Evaporative cooling pad for an air treatment unit

A method for producing an evaporative cooling pad for an air treatment unit, the evaporative cooling pad comprising a first set of corrugated sheets and second set of corrugated sheets having corrugations defined in a direction transversely of a horizontal plane of the pad, the sheets of the first set being disposed alternatively with the sheets of the second set, with the corrugations of the first set crossing the corrugations of the second set;

• the crossed corrugations defining passageways penetrating from a first edge to a second edge of the pad, the corrugations of the corrugated sheets bearing against one another so that the sheets touch where at least one of the wave peaks and wave troughs of their respective corrugations cross, the method comprising the steps of:
• controlling a corrugation device for creating corrugated sheets having at least one wave peak between two wave peaks of equal amplitude of at least one of the first and second set of corrugated sheets with a lower amplitude than the wave peaks of equal amplitude and wherein the wavelength of the wave troughs on each side of the at least one wave peak with lower amplitude is shorter than the wavelength of the two wave peaks of equal amplitude on each side of the wave peak with lower amplitude;
• and
• controlling a connection operation of the first set of corrugated sheets and the second set of corrugated sheets where the corrugations of the corrugated sheets touch one another.