The Vaisala GMD110 measures carbon dioxide directly inside ventilation ducts for precise HVAC control and demand-controlled ventilation.
The Vaisala GMD110 is a duct-mounted carbon-dioxide transmitter for air-handling systems and demand-controlled ventilation. Its sensing head measures directly inside the duct, avoiding external sampling tubes and reducing the risk of errors caused by leaks or incorrect sample-flow direction.
Vaisala CARBOCAP® technology provides stable CO₂ measurement in demanding HVAC environments. The sensor head is heated during operation to reduce condensation risk, while the IP65 enclosure protects the electronics from dust and water jets.
| Requirement | Order selection | Important check |
|---|---|---|
| 4–20 mA | Current-output version | Requires 20 to 30 V DC; maximum loop load is 500 Ω |
| 0–5 V | Voltage-output version with 0–5 V selection | Requires 12 to 30 V DC; receiving input must have at least 10 kΩ load resistance |
| 0–10 V | Voltage-output version with 0–10 V selection | Confirm the building controller input and common grounding arrangement |
| Modbus RTU | RS-485 version | Confirm network wiring, baud rate, parity, device address, termination and biasing |
| Normal occupied-space HVAC | 0–2000 ppm analogue scale | Use when the expected duct concentration remains within the standard ventilation range |
| Elevated CO₂ | 0–5000 ppm analogue scale | Provides more headroom while retaining useful analogue resolution |
| Full measurement range | 0–10,000 ppm analogue scale | Use only when the process can approach higher concentrations |
Scaling matters: Every GMD110 measures from 0 to 10,000 ppm, but an analogue unit is ordered with a defined output scale. Match that scale to the controller configuration and expected CO₂ concentration.
| Specification | GMD110 |
|---|---|
| Measurement range | 0 to 10,000 ppm CO₂ |
| Accuracy from 0 to 3000 ppm | ±40 ppm CO₂ |
| Accuracy from 3000 to 10,000 ppm | ±2% of reading |
| Typical calibration uncertainty at 2000 ppm | ±31 ppm CO₂ |
| Typical calibration uncertainty at 10,000 ppm | ±105 ppm CO₂ |
| Start-up time at +25 °C | Less than 12 seconds |
| Warm-up time for full specification | Less than two minutes |
| Response time | Less than one minute, T90 |
| Sensor technology | Vaisala CARBOCAP® non-dispersive infrared sensor |
| Calibration supplied | Traceable calibration certificate |
The stated accuracy applies at +25 °C and 1013 hPa and includes repeatability and non-linearity. Temperature and pressure influence should be considered when the duct conditions differ substantially from the reference conditions.
| Specification | GMD110 |
|---|---|
| Output parameter | Carbon dioxide in ppm |
| Current output | 0 or 4 to 20 mA, scalable; maximum load 500 Ω |
| Voltage output | 0 to 5 V or 0 to 10 V, scalable; minimum load 10 kΩ |
| Digital output | RS-485 with Modbus RTU |
| Supply for current output | 20 to 30 V DC |
| Supply for voltage output or RS-485 | 12 to 30 V DC |
| Power consumption | 0.5 W typical; 1.1 W maximum |
| Operating temperature | −20 to +60 °C |
| Operating humidity | 0 to 95 %RH, non-condensing |
| Enclosure rating | IP65 |
| Probe dimensions | 25 mm diameter and 126 mm length |
| Weight | Approximately 215 g |
| Mounting | Screws or optional 243261SP mounting flange |
| Terminal wire size | 0.5 to 2.5 mm² / AWG 24 to 14 |
| Application | How the measurement is used | Selection consideration |
|---|---|---|
| Demand-controlled ventilation | Controls outdoor-air delivery according to duct CO₂ concentration | Choose an output and range matching the building controller |
| Return-air monitoring | Provides a combined indication of CO₂ returning from occupied zones | Confirm that the return-air location represents the intended area |
| Air-handling units | Supplies CO₂ data for ventilation control, alarms and trending | Modbus can reduce analogue wiring where the controller supports RS-485 |
| Commercial buildings | Supports indoor-air-quality and energy-efficiency strategies | Use room transmitters when zone-level measurement is required |
| Hospitals and critical facilities | Provides traceable duct CO₂ measurement for demanding HVAC systems | Define calibration and verification intervals in the maintenance plan |
| Tool | Connection | Use |
|---|---|---|
| Vaisala Insight PC software | USB2 adapter with M12-to-M8 service cable 262195SP | Configuration, diagnostics and CO₂ adjustment |
| Vaisala Indigo80 | M12-to-M8 cable 262195SP | Portable display, configuration and field adjustment |
| Vaisala MI70 | MI70 connection cable 219980SP | Portable display and supported service functions |
| Calibration adapter | DRW244827SP | Controlled reference-gas delivery during calibration work |
The service port is intended for temporary configuration and servicing connections, not permanent system communication. Return the output-mode switch to the required operating position after service work.
