Dwyer CDX User Manual

Series CDX Wall Mount Carbon Dioxide Transmitter

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Specifications - Installation and Operating Instructions

Bulletin AQ-CDX

The Series CDX Carbon Dioxide Transmitter is a low cost and high

performing CO2 sensor. On-Demand ventilation using CO2 sensors
prevents energy losses from over ventilation while maintaining indoor air
quality. The potential for the greatest energy saving occurs in areas
where occupancy varies over the duration of the day. The Series CDX
Transmitters utilize a proprietary logic algorithm to eliminate the need for
manual calibration in applications where the indoor CO2 level drops to
outside levels during unoccupied periods.

MOUNTING

Push the tabs on the bottom of the housing to remove the cover. Mount
the back plate to the wall or junction box with the supplied screws and
make the necessary wire connections. Attach the cover to the back plate
by aligning the top clips and securing the bottom clips.

SELECTION OF VOLTAGE OUTPUT

Prior to wiring, verify that the voltage selection jumper is set to the
desired output type. For voltage output selection, the output can be 0 to
5 VDC or 0 to 10 VDC. Voltage (see below).

0 to 10 V Jumper Selected (left), 0 to 5 V Jumper Selected (right).

SPECIFICATIONS
Range: 0 to 2000 PPM.
Accuracy: ±30 PPM or 3% of reading, whichever is higher. CO2

accuracy statement excludes standard gas used for calibration that has
an accuracy of 2% and there is a potential digital to analog error of up
to 1%.

Temperature Dependence: 0.2% FS per °C (± 0.11% per °F).
Stability: < 2% of FS over life of sensor (15 years).
Pressure Dependence: .135% of reading per mm of Hg.
Response Time: 5 s.
Warm Up Time: < 2 min (operational), 10 min (max. accuracy).
Temperature Limits:

Operating: 32 to 122°F (0 to 50°C);
Storage: -40 to 158°F (-40 to 70°C).

Humidity Limits: 0 to 95% relative humidity, non-condensing.
Power Requirements: 18 to 30 VAC RMS, 50/60 Hz, or 18 to 42

VDC, polarity protected.

Power Consumption: .7 W @ nominal voltage of 24 VAC RMS.
Sensor: Non-dispersive infrared (NDIR) absorption.
Output: Analog, 0 to 5 V or 0 to 10 V jumper selectable (100 Ω output

impedance), 4 to 20 mA (RL maximum 500 Ω).

Housing: Flammability classification UL94 5VA.
Weight: European Housing: 5.44 oz (154 g); North American Housing:

6.24 oz (177 g).

Agency Approvals: CE, RoHS.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: [phone] e-mail: [e-mail]

Phone: [phone] www.dwyer-inst.com

WIRING CONFIGURATIONS

Figure 1: Current Wiring for 3-Wire System – AC Power

CAUTION

evice. Wiring the units as 2-wire or loop-powered devices will irreparably damage

d
the sensors and void the warranty.

he Series CDX is either a 3-wire or 4-wire type configuration,

T

owered by either AC or DC voltage. It is not a 2-wire or loop

p

POWER SUPPLY REQUIREMENTS

The sensor can be powered with either 18 to 30 VAC or 18 to 42 VDC,
while the DC power is polarity protected. AC power must be at a frequency
between 50 to 60 Hz.

Recommended length of wire after being
stripped of insulation for terminal pin (left).

CALIBRATION

The Series CDX is factory set with the proprietary logic function activated.
The logic function allows the sensor to continuously re-calibrate itself when
the indoor concentrations drop to levels similar to outside conditions when
the building is unoccupied. The building must be unoccupied for a
minimum of 4 hours or more for this self calibration to be effective. The
logic allows the sensor to maintain its calibration over the life of the sensor.

Figure 2: Voltage Wiring for 3-Wire System – AC Power

Figure 3: Current Wiring for 4-Wire System – AC Power

Figure 4: Voltage Wiring for 4-Wire System – AC Power

WARNING

shock can cause personal injury. Please read and follow the wiring instructions
precisely because improper wiring my cause permanent damage to the product.

Before performing service or maintenance operations on the
systems, turn OFF main power switches to the unit. Electric

The Series CDX has two terminal pins that are connected inside the sensor
to a common/ground: pin #7 on the I/O terminal blocks and pin #2 on the
power block. Do NOT connect positive 24 VAC power line to pin #2 of the
terminal block.

ACCESSORY ENCLOSURES

When mounting these products inside the ductwork, seal the hole around
the wires and leave the duct insulation in place to prevent condensation
which may damage the sensor.

Model 1508 Duct Mount Enclosure

The CDX units can be installed inside a Model 1508 Duct Mount Enclosure.

Model 1552 Outside Air Measurement Enclosure

This NEMA-3R weatherproof enclosure includes thermostat and allows
installation of the sensor in environments with temperatures down to -40°F
(-40°C).

Duct Mount Enclosure (left), Outside Air Enclosure (right)

MAINTENANCE/REPAIR

Upon final installation of the Series CDX, no routine maintenance is
required. The Series CDX is not field serviceable and should be returned if
repair is needed. Field repair should not be attempted and may void
warranty.

WARRANTY/RETURN

Refer to “Terms and Conditions of Sale” in our catalog and on our website.
Contact customer service to receive a Return Goods Authorization number
before shipping the product back for repair. Be sure to include a brief
description of the problem plus any additional application notes.

©Copyright 2013 Dwyer Instruments, Inc. Printed in U.S.A. 11/13 FR# R6-444152-00 Rev. 1

DWYER INSTRUMENTS, INC.

Phone: [phone] www.dwyer-inst.com

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: [phone] e-mail: [e-mail]