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GMW90 catalogue
CO2, Temperature and Humidity Transmitter Series GMW90
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Vaisala GMW90 Series CO₂, Temperature and Humidity Transmitters
The Vaisala GMW90 Series provides stable wall-mounted carbon-dioxide and temperature measurement, with optional humidity, for demanding HVAC and building-automation applications.
- Carbon-dioxide measurement from 0 to 5000 ppm
- CO₂ accuracy up to ±(30 ppm + 2% of reading)
- Temperature measurement from −5 to +55 °C
- Optional HUMICAP® relative-humidity measurement from 0 to 95 %RH
- Voltage, current or Modbus RTU output models
- Display and CO₂ status-indicator options
- Field-exchangeable calibrated measurement modules
- Traceable three-point CO₂ calibration certificate included
High-Quality Indoor CO₂ Measurement for Building Control
The Vaisala GMW90 Series is designed for room-level carbon-dioxide measurement in demand-controlled ventilation, green buildings and other HVAC applications where measurement stability and maintainability are important. Every model measures CO₂ and temperature; R models add relative humidity.
Vaisala CARBOCAP® technology measures CO₂ using an internal reference, supporting stable long-term operation. Exchangeable measurement modules allow maintenance and traceability to be restored without replacing the complete installed transmitter.
Select the Correct GMW90 Model
| Model | Measured parameters | Output | Local indication |
|---|---|---|---|
| GMW93 | CO₂ and temperature | Three-wire voltage outputs | No display |
| GMW93D | CO₂ and temperature | Three-wire voltage outputs | Display |
| GMW94 | CO₂ and temperature | Three-wire current outputs | No display |
| GMW94D | CO₂ and temperature | Three-wire current outputs | Display |
| GMW95 | CO₂ and temperature | Modbus RTU | No display |
| GMW95D | CO₂ and temperature | Modbus RTU | Display |
| GMW93R | CO₂, temperature and relative humidity | Three-wire voltage outputs | No display |
| GMW93RD | CO₂, temperature and relative humidity | Three-wire voltage outputs | Display |
| GMW93RA | CO₂, temperature and relative humidity | Three-wire voltage outputs | Display with CO₂ LED indicator |
| GMW94R | CO₂, temperature and relative humidity | Three-wire current outputs | No display |
| GMW94RD | CO₂, temperature and relative humidity | Three-wire current outputs | Display |
| GMW95R | CO₂, temperature and relative humidity | Modbus RTU | No display |
| GMW95RD | CO₂, temperature and relative humidity | Modbus RTU | Display |
| GMW90 | CO₂ and temperature | Configurable analogue or Modbus RTU | Configuration dependent |
| GMW90R | CO₂, temperature and relative humidity | Configurable analogue or Modbus RTU | Configuration dependent |
Choose the Measurements and Output
| Requirement | Recommended model family | Selection note |
|---|---|---|
| CO₂ and temperature only | GMW93, GMW94 or GMW95 families | Avoid paying for humidity when the control or monitoring system does not require it |
| CO₂, temperature and humidity | GMW93R, GMW94R or GMW95R families | Select an R model and provide enough receiving channels or fieldbus registers |
| Voltage outputs | GMW93 family | Confirm whether the controller accepts 0–5 V or 0–10 V and check input grounding |
| Current outputs | GMW94 family | Confirm 0–20 mA or 4–20 mA scaling and available loop resistance |
| Modbus RTU | GMW95 family | Confirm RS-485 wiring, baud rate, parity, address and termination |
| Local display | Models ending in D | Useful for commissioning and occupant-facing indication |
| Visible CO₂ status | GMW93RA | Adds display and an LED indicator for CO₂ status |
Carbon-Dioxide Measurement Performance
| Specification | GMW90 Series |
|---|---|
| Measurement range | 0 to 5000 ppm CO₂ |
| Sensor | Vaisala CARBOCAP® GM10 |
| Accuracy from +20 to +30 °C | ±(30 ppm + 2% of reading) |
| Accuracy from +10 to +20 °C and +30 to +40 °C | ±(35 ppm + 2.7% of reading) |
| Accuracy from −5 to +10 °C and +40 to +55 °C | ±(45 ppm + 3.8% of reading) |
| Five-year stability in typical HVAC applications | Total room-temperature accuracy of approximately ±75 ppm at 600 and 1000 ppm, including five-year drift |
| Default analogue scale | 0 to 2000 ppm CO₂ |
| Calibration supplied | Traceable three-point CO₂ calibration certificate |
The sensor measures up to 5000 ppm, but the standard analogue scale may be 0 to 2000 ppm. Confirm the required output scaling when the building-management system must read concentrations above 2000 ppm.