| Selection point | GMD110 | GMD20 Series |
|---|---|---|
| Project use | Preferred Vaisala duct CO₂ transmitter for new installations | Discontinued legacy transmitter |
| CO₂ range | 0 to 10,000 ppm measurement range | Nominally 0 to 2000 ppm; other ranges required recalibration |
| Accuracy | ±40 ppm from 0 to 3000 ppm | ±(2% of range + 2% of reading) |
| Outputs | 4–20 mA, 0–5 V, 0–10 V or Modbus RTU | 0–20 mA, 4–20 mA and 0–10 V; optional relay or LonWorks |
| Supply | 12 to 30 V DC or 20 to 30 V DC, depending on output | Nominal 24 V AC/DC |
| Operating temperature | −20 to +60 °C | −5 to +45 °C |
| Calibration | Traceable calibration certificate supplied; Insight, Indigo80 and MI70 service support | Legacy field-check and calibration arrangement |
| Product information | This page details GMD110 | Review legacy Vaisala GMD20 |
Replacing a GMD20? Check the old supply, signal, scaling, display or relay requirement and duct mounting before ordering. GMD110 is the suitable starting point, but it is not a blind terminal-for-terminal replacement.
| Product | Installation | Choose it when |
|---|---|---|
| GMD110 | Ventilation duct | You need direct, high-accuracy duct CO₂ measurement with analogue or Modbus output |
| GMW80 Series | Occupied-room wall | You need a cost-effective room transmitter with model-specific temperature, humidity and output choices |
| GMW90 Series | Occupied-room wall | You need higher-performance room CO₂, temperature and optional humidity measurement |
| GMP252 | Machine, chamber, process or custom assembly | You need a standalone ppm-level probe for demanding conditions rather than a dedicated duct enclosure |
| GMP251 | Incubator, chamber or percentage-level process | You need percentage-level CO₂ measurement |
| Product information | Explore Vaisala GMW80 Explore Vaisala GMW90 Explore Vaisala GMP252 Explore Vaisala GMP251 | |
Seacom Process Instruments supplies and supports the Vaisala GMD110 Duct CO₂ Transmitter in Malaysia for air-handling units, ventilation ducts, commercial buildings, hospitals, data centres and other demanding HVAC applications.
Our team can help select the 4–20 mA, 0–5 V, 0–10 V or Modbus RTU version, confirm the required CO₂ scaling, review the duct location and specify suitable mounting, configuration and service accessories. We can also assist with GMD20 replacement planning, commissioning and calibration.
Selecting or replacing a duct CO₂ transmitter? Send us the expected CO₂ range, duct size, air velocity, operating temperature, supply voltage, controller input, communication protocol and details of any existing instrument.
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The Vaisala GMD110 measures carbon dioxide directly inside ventilation ducts for precise HVAC control and demand-controlled ventilation.
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