The Ruskin® TDFi-RT (Thermal Dispersion Fan Inlet – Real Time) is a unique air measurement device for fan inlets utilizing thermal dispersion technology to establish both airflow rate and air temperature for a building’s automation system. This information allows the building’s automation system to automatically control speed of the supply, return or exhaust fans and adjust damper positions to maintain HVAC airflow requirements.

The TDFi-RT uses standoff cantilevered sensor mounting to properly position the sensors in the air stream and minimize hardware located in the fan’s inlet. This mounting concept allows the sensors to measure airflow rate by monitoring both the rate at which heat is dispersed from its heated thermistor and the overall ambient temperature of the air entering the fan from its passive thermistor. One or two sensors can be used per fan inlet. The TDFi-RT air measurement system can collect information from up to 16 fans – and even from one or more air handling units when using the BACnet network interface. On a fan array, the airflow from each individual fan can be monitored to help pinpoint a failed fan in the system.

Features of the TDFi-RT include: 

    One interface supports 1 to 16 fans with 1 or 2 sensors per fan

    Airflow measurements from 0 fpm to 10,000 fpm

    Temperature measurements from -25ºF to 140ºF

    Standoff mounting using cantilevered design

    Built-in 1-, 2- or 3-point field calibration after installation to obtain spot-on installed accuracy

    Two-line, 16-character display for easy setup, configuration and real-time airflow and temperature

The Ruskin TDFi-RT can help satisfy the requirements for minimum outside air as required by LEED (USGBC); ASHRAE 62.1, ASHRAE 90.1 and ASHRAE 189.1; California Title 24; International Mechanical Code (IMC) and the International Energy Conservation Code (IECC).

For more information about the TDFi-RT from Ruskin, visit