Vaisala HMW90 High-Accuracy Humidity and Temperature Transmitter

The Vaisala HMW90 Series provides high-accuracy humidity and temperature measurement for demanding indoor HVAC and controlled-environment applications.

  • Humidity accuracy up to ±1.7% RH
  • Analog or Modbus RTU output models
  • Optional display and configurable relay
  • Replaceable measurement module with calibration certificate

Vaisala HMW90 Humidity and Temperature Transmitter

The wall-mounted Vaisala HMW90 Series provides accurate and stable humidity and temperature measurement for indoor environments where standard HVAC transmitters may not provide sufficient performance or calibration documentation.

Typical applications include data centres, laboratories, museums, archives, production areas, warehouses and testing facilities. The series offers current, voltage and Modbus RTU models, with optional displays and configurable versions for special output scaling or calculated humidity parameters.

High-Accuracy Indoor Measurement

The HMW90 measures relative humidity across the full 0–100% RH range with accuracy up to ±1.7% RH from 0–90% RH within the specified central temperature range. Temperature accuracy reaches ±0.2 °C under normal indoor conditions.

The Vaisala HUMICAP® 180R sensor provides dependable long-term stability for demanding building-automation applications. Each humidity transmitter is supplied with a traceable calibration certificate to support commissioning, quality records and planned calibration programmes.

Flexible Outputs and Configurations

The HMW90 family includes loop-powered 4–20 mA models, voltage-output models and Modbus RTU models. Versions with a visible local display are available, while selected voltage-output models can also provide a configurable relay.

Depending on the model and configuration, output parameters can include relative humidity, temperature, dew point, mixing ratio, enthalpy, wet-bulb temperature, dew-point depression and absolute humidity.

Replaceable Measurement Module

The humidity and temperature measurement module can be replaced in the field, reducing downtime when calibration or maintenance is required. Configuration, installation and field adjustment are designed to be straightforward for building-automation technicians.

The replacement module and transmitter configuration must match the required measurements, outputs and scaling. Calibration intervals should be determined according to the application conditions, required uncertainty and quality-system requirements.

Key HMW90 Series Features

  • 0–100% RH measurement range
  • Humidity accuracy up to ±1.7% RH
  • Temperature accuracy up to ±0.2 °C
  • Current, voltage and Modbus RTU model options
  • Optional local display
  • Configurable relay on selected voltage-output models
  • Calculated humidity-parameter options
  • Field-replaceable humidity and temperature module
  • Traceable calibration certificate included
  • White and alternative enclosure-colour options

Individual HMW90 Series Models

Select the model according to the measured parameters, building-management-system input and whether a local display or relay is required.

ModelMeasurementOutputDisplayRecommended use
HMW92 Humidity and temperature 4–20 mA current outputs No Loop-powered building-automation systems
HMW92D Humidity and temperature 4–20 mA current outputs Yes Loop-powered systems requiring local indication
HMW93 Humidity and temperature Voltage outputs No Voltage-input controllers; configurable relay available
HMW93D Humidity and temperature Voltage outputs Yes Voltage-input controllers requiring display or relay
HMW95 Humidity and temperature Modbus RTU No Digital building-automation integration
HMW95D Humidity and temperature Modbus RTU Yes Digital integration requiring local indication
HMW90 Humidity and temperature Configurable analog or digital arrangement Configuration dependent Special scaling or calculated-parameter requirements
TMW92 Temperature only 4–20 mA current output No Loop-powered temperature measurement
TMW93 Temperature only Voltage output No Voltage-input temperature measurement
TMW90 Temperature only Configurable output Configuration dependent Special temperature scaling requirements

Model-number guide: choose HMW92 for 4–20 mA, HMW93 for voltage output or HMW95 for Modbus RTU. Add D when a local display is required. Select an HMW90 configurable model for special scaling or calculated parameters, and a TMW model when only temperature is required.

Vaisala HMX80, HMX110, HMW90 or XMW85 Series?

These Vaisala HVAC transmitter families serve different measurement and control requirements. Choose according to accuracy, mounting location, communication method, calibration documentation and whether carbon-dioxide measurement is required.

Selection pointVaisala HMX80 SeriesVaisala HMX110 SeriesVaisala HMW90 SeriesVaisala XMW85 Series
Product position Cost-effective routine HVAC Balanced high-accuracy HVAC Premium indoor wall measurement Smart indoor Modbus and air-quality measurement
Measured parameters Humidity and temperature; temperature-only models available Humidity and temperature; temperature-only models available Humidity and temperature; temperature-only models available Humidity and temperature, with optional CO₂ measurement
Humidity accuracy Up to ±3% RH Up to ±2% RH Up to ±1.7% RH Up to ±3% RH
Installation options Indoor wall, duct, humid-area wall and outdoor Indoor wall, duct and outdoor Indoor wall only Indoor wall only
Output and communication Current, voltage or Modbus RTU, depending on model 4–20 mA or Modbus RTU, depending on model Current, voltage or Modbus RTU, depending on model Modbus RTU on all models
Local display Available on selected models No display on standard models Available on selected models Available on selected models
Calibration certificate Not supplied Traceable certificate included Traceable certificate included Confirm according to selected model and project requirement
Main reason to choose Simple, economical measurement across multiple mounting styles Better accuracy and documentation for demanding HVAC locations Highest humidity accuracy for an indoor wall transmitter Modbus integration or combined CO₂, humidity and temperature measurement

Quick selection: choose the 80 Series for routine HVAC where cost and mounting flexibility are the priorities. Choose the 110 Series when better accuracy and a traceable certificate are required for wall, duct or outdoor measurement. Choose HMW90 for premium indoor wall measurement. Choose XMW85 for indoor Modbus systems, especially when CO₂ must be measured with humidity and temperature.

Common HMW90 Applications

  • Data centres and critical equipment rooms
  • Laboratories and testing environments
  • Museums, archives and collections storage
  • Pharmaceutical and medical-device facilities
  • Production areas and controlled warehouses
  • Demanding indoor HVAC and building automation

Information Required for HMW90 Selection

Before ordering, confirm the required measurement parameters, 4–20 mA, voltage or Modbus RTU interface, display requirement, relay function, output scaling, operating range, enclosure colour and calibration requirements.

For existing installations, provide the current model number, wiring, controller input and output scaling. This helps ensure that the replacement model matches both the electrical arrangement and building-management-system configuration.

Humidity Monitoring for Data Centres

Planning measurements for server rooms or air-handling systems? Explore sensor placement, relative humidity, dew point and monitoring-system requirements.

Read our data centre humidity and temperature monitoring guide

Vaisala HMW90 Supplier and Technical Support in Malaysia

Seacom Process Instruments supplies and supports the Vaisala HMW90 Humidity and Temperature Transmitter in Malaysia for data centres, laboratories, museums, archives, controlled warehouses and demanding HVAC applications.

Our team can assist with model selection, output type, display, relay, calculated parameter, special scaling, installation location, controller integration and calibration planning.

Contact Seacom with your required humidity and temperature accuracy, building-management-system interface, display requirement and application conditions so we can recommend a suitable HMW90 configuration.

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