used to return sampled air from the detector housing back into the HVAC duct.

The documented exhaust tube length is approximately:

6 in / 150 mm

Correct installation of both the inlet sampling tube and exhaust tube creates the pressure differential required to move duct air through the detector chamber.

Remote LED & Test Accessories

The SIGA-SDH supports compatible remote annunciation and testing accessories.

These accessories are particularly useful when the duct detector is installed:

• Above suspended ceilings
• In mechanical rooms
• On elevated ductwork
• In restricted-access areas
• Where the detector housing cannot be easily observed

Remote indication can provide visible detector status, while remote test equipment can allow functional testing from a more accessible location.

Housing Construction

The SIGA-SDH uses a rugged metal enclosure designed for HVAC duct installations.

Published product information identifies:

Construction: 16-gauge steel
Finish: Red baked enamel

The red finish makes the housing readily identifiable as part of the building fire alarm system.

A removable access cover provides access to the detector, wiring, detector base, and interior smoke chamber for installation and maintenance.

Module Mounting Provisions

The SIGA-SDH housing provides multiple knockouts that can be used for compatible Signature module installations where required.

Edwards documentation identifies five module knockouts on the housing.

These provisions can simplify applications that require an addressable relay, control module, or other compatible function near the duct detector.

The exact module and wiring arrangement must follow Edwards installation requirements.

Field Wiring

The prewired detector base supports common fire alarm conductor sizes.

Compatible conductor sizes include:

18 AWG
16 AWG
14 AWG
12 AWG

The actual wiring method depends on the detector, Signature loop configuration, remote accessories, and any additional modules installed with the housing.

Installation Information

Typical SIGA-SDH installation includes:

• Selecting a suitable location on the HVAC duct
• Confirming direction of airflow
• Measuring the duct width
• Selecting the correct sampling tube
• Drilling the required mounting and tube openings
• Securing the housing to the duct
• Installing the inlet sampling tube
• Installing the exhaust tube
• Connecting Signature loop wiring
• Installing the compatible detector head into the standard base
• Connecting remote LED or test accessories where required
• Verifying duct air velocity
• Testing smoke detection
• Confirming the programmed HVAC or fire alarm response

The housing should be located where airflow is reasonably uniform and away from severe turbulence where practical.

Not a Complete Smoke Detector

The SIGA-SDH is a duct detector housing with a standard base, not a complete smoke detector by itself.

The housing includes:

• Duct detector enclosure
• Standard detector base
• Prewired internal connections
• Exhaust tube

A compatible Signature Series detector head and appropriately sized sampling tube are selected separately.

This distinction is important when ordering replacement equipment.

Not a Substitute for Open-Area Detection

Duct smoke detection is intended to detect smoke being transported through an HVAC system.

It does not automatically replace required open-area smoke detectors installed throughout the protected building.

Open-area detection requirements should continue to be determined by the approved fire alarm design, applicable codes, and authority having jurisdiction.

Testing & Maintenance

Testing should confirm:

• Correct detector identification at the fire alarm control panel
• Proper Signature loop communication
• Secure detector installation in the base
• Correct sampling tube size
• Correct sampling tube orientation
• Proper exhaust tube installation
• Adequate airflow through the housing
• Proper smoke detection
• Correct remote LED indication where installed
• Correct remote test operation where installed
• Proper HVAC shutdown or other programmed response
• Secure field wiring
• Secure housing attachment
• Proper system restoration after testing

Product Identification

• Manufacturer: Edwards
• Model: SIGA-SDH
• Series: Signature Series
• Product Type: Duct Detector Housing with Standard Base
• Primary Function: HVAC Duct Smoke Detection
• Detector Included: No
• Detector Base Included: Yes
• Base Type: Standard
• Base Installation: Factory installed and prewired
• Relay Base: No
• Relay Version: SIGA-SDHR
• Detector Type: Compatible Signature Series detector
• Maximum Air Velocity: Up to 4,000 FPM with compatible detector
• Maximum Duct Width: 10 ft / 3.05 m
• Sampling Tube: Ordered separately
• Maximum Sampling Tube Length: 10 ft
• Exhaust Tube: Approximately 6 in included
• Remote LED Support: Yes
• Remote Test Support: Yes
• Construction: 16-gauge steel
• Finish: Red baked enamel
• Module Knockouts: 5
• Wire Size: 12–18 AWG
• Application: Intelligent HVAC duct smoke detection

Protection & Applications

Suitable for:

• Commercial Fire Alarm Systems
• Edwards Signature Series Systems
• Intelligent Addressable Fire Alarm Systems
• HVAC Duct Smoke Detection
• Supply Air Ducts
• Return Air Ducts
• Air Handling Units
• HVAC Shutdown Applications
• Smoke Control Systems
• Mechanical Rooms
• Office Buildings
• Hospitals and Healthcare Facilities
• Schools and Universities
• Hotels
• Government Buildings
• High-Rise Buildings
• Data Centers
• Industrial Facilities
• Warehouses
• Manufacturing Facilities
• Institutional Facilities
• Commercial Life Safety Systems

Its factory-prewired standard base, support for ducts up to 10 feet wide, high-airflow capability, interchangeable sampling tubes, and remote accessory support make it a flexible platform for intelligent duct smoke detection.

Download the Specification sheet in *.pdf format