Installation: Honeywell HFS-D Duct Smoke Detector Instruction Manual

Overview

The HFS-D Duct Smoke Detector is an addressable, photoelectric detector designed to monitor smoke moving through heating, ventilation, and air-conditioning ductwork. It samples air from the duct and reports a developing smoke condition to a compatible fire alarm control panel.

This device is intended for duct smoke detection and HVAC system control functions such as fan shutdown, damper operation, or air-handling changes. It is not a replacement for open-area smoke detectors or the building’s primary life-safety fire alarm coverage.

The sensor head is factory installed. A separate sampling tube must be selected for the duct width before installation.

Specifications

• Model: HFS-D
• Factory-installed sensor head: HFS-DPR
• Detection method: Photoelectric
• Operating voltage: 15 to 32 VDC
• Standby current: 300 μA at 24 VDC with LED blinking enabled
• Maximum alarm current: 6.5 mA at 24 VDC with LED on
• Operating temperature: –4°F to 158°F (–20°C to 70°C)
• Operating temperature with module installed: 32°F to 120°F (0°C to 49°C)
• Storage temperature: –22°F to 158°F (–30°C to 70°C)
• Humidity: 0% to 93% relative humidity, non-condensing
• Supported air velocity: 100 to 4000 feet per minute (0.5 to 20.3 m/s)
• Supported duct width: 6 inches to 12 feet
• Rectangular footprint: 14.38 × 5 × 2.5 inches (37 × 12.7 × 6.36 cm)
• Square footprint: 7.75 × 9 × 2.5 inches (19.7 × 22.9 × 6.35 cm)
• Weight: 1.8 pounds (0.82 kg)
• Accessory alarm current: up to 12 mA at 24 VDC

Contents

The HFS-D duct smoke detector kit contains the sensor and power-board assembly with covers, a factory-installed sensor head, three number 10 sheet-metal mounting screws, a test magnet, a drilling template, a sampling-tube end cap, and a plastic exhaust tube.

The sampling tube is ordered separately. Select its length according to the duct width so the inlet section extends at least two-thirds across the duct.

Detailed Description

Air entering the duct passes through the sampling tube and detector housing. The HFS-D photoelectric sensor evaluates the sampled air for smoke particles. When the smoke level reaches the detector’s alarm threshold, the connected fire alarm panel can initiate programmed responses for the affected air-handling equipment.

The housing supports either a side-by-side rectangular arrangement or a top-over-bottom square arrangement. The sensor head uses rotary code switches for address selection. The detector also includes a cover-tamper feature: removing or incorrectly fitting the sensor cover produces a trouble condition at the panel.

Two LEDs on the sensor head can provide local status indication when enabled by the control panel. The housing supports remote alarm indication and remote testing with compatible accessories. An approved relay or control module may also be installed inside the power-board side of the housing when the fire alarm system requires that function.

Safety

• Do not use a duct detector as a substitute for open-area smoke detection, early-warning detection, or required building life-safety protection.
• The detector cannot operate without electrical power. Fire conditions may interrupt power, so the complete fire protection design must include appropriate safeguards.
• The ventilation system must be operating and the detector cover must be correctly installed for smoke to reach the sensor.
• Install and operate the device only within the electrical, environmental, and airflow limits specified for the detector and sensor head.
• Disconnect power from the communication line before wiring or servicing the detector.
• Follow applicable electrical and fire-alarm codes, including requirements for duct detector placement, wiring, testing, and maintenance.
• Notify the responsible authorities before testing or servicing. Disable the affected zone or system to prevent unwanted alarms or an unnecessary emergency response.
• Use caution with canned aerosol smoke. Excessive or incorrect use may affect the sensing chamber.

Installation

Check the duct conditions

Confirm the airflow direction and verify that the duct velocity is between 100 and 4000 feet per minute. Use an anemometer when the actual velocity is unknown. On ducts wider than 18 inches, mounting downstream of a bend, obstruction, or supply or return inlet is recommended. Local codes may permit installation in supply or return sections of packaged rooftop systems, fire and smoke dampers, and economizers.

Select the housing configuration

Choose the rectangular side-by-side or square top-over-bottom configuration based on the available mounting space. To change to the square arrangement, remove the rear attachment screw, pivot the housing at its hinge, and reinstall the screw in the alternate mounting hole. Do not remove the hinge screw.

