System Sensor D4120 Duct Smoke Detector & D4S Sensor Component Installation and Maintenance Instructions

Specifications

NOTE: Alarm auxiliary contacts shall not be connected to initiating circuits of control panels. Use the alarm initiation contact for this purpose.

Limitations of Duct Smoke Detectors

WARNING: The National Fire Protection Association has established that DUCT DETECTORS MUST NOT BE USED AS A SUBSTITUTE FOR OPEN AREA DETECTOR PROTECTION as a means of providing life safety. Nor are they a substitute for early warning in a building's regular fire detection system.

System Sensor supports this position and strongly recommends that the user read NFPA Standards 90A, 72, and 101. The D4120 Air Duct Smoke Detectors are listed per UL 268A.

This device will not operate without electrical power. Fire situations may cause an interruption of power. The system safeguards should be discussed with your local fire protection specialist.

This device will not sense smoke unless the ventilation system is operating and the cover is installed.

For this detector to function properly, it MUST be installed according to the instructions in this manual. Furthermore, the detector MUST be operated within ALL electrical and environmental specifications listed in this manual. Failure to comply with these requirements may prevent the detector from activating when smoke is present in the air duct.

General Description

Smoke introduced into an air duct system will be distributed throughout the entire building. Smoke detectors designed for use in air duct systems are used to sense the presence of smoke in the duct.

Model D4120 and D4S Duct Smoke Detectors utilize 4-wire photoelectric technology for the detection of smoke. This detection method, when combined with an efficient housing, samples air passing through the duct allowing detection of a developing hazardous condition. When sufficient smoke is sensed, an alarm signal is initiated and appropriate action can be taken to shut off fans, blowers, change over air handling systems, etc. These actions can facilitate the management of toxic smoke and fire gases throughout the areas served by the duct system.

The D4120 and D4P120 detectors are designed to operate on 24 VDC/VAC or 120 VAC. Alarm and supervisory relay contacts are available for control panel interface (alarm initiation), HVAC control, and other auxiliary functions. Auxiliary relays are provided for fan shut down. Detector interconnection provides signaling of up to 50 other detectors in the loop for multiple fan shut down. These detectors are not designed for 2-wire applications.

Detector Feature Set

• Utilizes 2D51 plug-in head
• 2 sensors to 1 power board capability
• Cover missing signal
• Sampling tubes install from front or rear of detector
• Compatible with existing accessories

Contents of the Duct Smoke Detector Kit

1. Sensor/power board assembly and cover(s)
2. Three #10 sheet metal screws for mounting
3. One test magnet
4. Drilling template
5. One sampling tube end cap
6. One plastic exhaust tube

NOTE: A sampling tube must be ordered to complete the installation. It must be the correct length for the width of the duct where it will be installed. See Table 1 on page 3 to determine the inlet tube required for different duct widths.

Detector Installation

Verify Air Flow Direction and Velocity

Model D4120 detectors are designed for air handling systems with air velocities of 100 to 4000 feet per minute. Duct widths from 6 inches to 12 feet can be accommodated. Ensure that the air velocity in the duct falls within these parameters. Use a velocity meter (anemometer) to check the air velocity if necessary.

Determine Mounting Location and Configuration

On ducts wider than 18 inches, it is recommended that the detector be mounted downstream of a bend, obstruction, or the supply or return air inlet.

Exception: Installation of duct detectors can be on or within commercial packaged rooftop heating and air-conditioning systems, fire/smoke dampers, and economizers. They may be mounted in either the supply and/or return air section as determined by local code.

Once a suitable location is selected, determine if the detector is to be mounted in a side-by-side "rectangular" configuration or a top-over-bottom "square" configuration (see Figure 2). For square configuration, remove the rear attachment screw, rotate the unit at the hinge, and replace the screw into the new attachment hole. Do NOT remove the hinge screw during this process. Final installation approval requires passing section 7.2.2 and/or 8.2.4 tests.

Drill the Mounting Holes

Remove the paper backing from the mounting template. Affix the template to the duct at the desired mounting location, ensuring it lies flat and smooth.

For Rectangular Side-by-Side Mounting Configuration:

Center punch at (4) target centers: (2) "A" for sampling tubes and (2) "B" for mounting tabs. Drill pilot holes at target "A" centers and cut two 1.375 inch diameter holes using a 13/8 inch hole saw or punch. Drill .156 inch diameter holes using a 5/32 inch drill at target "B" centers.

