VOC, Temp & RH Transmitter Duct (VOCTD) 24V

VOC, Temp & RH Transmitter Duct (VOCTD) 24V

The Flamefast Duct Mounted VOC (Volatile Organic Compounds), Temperature and Relative Humidity transmitter offers an accurate and cost effective solution for the HVAC market, with 0-10V outputs for VOC, Temp and RH Levels (outputs depend on model selection). The VOCs are measured and displayed in CO2 equivalent for easy interpretation.

With a robust and easy to install flange mounted enclosure, the unit can be mounted in rugged environments with confidence and the hinged front makes installation quick and easy.

Using the built in Volt Free Contact, the unit can be easily interfaced with Ventilation and Window Control systems.

The unit offers two user selectable programmes with different relay set points depending on the application. Custom software profiles are also available to control the relay set point and the traffic light changeover levels, based on any combination of VOCs, Temp & RH (VOC as default).


View FileVOC, Temp & RH Transmitter - Duct (CO2TD) 24V

Key Features

  • 24V AC/DC Power Supply
  • Low power consumption
  • Robust, hinged enclosure
  • Optional digital readout
  • Optional traffic light indication
  • 3x 0-10V outputs (full-scale linear)
  • Volt free contact output
  • Typical 10 year life expectancy
  • Self-calibrating VOC sensors
  • 200mm duct probe length

Technical Specification

Power Supply 24V AC/DC ±10%
Power Consumption 50mA Max
VOC Range (CO2 Equivalent) 400-2,000ppm
VOC Accuracy ±5% @ NTP
VOC Display Resolution 1ppm
VOC Sensor Type Semiconductor
Temp Range (0-10V) 0 - 50°C
Temp Accuracy ±0.3°C @ 20 - 40°C
Temp Display Resolution 0.1°C
RH Range (0-10V) 0 - 100%
RH Accuracy +/-2% @ 20 - 80%
RH Display Resolution 0.1%
VFC Output Rating SPST - 100mA @ 24V Max
Operating Conditions Temp 0°C to 50°C
Humidity 0 to 95% (NC)
Sampling Method Diffusion
Warm-up Time 30 Seconds
IP Rating IP66 (External to duct)
Housing Material Flame Retardant ABS/PC
Approval CE


Height 152 mm
Width 110mm
Depth 50 mm
Probe Length 200 mm

Installer Selectable Options

  • Backlight (Enable/Disable)
  • Volt Free Contact set point
  • Display Options:
    • On standard Model - replace PPM reading with 'CO2'
    • On -H model - remove RH readout

The VOCTD has four factory set user selectable programmes to control the Volt Free Contact. These are as follows:

Program 1 2
Green - Yellow 1,000 1,000
Yellow - Red 1,500 1,500
Relay Position N/O N/O
Relay Set Point 1,000 1,500
CO2 Range 2,000 2,000

Custom programs available on request

Part Numbers & Options / Accessories

Part No Description
VOCTD Duct Mount VOCTransmitter
VOCTD-H Duct Mount VOC, Temp & RH Transmitter
-L Adds a Traffic Light LCD to any of the above

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