Drill the mounting holes

Place the supplied template flat against the duct at the selected location. For either configuration, mark the two sampling-tube positions and cut two 1⅜-inch holes. Use a 5⁄32-inch drill for the mounting holes marked for the selected housing arrangement.

Use two supplied screws for rectangular mounting or three supplied screws for square mounting. Tighten the screws securely without overtightening them.

Sampling Tube Installation

Select the tube

• Ducts up to 1 foot: DST1
• Ducts from 1 to 2 feet: DST1.5
• Ducts from 2 to 4 feet: DST3
• Ducts from 4 to 8 feet: DST5
• Ducts from 8 to 12 feet: DST10, two-piece construction

The recommended tube should reach at least two-thirds across the duct. Install the tube with its inlet holes facing into the airflow. The arrow on the connector identifies the correct airflow direction.

Install the tube and end cap

For a tube shorter than the duct width, slide it into the housing connection that meets the airflow first and fit the supplied end cap to the opposite end. For tubes longer than the duct, drill a ¾-inch opening in the opposite duct wall and allow the tube to pass through.

Angle a tube that passes through the opposite wall downward toward the far end so moisture drains away from the detector. Use a downward slope of at least ¼ inch for each 12 inches of duct width. Leave approximately 1 to 2 inches outside the duct, seal the exposed end with the end cap, and close any exposed holes. Seal the opening around the tube.

The sampling tube should normally have 10 to 12 inlet holes distributed as evenly as possible across the airflow. In ducts wider than 8 feet, join the tube sections inside the duct with the supplied ½-inch conduit fitting and support the far end when required.

If a long tube vibrates excessively, a suitable floor flange may be used to secure its far end. The plastic exhaust tube is installed in the housing connection downstream from the sampling tube. A longer exhaust tube may be needed when the supplied tube does not extend at least 2 inches into the duct.

Remote tube arrangements

A remote sampling tube or exhaust tube may be used when the detector housing cannot be mounted directly at the sampling point. Rigidly secure the detector and tubes against airflow pressure and vibration. Position the sampling tube where airflow is uniform across the duct and verify the pressure difference between the sampling and exhaust ports.

Measurement Tests

Differential pressure test

Turn on the air handler and use a manometer to measure the pressure difference between the sampling and exhaust ports. The acceptable differential pressure is 0.01 to 1.11 inches of water. Final installation approval should be based on successful pressure and smoke-entry testing.

Very low airflow applications may require a pressure transmitter because many handheld manometers cannot accurately measure small differentials. The duct velocity must still be at least 100 feet per minute.

Low-flow transmitter method

Verify duct velocity with an anemometer. Connect a suitable current-sourcing differential-pressure transmitter and a 1000-ohm resistor according to the system wiring arrangement. Allow the transmitter to warm up for 15 seconds, then record the voltage with both pressure ports open to ambient air.

Connect the transmitter high side to the detector sampling tube and the low side to the exhaust tube. Record the second voltage and subtract the first reading. A difference greater than 0.15 volts indicates sufficient airflow through the detector for proper operation.

Field Wiring and Addressing

Install all wiring according to applicable electrical codes and the control-panel manufacturer’s signaling-line requirements. Use properly sized, color-coded conductors. Signal wiring is commonly no smaller than 18 AWG, while the detector terminals accept conductors up to 12 AWG. Flexible conduit is recommended for the final foot of the conduit run.

The terminal strip uses clamping plates. Insert the stripped conductor beneath the plate and tighten the terminal screw. Connect the detector to a compatible listed fire alarm control panel, observing communication-line polarity.

Before connecting the loop, disconnect power from the communication line. Set the detector address using the rotary code switches on the back of the sensor head.

Keep the supplied sampling-tube end cap installed after making any tube adjustment. The cap is necessary for the intended airflow through the detector.

Setup and Operation

Install the covers

Check that the sensor-cover gasket is seated correctly. Fit each cover into the housing groove and tighten the seven captured screws. The detector cover must be installed correctly for normal operation and for the cover-tamper circuit to clear.

Power and status check

Activate the communication line through the positive and negative communication terminals. When programmed by the control panel, the sensor LEDs flash with each communication during standby.

If the LEDs do not flash, check the communication wiring, power supply, panel programming, sensor-head installation, and cover fit. A missing sensor head, an improperly installed cover, insufficient power, or a defective detector can also produce a trouble condition.

