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testo 6651 - Temperature/humidity transmitter for critical climates

0555 6651
  • High system availability thanks to integrated self-monitoring and early warning
  • Ethernet, relay and analog outputs enable optimum integration into individual automation systems
  • P2A software for parametrization, adjustment and analysis saves time and money during commissioning and maintenance
  • High measuring accuracy thanks to reliable and long-term stable humidity sensor technology
  • The testo 6651 transmitter for demanding measuring tasks: In combination with the testo 660x probe series, the transmitter can master exceptionally demanding measuring tasks in air conditioning technology and numerous other fields of application.

    In combination with the testo 660x probe series, the testo 6651 transmitter is the ideal partner for carrying out sophisticated measurements in rooms, air conditioning ducts and process air.

    The testo 6651 temperature/humidity transmitter's wide range of applications:

    • Critical climate applications
    • Monitoring of comfortable climate conditions
    • Museums
    • Storing hygroscopic substances
    • Storing electronic components
    • Ripening/maturing processes (cheese, fruit, cold meats)
    • Bio research

    Technical highlights of the testo 6651 climate transmitter

    • High measuring accuracy up to ±(1.7 + 0.007 x reading)
    • Reliable and long-term stable humidity sensor
    • Ethernet*, relay and analog outputs allow for versatile use, e.g. for control purposes, for direct activation of air-conditioning units (optionally via relay), in indoor climate monitoring systems (optionally via Ethernet connection)
    • Options for self-monitoring and early warning ensure a high level of system availability
    • Robust plastic housing and water jet protection according to IP65
    • Optional 2-line display enables commissioning, adjustment and analysis without using a PC

    Enjoy all the benefits with the practical accessories

    • Wide range of high-quality digital probes available: To commission the transmitter, you need a connectable probe. Use, for example, probes with high-precision, long-term stable Testo humidity sensor for a wide range of process temperatures and environments
    • Smart probe technology: Easy probe replacement, digital interface to the transmitter, intelligent calibration concept
    • Optionally available protective probe caps for special applications (made of stainless steel, PTFE, wire mesh filter or metal)
    • Quick and easy commissioning and maintenance using the P2A software for parametrization, adjustment and analysis

    • testo 6651 humidity/temperature transmitter including instruction manual
    • Factory certificate

    Note: Please keep in mind that you need an attachable probe to commission the transmitter.

    * When using the Ethernet function, we recommend ordering the P2A software in order to be able to make the network settings.


  • Accessories
    P2A PC software
      0554 6020
    • Accessories
      Pressure-tight screw connection with PTFE ring
        0554 1796
      • Accessories
        Ethernet connector
          0554 6653
        • Accessories
          Mains unit (desktop instrument)
            0554 1748
          • Accessories
            Top-hat rail mains unit
            Top-hat rail mains unit
              0554 1749