Category
CO2 Transmitters: Room, Duct or Outdoor
Room, duct or outdoor? Compare CO2 transmitters and choose the right one for your application.
A CO2 transmitter measures carbon dioxide in a room, duct or outdoor air so a BMS can adjust ventilation to match occupancy. Produal's range covers room, duct and outdoor models, with standard ranges and high-range 10,000 ppm versions for spaces that run higher than a typical office.
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6 Products · CO2 Transmitter
Selection guide
CO2 Transmitters: Room, Duct or Outdoor Guide
How a CO2 transmitter works
Most models use non-dispersive infrared (NDIR) sensing: CO2 absorbs infrared light at a specific wavelength, and the transmitter measures how much light gets through a sample chamber to calculate the concentration. NDIR sensors are stable over time and don't consume the gas they measure, which keeps recalibration intervals long compared with older electrochemical designs. All the Produal models here also measure temperature, so one device gives both readings from a single installation point.
Room, duct or outdoor?
- Room transmitters: the RT-CO2 and RTX-CO2 measure where people actually are. Choose these for offices, meeting rooms and classrooms that need their own control.
- Duct transmitters: the HDK measures return or extract air from an air handling unit, giving one average reading for the zone it serves rather than a room-by-room value.
- High range: the HDK 10K and HDU 10K measure up to 10,000 ppm, for unheated spaces or processes where CO2 runs well above office levels.
- Display: the RTX-CO2-D adds a touchscreen showing live readings to occupants, useful where people should see the air quality directly.
- Output and control: check what your BMS or controller accepts, and note that the RTX-CO2 has a built-in P/PI controller for standalone use without a full BMS.
What else to consider
- Extra measurements: decide if you also need humidity, VOC or occupancy (PIR) from the same device, since several Produal models combine these with CO2 rather than measuring it alone.
- Commissioning: check how the transmitter will be commissioned. The room models use the MyProdual mobile app, which speeds up setting ranges and outputs on site.
For the complete Produal model list, see Carbon Dioxide Transmitters. For demand-controlled ventilation in buildings, see CO2 Sensors for HVAC & BMS.
FAQ
Common questions
What is a CO2 transmitter used for?
A CO2 transmitter measures carbon dioxide levels so a building management system can adjust fresh air based on occupancy, rather than ventilating at a fixed rate. This is the basis of demand-controlled ventilation, which saves energy in rooms that are often partly empty, such as meeting rooms and classrooms.
What CO2 range do I need?
For offices, schools and homes, a standard indoor range is enough. Where CO2 runs much higher, such as unheated spaces or process areas, choose a 10K model, which measures up to 10,000 ppm rather than the usual office range.
Should the CO2 sensor go in the room or the duct?
Put it in the room if each space needs its own control, for example a meeting room that fills and empties. Put it in the return duct if one air handling unit serves an open-plan area and an average reading for the zone is enough.
Can one device measure CO2 and temperature together?
Yes. All the Produal CO2 transmitters on this page also measure temperature as standard, and the RTX-CO2 range can add humidity, VOC and motion detection depending on the model you choose.
How does a CO2 transmitter differ from a VOC sensor?
A CO2 transmitter reports carbon dioxide, which mainly reflects occupancy. A VOC sensor responds to a wider mix of gases from cleaning products, furniture and activities, so it can pick up poor air quality even when few people are present. Many buildings use both.
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