Series-CDTV

Supported Applications

The Dwyer Series CDTV is a Carbon Dioxide (CO2) and Volatile Organic Compound (VOC) transmitter designed for HVAC systems to optimize airflow based on space occupancy. By detecting both CO2 levels and VOCs, the series supports demand-controlled ventilation strategies that reduce energy costs by lowering conditioned air intake during lower occupancy periods. The dual-sensor capability allows detection of fumes requiring exhaust even when occupancy is low.

Applications include indoor environments where monitoring combined gas concentrations reduces labor and material costs compared to installing separate CO2 and VOC transmitters. The series supports duct mount configurations for direct airflow measurement and wall-mount housings for room-level sensing.

Operating Conditions & Performance

The Series CDTV operates within an ambient temperature range of 32 to 122°F (0 to 50°C). Measurement ranges are available as CO2: 0 to 2000 ppm or 0 to 5000 ppm depending on the model, and VOC: 0 to 2000 ppm CO2 equivalent. Accuracy for CO2 is specified as ±40 ppm +3% of reading.

Performance characteristics include a response time of 2 minutes for 99% step change (CO2) and 5 minutes (VOC). The sensor technology utilizes Single-beam, dual-wavelength Non-Dispersive Infrared (NDIR) for CO2 measurement and MEMS metal oxide semiconductor for VOC detection. Temperature dependence is ±8 ppm / °C at 1100 ppm, with a pressure dependence of 0.13% of reading per mm of Hg.

Power requirements are 16 to 35 VDC or 19 to 28 VAC. Power consumption averages 2 watts with a peak of 3.75 watts. A warm-up period of 30 minutes is required upon powering the transmitter for it to adjust to current CO2 concentration.

Configuration Options

The series offers configurable output signals, housing styles, and optional features tailored to specific installation needs:

• Housing Configurations: Duct mount (NEMA 4X / IP66 for housing only) or North American style wall mount (IP20).
• Output Signals: Current outputs include 0 to 20 mA, 4 to 20 mA, 0 to 10 mA, or 2 to 10 mA (max load resistance 500 Ω). Voltage outputs include 0 to 10 VDC, 2 to 10 VDC, 0 to 5 VDC, or 1 to 5 VDC (min load resistance 500 Ω).
• Relay Output: Optional SPST NO relay rated at 2A @ 30 VDC.
• Sensor Elements: CO2 ranges of 0-2,000 ppm or 0-5,000 ppm; VOC range fixed at 0 to 2,000 ppm CO2 equivalent. Temperature sensor options include None (code 0), 10 KΩ NTC thermistor type III (A), 10 KΩ NTC thermistor type II (B), 3 KΩ NTC thermistor (C), Pt100 Ω RTD (D), Pt1000 Ω RTD (E), or 20 KΩ NTC thermistor (F).
• Display & Accessories: Optional LCD display available for wall mount models only. Remote Display Model A-449 is supported via mini USB plug connection.
• Certifications & Options: CE approved. Factory calibration certificate and Certificate of Calibration are available options.

Key Product Differences

The Series CDTV distinguishes between two primary mounting styles: Duct mount (code 'D') for direct integration into air handling systems, and North American style wall mount (code 'N'). The duct mount version features a cylindrical housing with an overall length of 11-49/64" [298.85] mm and diameter Ø3-5/16" [84.14], while the wall mount unit measures 4.50 in height, 2.80 in width, and 1.10 in depth.

Model numbers follow a structured format indicating gas concentration range (e.g., '-2' for 0 to 2,000 ppm CO2; '-5' for 0 to 5,000 ppm), housing configuration ('D' or 'N'), and output selections. Wall mount variants may include an LCD display option (-LCD) not available on duct models.

Configuration parameters such as relay set points (RON/ROF), CO2/VOC low/high output ranges (COL/COH, VOL/VOH), barometric pressure compensation (BAR), and average atmospheric CO2 values (AAC) are adjustable via the device menu. The transmitter is not field serviceable; repairs require return to the manufacturer.