To provide a duct replacing method for installing a temporary duct having high sealing property simply in a short time even in a small space, reducing time and the number of stopping operation of an air conditioning system or a ventilating system, and dispensing with formation of an end connection for connecting the temporary duct with an existing duct and use of fire in work for connecting the temporary duct with the existing duct.
In a first process, temporary duct panels 20as are carried in through an inspection port 18, and smaller temporary duct 20 is assembled and installed inside the existing duct 16a in a scope of replacement. Next, while performing operation of the ventilating system by the temporary duct 20, the existing duct 16a in the scope of replacement is removed in a second process. In a third process, a new duct is installed in a section from which the existing duct is removed. In a fourth process, the temporary duct 20 is dismantled and the temporary duct panels 20as are removed while the ventilating system stops again.
UENO YUTAKA
KUNIYASU HIDEKAZU
