Honeywell C7232A,B Sensor and Controller

Application

The C7232 Sensor and Controller is a stand-alone carbon dioxide (CO2) sensor designed for use in determining ventilation necessity with HVAC controllers. It measures the CO2 concentration in ventilated spaces or ducts and is utilized in ventilation and air conditioning systems to regulate the amount of fresh outdoor air supplied, thereby maintaining acceptable CO2 levels within a space.

Features

• Models available with an LCD that provides sensor readings and status information.
• Utilizes Non-Dispersion-Infrared (NDIR) technology for measuring carbon dioxide gas.
• Features a gold-plated sensor for long-term calibration stability.
• Provides voltage output based on CO2 levels.
• Models include an SPST relay output.
• Designed for CO2-based ventilation control.
• Incorporates an Automatic Background Calibration (ABC) algorithm, which reduces the need for typical zero-drift check maintenance through long-term evaluation.

Specifications

Models: C7232 Sensor and Controller. A stand-alone carbon dioxide (CO2) sensor with two jumper-adjustable outputs (one analog and one SPST relay).

C7232A: Wall mount model.

C7232B: Duct mount model.

Note: Models are available with or without a 4-digit LCD indicating the current CO2 concentration.

Dimensions

C7232A: See Figure 1. Figure 1 illustrates the dimensions for the C7232A wall mount model, showing its compatibility with a standard single-gang junction box and providing key measurements: 3-5/32" (80mm) H, 2-3/8" (60mm) W, 1" (25mm) D.

C7232B: See Figure 2. Figure 2 shows C7232B duct mount dimensions, including a sampling tube, with key measurements: 5-5/8" (142mm) H, 1-5/8" (41mm) W, 8" (203mm) L (incl. tube).

Sensor Performance Ratings

Response Time: 2 minutes.

Carbon Dioxide Sensor

Operation: Non-dispersive infrared (NDIR).

Sampling: Diffusion.

Range: 0 to 3000 ppm ±5% and ±50 ppm.

Annual Drift: 20 ppm (nominal).

Calibration Interval: Five years.

Electrical Ratings

Power Supply: 24 Vac ±20%, 50/60 Hz (Class 2).

Maximum Power Consumption: 3W.

Peak Current (at 20 ms): 600 mA.

Relay

Configuration: Shipped Normally Open (N.O.), configurable with software.

Contact Rating: 1A at 50 Vac/24 Vdc.

Minimum Permissible Load: 1 mA at 5 Vdc.

Linear Analog Output

Voltage: 0/2-10 Vdc (resistive load greater than 5000 ohms).

Current: 0/4-20 mA (resistive load less than 500 ohms).

Outputs (Jumper Adjustable)

Analog: 0-10 Vdc (Default: 2-10 Vdc, 500 to 1500 ppm).

Relay: Normally Open SPST (Default: Close at 1000 ppm).

Ambient Ratings

Temperature:

Operating: +32°F to +122°F (0°C to +50°C).

Storage: -4°F to +158°F (-20°C to +70°C).

Relative Humidity (non-condensing): 0 to 95 percent.

CO2 Pressure Dependence: 1.4% change in reading per 1 kPa deviation from 100 kPa.

Connections

Wiring:

C7232A: 20-gauge cable with six 8-inch leadwires.

C7232B: 20-gauge cable with six 6-inch leadwires.

Mounting

C7232A: Vertical surface mounting with a standard single-gang junction box.

C7232B: Sheet metal duct mounting with a sampling tube.

Automatic Background Calibration (ABC) default: On.

Approvals

Underwriters Laboratories Inc. Component Recognition: UL94-5V, File No. E191465.

CE Marking.

C7232A: NEMA1 rated.

C7232B: NEMA3 rated.

Accessories

32002181-001: Zero Calibration and Service Kit.

CO2 Range Jumper Settings

Note: Relay switching points are set by jumpers. When the level reaches this value, the contacts close; when the level drops 100 ppm below this value, the contacts open.

Output Signal Jumper Settings

Note: Jumpers AN1 and AN2 should be set identically. The factory default setting is ON for both. The high and low values of the CO2 range are not affected by the output signal range.

C7232 Wiring Connections

Figure 6 is a wiring diagram for the C7232, detailing power connections (Red for 24 Vac Hot, Black for 24 Vac Common) and output signal connections (Yellow for Analog OUT1, Brown for Analog Common, Orange for Normally Open Relay, Green for Relay Common). It includes a note regarding the requirement for disconnect means and overload protection.

Ordering Information

To purchase replacement and modernization products, refer to the TRADELINE® Catalog or price sheets from your TRADELINE® wholesaler or distributor for the complete ordering number.