Temperature and Humidity Performance
| Parameter | Range | Best specified accuracy | Sensor |
|---|---|---|---|
| Temperature | −5 to +55 °C | ±0.5 °C from +20 to +30 °C | Digital temperature sensor |
| Relative humidity | 0 to 95 %RH | ±2.5 %RH from 0 to 60 %RH at +10 to +40 °C | Vaisala HUMICAP® 180R |
Humidity accuracy changes with humidity and temperature. Use the complete datasheet specification when assessing performance near high humidity or outside the central temperature range.
Electrical and Mechanical Specifications
| Specification | GMW90 Series |
|---|---|
| Supply voltage | 18 to 35 V DC or 24 V AC ±20%, 50/60 Hz |
| Current-output options | 0–20 mA or 4–20 mA; two- and three-channel models |
| Maximum current-output loop resistance | 600 Ω |
| Voltage-output options | 0–5 V or 0–10 V; two- and three-channel models |
| Minimum voltage-output load resistance | 10 kΩ |
| Fieldbus | Galvanically isolated RS-485 with Modbus RTU |
| Modbus address range | 0 to 247 |
| Operating temperature | −5 to +55 °C |
| Operating humidity | 0 to 95 %RH, with dew point below +30 °C |
| Enclosure rating | IP30 |
| Housing | White ABS/PC wall enclosure |
| Weight | Approximately 163 g |
| Connections | Screw terminals accepting wire up to 2 mm² / AWG 14 |
Typical GMW90 Applications
| Application | How GMW90 is used | Configuration starting point |
|---|---|---|
| Demand-controlled ventilation | Adjusts outdoor-air delivery according to occupied-space CO₂ | CO₂ and temperature with analogue or Modbus RTU output |
| Green commercial buildings | Provides stable indoor-air-quality data for the building-management system | Add humidity where comfort or moisture control is required |
| Meeting rooms and classrooms | Tracks occupancy-related CO₂ changes | Display model where occupants or facility staff need local visibility |
| Offices and public spaces | Supports ventilation optimisation and indoor-condition trending | Select output according to the installed controller |
| Museums and controlled rooms | Combines CO₂ with temperature and optional humidity | Use an R model when humidity is part of the monitoring requirement |
Compare Vaisala HVAC CO₂ Solutions
| Selection point | GMW90 Series | GMW80 Series | GMD110 | Origo10 |
|---|---|---|---|---|
| Installation | Room wall | Room wall | Ventilation duct | Wall, duct or remote-probe arrangement according to configuration |
| Main position | Higher-performance room CO₂, temperature and optional HUMICAP humidity measurement | Cost-effective room HVAC and demand-controlled ventilation | CO₂ measurement directly inside an air duct | Modular multi-parameter HVAC platform with replaceable probes |
| CO₂ range | 0 to 5000 ppm | Selected 0–2000 or 0–5000 ppm models | Up to 10,000 ppm measurement range | Depends on the selected compatible CO₂ probe |
| Humidity technology | Optional HUMICAP® 180R | Selected models use INTERCAP® | CO₂ only | Depends on the selected interchangeable probe |
| Outputs | Voltage, current or Modbus RTU | Depends on model; building-automation options available | Analogue and Modbus RTU options | Analogue, Modbus RTU or BACnet MS/TP according to model |
| Product information | Current product | Explore Vaisala GMW80 | Explore Vaisala GMD110 | Explore Vaisala Origo10 |
Vaisala GMW80 or GMW90?