Functional testing

Use the supplied test magnet to electronically simulate smoke in the sensing chamber. Confirm that the control panel receives the alarm and performs all programmed auxiliary actions, such as fan shutdown or damper control.

A compatible remote test station can provide another method of initiating an alarm test. Remote-test wiring must be limited to 25 ohms or less per interconnecting wire, and the required resistor assembly must be installed inside the HFS-D for the remote-test function to operate.

After an alarm test, reset the detector from the system control panel. Test the complete duct smoke detection system according to the maintenance requirements for the fire alarm installation.

Aerosol smoke entry test

For systems operating from 100 to 500 feet per minute, drill a ¼-inch test hole 3 feet upstream from the detector. With the air handler running, confirm that velocity is at least 100 feet per minute. Spray simulated smoke through the hole for five seconds and wait up to two minutes for an alarm.

After a successful test, remove the detector cover, clear residual aerosol from the sensing chamber, reset the detector at the panel, and seal the test hole with duct tape. Reinstall the cover before returning the system to service.

Cleaning and Maintenance

Test and maintain the HFS-D Duct Smoke Detector at regular intervals required by the applicable fire alarm standard. The detector should be cleaned at least once each year and whenever dust or contamination may affect sampling.

Before maintenance, notify the responsible authorities and disable the affected zone or system. Remove the sensor head from service, then press the four cover-release tabs to remove the sensor cover.

1. Carefully vacuum the sensor screen without removing it.
2. If additional cleaning is needed, pull the chamber cover and screen assembly straight out.
3. Use a vacuum cleaner or clean compressed air to remove dust and debris from the sensing chamber.
4. Slide the chamber cover and screen assembly back over the chamber and turn it until firmly seated.
5. Align the sensor cover using the LEDs and press it into place until it locks.
6. Reinstall the sensor head in the detector housing.
7. Restore system power and perform a detector check.
8. Notify the responsible authorities that maintenance is complete and the system is operational.

Sensor Replacement

To remove the sensor head, rotate it counterclockwise and pull it gently from the housing. Install the replacement by aligning its mounting features and rotating it clockwise until secured. Confirm the address setting and perform a detector check after replacement.

Optional Accessories

• RA400Z or RA100Z remote alarm LED annunciator
• RTS451 or RTS151 remote test station
• RTS451KEY or RTS151KEY keyed remote test station
• Compatible relay or control module installed inside the power-board section

When using a remote alarm indicator, keep the blue wire connected to the RA+ terminal on the field-connector side. For an RA400Z, break the designated tab for use with the intelligent duct detector. For an RA100Z, remove the jumper as required by the accessory wiring arrangement.

Troubleshooting

• No LED communication: Check loop polarity, wiring continuity, power, panel programming, sensor-head seating, and cover installation.
• Cover trouble remains active: Confirm that the cover gasket is seated, the cover is fully engaged in the base groove, and all captured screws are tightened.
• Insufficient airflow: Verify that the air handler is operating, the sampling tube arrow faces into the airflow, the exhaust tube is downstream, the end cap is installed, and the pressure differential is within range.
• Detector does not alarm during smoke testing: Confirm that the duct velocity is at least 100 feet per minute, the test smoke reaches the sampling tube, the sensor head is correctly installed, and the panel has not disabled the zone.
• Unexpected alarm or unstable operation: Inspect the sampling and exhaust tubes for blockage, leakage, vibration, incorrect orientation, or excessive contamination. Clean the sensor and repeat the airflow test.
• Remote test does not operate: Verify accessory compatibility, wiring resistance, terminal connections, and the required resistor assembly inside the detector.

Warranty

The HFS-D is covered by a limited three-year warranty from the date of manufacture against defects in materials and workmanship under normal use and service. The stated coverage does not extend to damage caused by unreasonable use, modifications, alterations, or other conditions outside normal service.

Pros and Cons

Pros

• Supports both rectangular and square mounting layouts.
• Works across a broad duct-air-velocity range.
• Uses a factory-installed plug-in photoelectric sensor head.
• Provides address selection, cover tamper supervision, local LED indication, and remote testing.
• Accommodates duct widths from 6 inches to 12 feet with the appropriate sampling tube.

Cons

• A sampling tube must be selected and purchased separately.
• Correct airflow direction, pressure testing, and tube positioning are essential for dependable operation.
• The device requires a functioning ventilation system and electrical power to detect smoke in the duct.
• It cannot replace open-area smoke detectors or the building’s required fire alarm protection.