PURPOSE: To make it possible to carry out easily a white smoke preventative measure for winter without degrading a summer cooling capacity by installing a sprinkler device, which sprinkles cooling water into a dry type unit, to an air passage of the dry type unit.

CONSTITUTION: A sprinkler device 8 is installed to a dry type unit 2b where the sprinkler device 13 is branched from a circulation pipeline 7 which is adapted to supply cooling water to a sprinkler unit 3. The dry type unit 2b functions as a dry type unit itself if a valve 8a of the sprinkler device 8 is in a closed state so that a specified white smoke preventative capacity may be available. On the other hand, when the valve 8a of the sprinkler device 8 is opened, a part of cooling water branched from the circulation pipeline 7 is sprayed into the dry type unit 2b by way of a sprinkler hole 8c so that the dry type unit 2b functions as a wet type unit, thereby enabling the cooling capacity to be upgraded. It is, therefore, possible to carry out easily a white smoke preventative measure for winter without lowering a summer cooling capacity.