In a central air-conditioning system, all the components of the system are grouped together in one central room and conditioned air is distributed from the central room to the required places though extensive duct work. The central air-conditioning system is generally used for the load above 25 TR and 2500cubic meter/min of conditioned air. The central plants require the following components and all the components are assembled on the site:-

(A) Cooling and de-humidifying coils 

(B) Heating coils 

(C) Blower with motor 

(D) Sprays for cooling, de humidifying or washing 

(E) Air-cleaning equipments 

(F) A control device.

The central system serves different rooms through extensive duct work with individual control. The system may use one of the following methods to supply the conditioned air.

(a) Air-is conditioned in the center conditioned room and is supplied to the required rooms with controlled air- discharge in each room. 

(b) The water is chilled in the central conditioned room and is supplied to the required room with individual flow control.

Individual evaporator in each room with thermostatic flow control or direct expansion system.