For Square Top-Over-Bottom Mounting Configuration or D4S Sensor Component Mounting:

Center punch at (4) target centers: (2) "A" for sampling tubes and (2) "C" for mounting tabs. Drill pilot holes at target "A" centers and cut two 1.375 inch diameter holes using a 13/8 inch hole saw or punch. Drill .156 inch diameter holes using a 5/32 inch drill at target "C" centers. An additional .156 inch hole can be drilled at one of the mounting tabs on the lower housing if desired.

Secure the Duct Detector to the Duct

Use two (rectangular) or three (square) of the provided sheet metal screws to secure the duct detector to the duct. CAUTION: Do not overtighten the screws.

Sampling Tube Installation

Sampling Tube Selection

The sampling tube must be purchased separately. Order the correct length, as specified in Table 1, for the duct width. It is recommended that the sampling tube length extend at least 2/3 across the duct width for optimal performance.

*Must extend a minimum of 2/3 the duct width. These sampling tubes can only be used with new InnovairFlex duct smoke detectors.

Sampling Tube Installation

The sampling tube is installed with the air inlet holes facing into the air flow. The tube's connector is marked with an arrow to assist proper installation. Ensure the arrow points into the airflow (see Figure 3). Mounting the detector housing vertically is acceptable if air flows directly into the sampling tube holes. The sampling tube and exhaust tube can be mounted in either housing connection, provided the exhaust tube is downstream from the sampling tube.

CAUTION: The sampling tube end cap is critical for proper operation. It creates the proper airflow to the sensor. Plug the end of the sampling tube with the provided end cap after any length adjustments.

A plastic exhaust tube is included. Install it into the housing connection downstream from the sampling tube connection. A longer 1-foot exhaust tube (model ETX) is available as an accessory if the molded exhaust tube does not extend at least 2 inches into the duct.

Installation Steps:

1. For tubes shorter than the duct width, slide the sampling tube (with end cap) into the housing connection that meets the airflow first. Position the tube so the arrow points into the airflow. Per NFPA, sampling tubes over 3 feet long should be supported at the end opposite the duct detector.
2. In ducts wider than 8 feet, work inside the duct to couple the other section of the sampling tube using a 1/2 inch conduit fitting. Ensure holes on both sections face into the airflow.
3. For tubes longer than the duct width, extend the tube out of the opposite side of the duct. Drill a 3/4 inch hole in the duct opposite the sampling tube hole. Angle the sampling tube downward from the detector (at least 1/4" downward per 12" of duct width) for moisture drainage (see Figure 4). Ensure 10 to 12 holes are spaced evenly across the duct width. If more than 2 holes extend outside the duct, select a shorter tube or trim the tube to leave 1 to 2 inches extending outside. Plug the end with the end cap and tape closed any protruding holes. Seal the duct where the tube protrudes.

NOTE: Air currents may cause vibration with longer sampling tubes. A 3-inch floor flange can be used to fasten the sampling tube to the duct. Drill a 1 to 11/4 inch hole for the flange.

Modifications of Sampling Tubes

If duct widths differ from specifications, a longer sampling tube can be modified. Use a 0.193 inch diameter (#10) drill to add holes, aiming for a total of 10 to 12 holes spaced evenly over the tube's length. This is a temporary fix; order the correct length tubes for permanent installation.

Remote Sampling Tube Installation

The detector can incorporate remote mounting of sampling and/or exhaust tubes. Both detector and tubes must be rigidly mounted to withstand air velocity vibrations. The detector's sampling tube location should ensure uniform airflow. The pressure differential across the sampling and exhaust ports must be between 0.01 and 1.11 inches of water, verifiable with a manometer (Section 7.1).

Measurement Tests

Air Flow

The D4120 operates in air speeds from 100 to 4000 FPM. To verify sufficient sampling, turn the air handler on and use a manometer to measure the differential pressure between the two sampling tubes. The pressure should be between 0.01 and 1.11 inches of water. For applications below 500 FPM, a current-sourcing pressure transmitter (Dwyer Series 607) or aerosol smoke testing (Section 12.5.3) may be required.

Low Flow Air Flow Test using Dwyer Series 607 Differential Pressure Transmitter

Verify air speed with an anemometer (at least 100 FPM). Wire the Dwyer transmitter as shown in Figure 5. Connect meter leads to the 1000Ω resistor. Allow 15 seconds warm-up. With both HIGH and LOW pressure ports open to ambient air, measure and record voltage drop across the resistor (measurement 1, typically 4.00 volts). Connect the HIGH side of the transmitter to the detector's sampling tube and the LOW side to the exhaust tube. Measure and record voltage drop (measurement 2). The difference between measurement 2 and measurement 1 must be greater than 0.15 volts for proper operation.

