Series CDTR Carbon Dioxide/RH/Temperature Transmitter

Brand: Dwyer Instruments, LLC

The Series CDTR Carbon Dioxide, Relative Humidity and Temperature Transmitters reduce the number of sensors mounted on a wall or in a duct.

By combining CO2, RH, and temperature in one device, system integrators are able to reduce installation time while lowering material cost at the same time. 

Like our popular Series CDT Carbon Dioxide Transmitter, a single beam dual wavelength non-dispersive infrared (NDIR) sensor is used to automatically correct the measurement in both occupied and unoccupied buildings against light source aging effects.

In order to achieve the best possible accuracy, the Series CDTR also includes digital barometric pressure adjustment and the ability to field calibrate the sensor.

Universal outputs for both carbon dioxide and relative humidity allow users to select the transmitter output to be 4 to 20 mA, 0 to 5 VDC, or 0 to 10 VDC to work with virtually any building management controller. 

Additionally, passive thermistor or RTD sensor can be ordered for a temperature output. For applications that require visual indication, the wall mount configurations of the Series CDTR can be ordered with an integral LCD display.

The display can be configured to display temperature only, relative humidity only, CO2 only, CO2 and humidity, or CO2 and temperature.

Push buttons are standard on all configurations of the transmitters for access to the menu structure. To prevent tampering, the action of the buttons can be locked out using an internal jumper selection.
  • Digital Intelligence Temperature Compensation Algorithm (DITCA™) eliminates error due to the self heating effects of wall mount combination devices
  • Single Beam Dual Wavelength NDIR CO2 Sensor
  • Replaceable Humidity/Temperature Sensors
  • Physical Hardware Lockout
  • Service display tool available for duct mount and wall mount units without an LCD
  • Relay Output Option



  • ± 2 % - RH
  • ± 40 ppm ± 3 % of Reading (CO₂)


  • Demand Control Ventilation in Schools, Office Buildings, Hospitals, & Other Indoor Environments

Approvals & Certifications

  • FC Factory Calibration Certificate
  • LEED

Approvals & Certifications

  • CE


  • 2 W - Average
  • 3.75 W - Peak


  • LCD Display

Flow Rate

  • 0 to 2000 ppm
  • 0 to 5000 ppm


  • 10 to 95 % Relative Humidity, Non-Condensing


  • Duct Mount
  • Wall Mounted


  • 0-10 Vdc - Voltage
  • 0-5 Vdc - Voltage
  • 4-20 mA - Current
  • SPST Normally Open, 2 A at 30 Vdc

Output Format

  • Relay Output

Power Requirement

  • 16-35 Vdc
  • 19-28 Vac

Response Time

  • 2 minutes for 99 % Step Change

Sensor / Probe Type

  • NTC Thermistor (10 kiloohms Typical Ll & Lll, 3 kiloohms, 20 kiloohms)
  • RTD - Pt100 & PT1,000 ohms

Temperature Range

  • 0° to 50° C (32° to 120° F)

  • Demand control ventilation in schools, office buildings, hospitals, and other indoor environments
  • LEED® certification

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