Honeywell C7355B In-Duct IAQ Monitor

Supported Documents

• IAQ Monitor Submittal Data, 31-00439
• IAQ Monitor User Guide, 31-00438
• IAQ Monitor Quick Start Guide, 31-00441

Introduction

The Honeywell C7355B In-Duct IAQ Monitor is designed for installation in outdoor or return air ducts. It monitors key indoor air quality parameters including PM2.5, PM10, CO2, TVOC, Temperature, and Relative Humidity. The device communicates via RS-485 and integrates with building automation systems. Please read these instructions carefully before installing and using the device.

When Installing This Product

1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
2. Verify that the product's ratings match your application requirements.
3. Installation should only be performed by a trained and experienced service technician.
4. After installation, check the product's operation.
5. Ensure all wiring complies with applicable codes, ordinances, and regulations.

WARNING: Electrical Shock Hazard

Can cause severe injury, death, or property damage. Disconnect the power supply before beginning installation to prevent electrical shock and equipment damage. More than one power supply may need to be disconnected.

Installation Requirements (IMPORTANT!)

• For supply air applications: Install the device on the main air duct, away from the supply air fan and branch ducts.
• For return air applications: Install the device on the main air duct close to the return air fan, or more than 1 meter from the return air outlet.
• Pitot Tube Installation: Install the pitot tube in accordance with the direction of the air flow.
• The device should be installed in an accessible location for convenient maintenance.
• The power supply is 24VAC/VDC. Ensure the power connection is waterproof and safe.
• The pitot tube and monitor are calibrated as a pair. Ensure their serial numbers match.
• When removing or installing the pitot tube, the monitor must be powered off and disconnected from electricity. The pitot tube must be fitted and tightened securely to avoid issues with the temperature and humidity sensor.

IMPORTANT: Electrical Interference

To prevent erratic sensor readings caused by electrical interference, keep wiring runs as short as possible. Do not run unit wires adjacent to line voltage electrical distribution systems. Use shielded cable and ground the cable shield only at the controlled equipment case.

WEEE (Waste of Electrical and Electronic Equipment)

This symbol ♻️ (crossed-out wheelie bin) indicates that the product must be disposed of separately from household waste at the end of its life. Please dispose of packaging and the product at an appropriate recycling center. Do not burn the device or dispose of it with regular domestic refuse. Follow applicable laws for proper disposal.

Check Accessories

Unpack the box and verify the contents against the following list:

• Instruction manual – 1 piece
• In-Duct IAQ monitor – 1 unit
• Pitot tube for monitor – 1 piece
• Waterproof connector – 1 piece
• Pipeline seal ring – 1 piece
• Assembly screws – 2 pcs; duct mounting screws – 2 pcs
• Hexagonal screwdriver – 1 piece
• Filter – 1 piece

Monitor Overview

The IAQ monitor enclosure includes a pitot tube, a main unit sensor compartment, a main unit communication control compartment, and external temperature & humidity sensors. The main unit sensor compartment is designed to ensure air tightness for accurate measurements.

INSTALLATION

Assembly of Main Unit and Pitot Tube

1. Refer to the markings on the main unit (as shown in Figure 2). Turn counterclockwise to remove and clockwise to attach. The pitot tube must be matched with its original main unit, indicated by the same serial number.
2. The pitot tube is paired with the main unit; their serial numbers are identical. Do not mix pitot tubes with other sensor main units.
3. Install the pitot tube with the side marked 'Windward Side' facing down, aligning it with the rear mounting hole of the main unit.
4. After inserting the pitot tube into the main unit assembly hole, ensuring alignment marks match, rotate the pitot tube 90 degrees clockwise to secure it.

Installation for Airflow from Right to Left (Factory Default)

1. Determine the installation position and cut a 1-3/8 inch (35 mm) diameter hole in the air duct. Insert the pitot tube into the duct. Note: The side of the pitot tube marked 'Windward Side' should face the airflow direction.
2. Secure the pitot tube to the outside of the air duct using a tapping screw.
3. Install the main unit, connecting it horizontally to the pitot tube interface as shown in Figure 8.
4. Rotate the unit 90 degrees clockwise to complete the installation (see Figure 9).