Field Wiring Installation Guidelines

All wiring must comply with the National Electrical Code and local codes. Use proper wire gauges. Color-code conductors for smoke detectors and accessory devices to prevent wiring mistakes. Improper connections can prevent proper system response during a fire.

For signal wiring (interconnected detectors or to auxiliary devices), use single conductor wire no smaller than 18 gauge. Consult control panel manufacturer specifications for allowable loop resistance.

Wiring Instructions

The D4120 and D4P120 detectors feature terminal strips with clamping plates for easy wiring. The D4S housing has 4 wiring terminals. Slide the bare wire end under the plate and tighten the screw. See Figure 7 on page 5 for system wiring.

Sensor 2 Installation/Wiring

The power board can control a second sensor (model D4S). Wire the D4S sensor to the power board using the following steps:

1. Connect wires to the four terminals in the D4S sensor housing (Tamper (Y,Y), +R, and -B). Route wires through conduit openings in the sensor and D4120 power board housings.
2. Connect the opposing ends of the wires to the "Sensor 2" terminal connections on the Power board (see Figure 6). Ensure correct terminal locations. A No. 0 or 1 Phillips screwdriver is recommended. Tamper terminals are not polarity sensitive.
3. Adjust the middle dip switch on the power board to indicate (2) sensors (see Figure 6).
4. The D4S is compatible only with new InnovairFlex models.

Unit Configuration

The D4P120 includes a three-position DIP switch for configuration:

• Sensor Switch: Determines if one or two sensors are connected to the Power Board.
• Tamper Delay Switch: Selects an instantaneous or 7-minute tamper delay. A tamper condition occurs if the sensor housing cover is removed or not secured properly.
• Trouble Shutdown Switch: Enables or disables the Aux relay switching states during a Trouble Condition.

Trouble Condition: Indicated when the Supervisory Relay switches state (Terminals 3 and 14 are open). Causes include loss of power, cover tamper timeout, wiring problems, or mismatch between connected sensors and dip switch settings.

Detector Status Indication

Detector status is indicated by LEDs on the sensor (D4S) and power board (D4P120). The power board has two LEDs, each indicating the status of one sensor. If only one sensor is connected, LED2 remains off. Refer to Table 3 for detailed status indications and relay states.

Interconnection (Multiple Fan Shut Down)

The interconnect feature allows an alarm from one device to switch the Aux Relays on other interconnected devices.

Important Interconnection Notes:

• All interconnected units must be powered using the same independent supply.
• Polarity must be maintained throughout the interconnect wiring. Connect INT+ terminals together and INT/AUX- terminals together.
• Up to 50 D4120 units may be interconnected.
• Up to 10 DH100ACDC units may be interconnected. One DH100ACDC can drive 9 DH100ACDC units or 27 D4120 units.

NOTE: Alarms can only be reset at the initiating device, not at interconnected devices.

Verification of Operation

Field Selectable Settings

Verify DIP switch settings as per Table 2 on Page 5.

Powering the Unit

Apply 24 VDC power to terminals 9 and 10 on the D4P120, or 120 VAC to the 120VAC terminals. Refer to Figure 7 and electrical specifications.

Perform Detector Check

Verify standby and trouble test per Table 3 on page 8. A remote accessory for visible indication of power and alarm is recommended. A trouble may be indicated with the cover installed if an instantaneous tamper delay is selected.

Sensitivity Verification

The sensor sensitivity is operating within its allowable range when the sensor and power board LEDs blink green every 5 seconds. A maintenance condition (sensor LEDs blink red, power board blinks amber every 5 seconds) indicates the sensor is outside factory preset sensitivity limits and requires cleaning or replacement (see Section 9). This is a valid UL test.

Detector Cleaning Procedures

Notify authorities that the system will be temporarily out of service. Disable the zone or system undergoing maintenance to prevent unwanted alarms and potential fire department dispatch.

Alarm Tests

Perform one of the following tests:

1. Test/Reset Button: Press and hold the test button on the power board cover for at least 2 seconds.
2. Magnet Test: Place the painted surface of the magnet onto the MAGNET TEST location on the sensor cover (Figure 1).
3. Remote Test Accessory: Use an approved remote test accessory.

The red alarm LED on the sensor and power board should latch on, along with any accessories. Verify system control panel alarm status and auxiliary functions (e.g., fan shutdown, damper control).

