To surely prevent a watering mechanism including a spray nozzle from freezing in a cold period and to always exhibit a designed ability of a free cooling chiller by raising a utilization ratio of the watering mechanism for operation even in the cold period.
The invention includes a connection port 7 which can connect a supply source 100 of compressed air Ap, an air supply circuit 8 which connects the connection port 7 to the downstream side of a water supply valve 9 which supplies or stops water to at least spray nozzles Ns via an air supply valve 8v which supplies or stops the compressed air Ap, and a control system Mc having a compressed air supply control function which not only switches the air supply valve 8v to the closing side to control the water supply valve 9 opened or closed at least when an ambient temperature To exceeds a set temperature Ts but also switches the water supply valve 9 to the closing side when the ambient temperature To stays at a set temperature Ts or below and is switched to the closing side after the air supply valve 8v is switched to the opening side only for a set time Zs.
NAKAJIMA TAKAHISA
YAMAZAKI OSAMU
KATAGIRI TOMOMI
