The testo 6621 air conditioning transmitter is specially designed for use in air conditioning technology. This particularly includes the regulation and monitoring of air conditioning in buildings such as office buildings, museums, hotels, hospitals, as well as air conditioning in storage and production facilities.
The product is placed in the lower price range and is equipped with the features important for the application range as well as some new, beneficial features:

• An attractive, simple design, ideally suited for use in public view
• The reliable, tested Testo humidity sensor
• Fast and easy on-site adjustment with Testo handheld instruments (types testo 400 and testo 650)
• Easy-to-use P2A software for parameterization or adjustment

The product is not suitable for high-humidity drying processes (relative humidity constantly over 90%); please refer to the hygrotest versions for applications of this nature.

• Accuracy of ±2.5 % RH
• Wall or duct version, option of 2-line LCD display
• Commissioning and maintenance through external interface (mini-DIN) and Testo P2A software saves time
• Testo humidity sensor with long-term stability
• High-quality design
• Optimum calibration concept with
  • adjustment of entire signal chain, including analog adjustment, without dismantling the transmitter
  • 1-point adjustment can be performed on-site easily and quickly using t400 or t650
  • 2-point adjustment using Testo P2A software
• Parameterizing, adjusting and analyzing software (P2A) for setting up, adjusting and analyzing the transmitter
  • Parameterization of unit and scale
  • Adjustment (1-point, 2-point, analog adjustment)
  • Reset to factory settings
  • Testing of analog outputs
  • Requesting of max./min. values
  • Parameterization and adjustment history (all activities of the P2A software are registered in the PC)
  • Serial number and firmware version can be called up
• 2 analog outputs (% RH & °C or °F)