The detector must be reset by the system control panel, the front cover Test/Reset button, or a remote accessory. To reset using the power board cover button, simply press and release.

Verify airflow test per Section 7 has been performed.

Smoke Response Tests

To determine if smoke can enter the sensing chamber, visually check for obstructions. Plug the exhaust and sampling tube holes to prevent ducted air from carrying smoke away. Blow smoke (e.g., cigarette, cotton wick, punk) directly at the sensor head to cause an alarm. REMEMBER TO REMOVE THE PLUGS AFTER TESTING; otherwise, the detector will not function properly.

Smoke Entry Using Aerosol Smoke

This test is for low-flow systems (100-500 FPM). For systems over 500 FPM, use a manometer (Section 7.1).

Drill a 1/4 inch hole 3 feet upstream from the detector. With the air handler on, measure air velocity with an anemometer (at least 100 FPM). Spray aerosol smoke into the duct through the hole for five seconds. Wait two minutes for the detector to alarm. If it alarms, air is flowing through the detector. Remove the detector cover, blow out residual aerosol smoke, and reset the detector. Seal the entry hole with duct tape.

*Aerosol smoke can be purchased from Home Safeguard Industries (model 25S) or SDi (Chekkit models CHEK02, CHEK06). Refer to manufacturer's instructions.

CAUTION: Canned aerosol smoke formulas vary by manufacturer. Misuse or overuse may have long-term adverse effects. Consult manufacturer's instructions.

Install The Cover

Install covers, ensuring they fit into the base groove. Tighten the seven captured screws. Verify the sensor cover gasket is properly seated before installation.

Detector Cleaning Procedures

Notify authorities that the system will be temporarily out of service. Disable the zone or system undergoing maintenance to prevent unwanted alarms and potential fire department dispatch.

Detector Sensor

1. Remove the sensor to be cleaned from the system.
2. Remove the sensor cover by pulling outward on the four removal tabs (see Figure 10).
3. Vacuum the screen carefully. If further cleaning is needed, proceed to step 4; otherwise, skip to step 7.
4. Remove the chamber cover/screen assembly by pulling it straight out.
5. Use a vacuum cleaner or compressed air to remove dust and debris from the sensing chamber.
6. Reinstall the chamber cover/screen assembly by sliding the edge over the sensing chamber and turning until firmly in place.
7. Replace the cover, aligning with the LED holes, and gently push until it locks.
8. Reinstall the detector.

Reinstallation

1. Reinstall the detector in its housing.
2. Restore system power.
3. Perform Detector Check (Section 12.3).
4. Notify authorities that testing is complete and the smoke detector system is back in operation.

Sensor Replacement (Part No. 2D51)

1. Remove the sensor head by rotating counterclockwise.
2. Pull gently to remove it.
3. To replace, align the mounting features and rotate the new sensor head clockwise into place.

Optional Accessories

RTS451/RTS451KEY Remote Test Station

The RTS451/RTS451KEY facilitates testing of the duct smoke detector's alarm capability and allows resetting the detector. Connect as shown in Figure 12. Wire runs must be limited to 25 ohms or less per interconnecting wire. If a system control panel is used, the panel itself may require testing.

SSK451 Multi-Signaling Accessory

The SSK451 combines a sounder with key-activated test and reset functions. Green, amber, and red LEDs indicate power, trouble, and alarm status. An optional strobe (PS24LOW) with a smoke lens can be added.

Connect the SSK451 as shown in Figure 14.

Wiring Diagrams for Optional Accessories

Figures 11, 12, 13, and 14 provide wiring diagrams for various optional accessories, including MHR/MHW, RA400Z, APA151/APA451, RTS451/RTS451KEY, and SSK451. These diagrams illustrate connections between the D4120 duct detector and the accessories, often showing configurations without a control panel.

System Wiring Diagram for 4-Wire Duct Smoke Detectors

Figure 7 illustrates the system wiring for 4-wire duct smoke detectors, detailing power inputs (24VAC/DC or 120VAC), auxiliary contacts for fan shutdown, supervisory contacts, and alarm initiation loop connections to a control panel. It emphasizes breaking wire runs for system supervision.

Three-Year Limited Warranty

System Sensor warrants its product to be free from defects in materials and workmanship under normal use and service for a period of three years from the date of manufacture. The warranty obligation is limited to the replacement of defective parts. For warranty service, contact System Sensor at 1-800-SENSOR2 for a Return Authorization number and instructions for returning the unit.