Installation for Airflow from Left to Right

If the airflow direction is opposite (from left to right), the monitor's face may need to be installed in an upside-down orientation. If the monitor requires a positive orientation, reverse the built-in sensor module before installing it on the air duct. This reversal is recommended only if absolutely necessary for daily operation.

1. Unscrew the four assembly screws and open the upper casing part of the main unit (see Figure 10).
2. Pull out the air inlet filter from the lower right side of the sensor module. Remove the fixing screws from the middle of the module (see Figure 11).
3. Remove the sensor module from its housing with the cable. Rotate the module 180 degrees (see top image in Figure 12) and install it back into the original position (see bottom image in Figure 12). Note: When reinstalling the sensor module in its original position, ensure the cable passes under the compartment as shown in Figure 13. Passing the cable over the compartment will prevent the sensor module from being fixed correctly.
4. Fix the sensor module and insert the air inlet filter into the upper left slot of the module (see Figure 14).
5. Replace the sensor compartment cover and secure it with the original screws (see Figure 15).
6. Install the pitot tube. Confirm the installation position and cut a 1-3/8 inch (35 mm) diameter hole in the air duct. Note: The side of the pitot tube marked 'Windward Side' should face the airflow direction.
7. Insert the pitot tube and fix it with screws (see Figure 17).

POWER SUPPLY AND RS-485 WIRING

IMPORTANT: All wiring must comply with local electrical codes and ordinances. Follow equipment manufacturer wiring instructions. Power must not be connected while wiring. Incorrect wiring can result in electrical shock and/or equipment damage.

1. Remove the cover of the electrical wiring compartment on the main unit (see Figure 21).
2. Remove the two terminal blocks for power supply and RS-485 respectively (see Figure 22).
3. Run the power cable and RS-485 cable through each waterproof connector (see Figure 23).
4. Connect the cables to the terminal blocks:
   • Power Supply: Connect to the left terminal block (typically labeled 12-28VDC/18-27VAC).
   • RS-485: Connect to the right terminal block (typically labeled RS485, with terminals G+, G0, B, A) (see Figure 24).
5. Plug the terminal blocks back onto the pin connectors and tighten the waterproof connectors (see Figure 25).
6. Replace the cover of the electrical wiring compartment and tighten the screws (see Figure 26).

Dimensions and Mounting Holes

The following dimensions are provided in inches (mm):

• Overall Height: 8.39 in. (213 mm)
• Overall Width: 4.92 in. (125 mm)
• Overall Depth (Main Unit): 7.09 in. (180 mm)
• Pitot Tube Length: 13.58 in. (345 mm)
• Pitot Tube Insertion Depth: 9.25 in. (235 mm)
• Duct Hole Diameter for Pitot Tube: 1.38 in. (35 mm)
• Mounting Hole Spacing (Vertical): 7.09 in. (180 mm)
• Mounting Hole Spacing (Horizontal): 4.92 in. (125 mm)
• Sensor Compartment Depth: 2.58 in. (65.5 mm)
• Pitot Tube Diameter: 1.19 in. (30.4 mm)
• Main Unit Width: 4.92 in. (125 mm)
• Main Unit Height: 8.39 in. (213 mm)
• Main Unit Depth: 2.58 in. (65.5 mm)
• Pitot Tube Mounting Flange Diameter: 3.74 in. (95 mm)
• Pitot Tube Collar Diameter: 3.05 in. (77.5 mm)
• Pitot Tube Mounting Screw Hole Diameter: 0.18 in. (4.5 mm)

Contact Information

Honeywell Building Technologies
Honeywell
715 Peachtree Street NE
Atlanta, GA 30308
customer.honeywell.com

Honeywell Building Technologies
Honeywell GmbH
Böblinger Strasse 17
71101 Schönaich, Germany
buildings.honeywell.com

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