D341 BOSCH

D341 FOUR-WIRE DUCT SMOKE DETECTOR HOUSING.

The D341 Four‑wire duct smoke detector housings mount on the ducts of heating, ventilation, and air conditioning (HVAC) systems. The D285DH detector in the housing monitors the presence of smoke in the conditioned air. The housing works with all 24 VDC or VAC or 120 VAC, UL Listed four‑wire control panels. The efficient housing design samples the air passing through a duct and detects potentially hazardous conditions. When smoke is detected, the detector sends an alarm signal to the control panel or HVAC control equipment. The control panel or HVAC control equipment initiates the necessary action to control air handling systems.

D341 Alarm/Trouble Indication

A D344‑RT, a D344‑RL, or a DRA‑5 can provide remote LED indication of alarm and trouble status. The red LED lights for an alarm. An open loop causes the yellow Trouble LED to flash.

• For 1 ft. (30.5 cm) to 10 ft. (3 m) ducts with air velocity between 300 ft./min. to 4000 ft./min. (1.52 m/s to 20.3 m/s)
• Easy duct tube installation through the housing cuts installation time
• Detector test and reset without removing covers
• Clear cover allows quick visual inspection
• Tube filters, dust immune smoke detector, and easy disassembly for cleaning reduce maintenance time and cost

Air Sampling

Use the duct detector housings in air ducts between 1 ft. (30.5 cm) and 10 ft. (3.05 m) wide. Air velocities must be between 300 ft./min. and 4000 ft./min. (1.52 m/s to 20.3 m/s). Air is forced into the detector through a sampling tube and returned to the duct through an exhaust tube. Sampling tubes should extend across the width of the duct. Bosch Security Systems, Inc. offers sampling tubes in three different sizes. Combine or cut the tubes to make other lengths. Sampling tubes over 3 ft. (91.4 cm) must be supported at the end opposite the duct detector. Sampling tubes are provided with an end plug that must be installed in the open end.

D341 System Testing 

Test the system by:

• Placing an external magnet on the detector housing, or
• Switching a signal from a remote test station (requires an external 24 V supply) Reset the system by power shutdown or, if a D344‑RT is connected, use the key-operated switch.

Compatible Panels

The D341 Four‑wire duct smoke housings are compatible with all 24 VDC or VAC, or 120 VAC UL Listed control panels.

Remote Indicators

NFPA 72 requires detectors have remote alarm indicators where duct smoke detectors are installed: • in concealed locations • is more than 10 ft. (3 m) above the floor • where the detector’s alarm indicator is not visible to responding personnel The optional D344‑RT Remote test/indicator plate, D344‑RL Remote indicator plate, or DRA‑5 Remote indicator plate can satisfy this requirement.

D341 Power Considerations

The detector housing provides one primary power source of 24 VDC, 24 VAC, or 120 VAC. Do not connect a high-voltage AC source and a low‑voltage AC/DC source to the same housing.

D341 Duct detector housing, 4-wire 24/120V

Four-wire duct detector housing that works with all 24 VAC/VDC or 120 VAC UL Listed four‑wire control panels.