AIR-CONDITIONER

PURPOSE: To perform communication between a controller on the centralized control part arranged in a management room and a controller for an apparatus on the air- conditioning zone side in a number of air-conditioning zones without a signal wire, in a large scale air-conditioning device. CONSTITUTION: An air-conditioner comprises the common proper-number of heat source machines 1, the proper number of apparatuses on the air-conditioning side installed respectively in a number of air-conditioning zones, a cold hot water piping 4 through which the heat source machine is connected to each apparatus on the air-conditioning zone side, and a centralized controller 7 installed at a centralized control part arranged in a proper place and concentratedly control the apparatus on the air-conditioning zone. In the air-conditioner, an acoustic transmitter-receiver 15a is installed to each of the cold hot water pipings of the apparatus on the air-conditioning zone side and connected to each of the controllers. An acoustic transmitter receiver 15b is installed to the cold hot water piping of a centralized control part and connected to the centralized controller. Communication between the controller of the apparatus on the air- conditioning zone side and the centralized controller is effected through an acoustic transmitter receiver by an acoustic wave propagated through water in the cold hot water piping through the acoustic transmitter receiver.