| Selection point | GMW80 Series | GMW90 Series |
|---|---|---|
| Product position | Cost-efficient transmitter family for standard demand-controlled ventilation and indoor air-quality measurement | Higher-performance transmitter family for demanding HVAC and green-building projects |
| Measured parameters | CO₂-only, CO₂ + temperature, or CO₂ + temperature + humidity depending on model | CO₂ + temperature on all models, with humidity added on R models |
| CO₂ range | 0–2000 ppm on most models; selected models support 0–5000 ppm | 0–5000 ppm |
| Best CO₂ accuracy at +20 to +30 °C | Up to ±(30 ppm + 3% of reading), depending on model | Up to ±(30 ppm + 2% of reading) |
| Humidity sensor | Vaisala INTERCAP® on humidity models | Vaisala HUMICAP® 180R on R models |
| Best humidity accuracy | Designed for standard HVAC measurement; confirm the selected model's specification | Up to ±2.5 %RH from 0 to 60 %RH at +10 to +40 °C |
| Outputs | Voltage, current, relay or Modbus RTU options depending on model | Voltage, current or galvanically isolated Modbus RTU options |
| Local indication | Display or CO₂ LED indicator available on selected models | Display available on D models; GMW93RA adds a CO₂ LED indicator |
| Field maintenance | Low-maintenance CARBOCAP® design; service arrangement depends on model | Field-exchangeable calibrated CO₂, temperature, and humidity/temperature modules |
| Choose GMW80 when | A cost-effective standard HVAC solution provides the required range, output and accuracy | — |
| Choose GMW90 when | — | The project needs a consistent 0–5000 ppm range, stronger measurement accuracy or exchangeable calibrated modules |
| Product information | Explore Vaisala GMW80 | GMW90 models are detailed on this page |
Exchangeable Modules and Calibration
| Module | Used for | Maintenance role |
|---|---|---|
| GM10SP | CO₂ measurement | Factory-calibrated replacement CO₂ module |
| TM10SP | Temperature in CO₂ + T models | Replacement temperature module for the applicable model |
| HTM10SP | Humidity and temperature in CO₂ + T + RH models | Replacement HUMICAP humidity and temperature module |
The exchangeable modules support efficient field maintenance, but the replacement must match the transmitter model and measurement configuration. Calibration checks can also be performed with suitable reference equipment and the applicable Vaisala procedure.
Vaisala GMW90 Supplier and Technical Support in Malaysia
Seacom Process Instruments supplies and supports the Vaisala GMW90 Series CO₂, temperature and humidity transmitters in Malaysia for demand-controlled ventilation, green buildings, offices, meeting rooms, classrooms and demanding HVAC applications.
Our team can help select the measured parameters, voltage, current or Modbus RTU model, display option, analogue scaling and suitable installation location. We can also assist with commissioning, reference checks and replacement measurement modules.
Selecting a GMW90 model? Send us the room type, expected occupancy, required CO₂ range, temperature and humidity requirements, controller input, supply voltage, display preference and building-management protocol.
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The Vaisala GMP343 is a rugged, high-accuracy carbon-dioxide probe for outdoor monitoring, ecological research, soil respiration, plant-growth chambers and demanding OEM applications.
- Selectable CO₂ ranges from 0–1000 ppm to 0–2%
- Diffusion-aspirated or flow-through sampling models
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- Temperature, pressure, humidity and oxygen compensation
- RS-232, RS-485, 4–20 mA, 0–2.5 V or 0–5 V outputs
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- IP67 probe housing with the cable connected
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The Vaisala GMD110 measures carbon dioxide directly inside ventilation ducts for precise HVAC control and demand-controlled ventilation.
- CO₂ measurement range from 0 to 10,000 ppm
- Accuracy of ±40 ppm from 0 to 3000 ppm
- 4–20 mA, 0–5 V, 0–10 V or Modbus RTU output options
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- Traceable calibration certificate included
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- Discontinued product; not recommended for new purchases
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- GMP222 probes for ppm-level CO₂ up to 10,000 ppm
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- Use Vaisala Indigo80 for new portable measurement systems
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