For additional questions, further information, or comments on products or services, please write or phone:

1. Your local Home and Building Control Sales Office (refer to your phone directory).
2. Home and Building Control Customer Logistics, Honeywell Inc., 1885 Douglas Drive North, Minneapolis, Minnesota 55422-4386. Phone: (612) 951-1000.
3. In Canada: Honeywell Limited/Honeywell Limitée, 155 Gordon Baker Road, North York, Ontario M2H 3N7.

International Sales and Service Offices are located in all principal cities worldwide. Manufacturing facilities are located in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, and U.S.A.

Installation

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 ratings provided in the instructions and on the product are suitable for your application.
3. The installer must be a trained and experienced service technician.
4. After installation, perform a product checkout as detailed in these instructions.

IMPORTANT: All wiring must comply with applicable codes, ordinances, and regulations.

CAUTION: Health Hazard

Improper use can create dangerous situations. This device is intended for sensing carbon dioxide only. For life-safety applications, it should function only as a secondary or lesser device.

CAUTION: Electrical Shock or Equipment Damage Hazard

Can shock individuals or short equipment circuitry. Disconnect power supply before installation.

CAUTION: Equipment Damage Hazard

Electrostatic discharge can short equipment circuitry. Ensure you are properly grounded before handling the unit.

C7232A Cover Removal/Replacement

C7232A Cover Removal (See Figure 3)

1. Remove the button head socket cap screw and set it aside.
2. Insert the head of a small screwdriver into the slot located at the center and near the top of the cover.
3. Gently pull the handle down towards the bottom of the device until a small gap appears between the subbase and the cover.
4. Remove the screwdriver and pull the cover straight down until it reaches a stop.
5. Pull the cover straight off the subbase.

C7232A Cover Replacement

1. Feed the wires through the opening in the subbase.
2. Place the cover, with a small gap at the top, flat on top of the subbase.
3. When the cover rests flat on the subbase, slide it straight up until it latches in place.

Location and Mounting

C7232 Sensors can be mounted directly on a wall, sheet metal duct, or a panel. When planning the installation, ensure sufficient clearance for maintenance and service. Mount the sensor in a well-ventilated area.

NOTES: Do not install the sensor where it may be affected by:

• Drafts or dead spots behind doors and in corners.
• Air from ducts.

Wall Mounting

The C7232 Wall Mount models can be attached using two or four screws:

1. Remove the C7232 cover.
2. Mount the subbase to the wall using washers and two or four screws (not supplied), appropriate for the wall material.
3. NOTE: For mounting on a junction box, refer to Figure 4. Figure 4 depicts C7232A junction box mounting, showing the subbase attached to a conduit box.
4. Replace the cover.

Duct Mounting (See Figure 5)

1. Place the gasket on the aspiration tube.

2. IMPORTANT: Ensure the largest tab at the tube control end is positioned at the top.

3. Insert the tube into the duct and attach using screws and washers.

4. IMPORTANT: Leakage into the duct or the C7232 box cover from the room can skew sensor readings. Ensure the box cover and duct seal completely.

5. Place the o-ring on the tube end and mount the control to the tube. Figure 5 illustrates C7232B duct mounting, showing aspiration tube insertion and control unit attachment.

Wiring

The device is shipped with default output settings as shown in Tables 1 and 2. Set the jumpers and wire the device according to Table 3 and Figure 6.

CAUTION: Electrical Shock or Equipment Damage Hazard

Can shock individuals or short equipment circuitry. Disconnect power supply before installation.

CAUTION: Equipment Damage Hazard

Electrostatic discharge can short equipment circuitry. Ensure you are properly grounded before handling the unit.

IMPORTANT:

• All low voltage connections to this device must be 24 Vac Class 2.
• All wiring must comply with applicable local codes, ordinances, and regulations.

Calibration

To calibrate the sensor:

1. Using the 32002181-001 Calibration Kit, eliminate the CO2 gas.

2. IMPORTANT: Any CO2 present during calibration will skew the sensor zero level, resulting in incorrect CO2 level reports.

3. Once the sensor stabilizes, use a screwdriver to connect the two MENU soldering pads.
4. The display should indicate "CAL".
5. Execute the zero calibration by connecting the two ENTER soldering pads.
6. The display should return to showing the measured CO2 level.

Checkout

Perform a quick test of the unit while powered:

1. Stand close to the unit and breathe air into the sensor.
2. Check the CO2 level registered by the controller to ensure a significant rise.
3. When connected to a damper in a ventilation system, the controller typically signals an increase in air flow.