The air conditioning humidity transmitter – Testo 6621

Model No: Testo 6621

The air conditioning humidity transmitter

  • Transmitter with 2 analog outputs (temperature/humidity)
  • High-precision Testo humidity sensor with long-term stability
  • Optional 2-line LCD display
  • P2A software for parameterization, adjustment and analysis.


Adjustment on-site: Fast and precise via the external interface!

Of interest not only to in-house technicians or Facility Managers, but increasingly also to the responsible plant constructors: Which follow-on costs arise as a result of this transmitter?
Good news from Testo: The testo 650 or testo 400 reference instruments can be connected using the adapter 0554 6022 via the external interface – without opening the transmitter. A few operating steps in the testo 400 or testo 650 menu suffice to adjust the testo 6621 transmitter. Conclusion: Saved time and lower operating costs!

A broad variety of the testo 6621 transmitter is available. Depending on the application in a room or in a duct, the corresponding designs can be selected. A display and an external probe are available as options. You can choose between the housing colours grey and white. The testo 6621 is persuasive in technical terms thanks to the patented humidity sensors that guarantee the highest accuracy. The sensors and the analog outputs can be adjusted, analyzed and parameterized via the external interface using the P2A software.
The testo 6621 is a high-performance transmitter for a low price. It meets the increasing requirements in automated building services in terms of accuracy, reliability and safety and thereby saves energy costs.

– Highly accurate testo humidity sensor with long-term stability (±2.0% RH)
– Optional 2-line LCD display
– P2A software for parameterization, adjustment and analysis, saves time and costs in commissioning and maintenance
– Optimum calibration concept thanks to adjustment of the entire signal chain (1-point, 2-point and analog adjustment)
– Adjustment without dismantling the transmitter
– 2 analog outputs (humidity/temperature), option of 1 passive humidity and temperature analog output

Delivery Scope

testo 6621 temperature and humidity transmitter as a wall or duct version, with selectable signal outputs, 2-line display (optional), external interface for adjustment and commissioning.


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