Patent ID: 8348731

Claim:
A method for controlling an airflow device arranged for supplying or exhausting cooling air for a rack enclosure, the method comprising the steps of: disposing an opening between an area inside the rack enclosure and an area outside the rack enclosure; measuring a first temperature, a second temperature and a third temperature at locations in thermal communication with said opening, where the measured first temperature is affected by airflow through said opening, the airflow resulting from a pressure differential across said opening; determining a direction of airflow though said opening from said temperature measurement, and controlling the airflow device in response to said direction determining step; wherein a shunt tube is disposed in the opening, the first temperature is measured at a location inside the shunt tube, the second temperature is measured at a location outside the enclosure, the third temperature is measured at a location inside the rack enclosure, and wherein the direction of airflow is determined from the first, second and third temperatures measured.