Ductless air conditioners are the ones that do not involve the presence of a central duct. Normally the ductless air conditioning systems have a simple layout, it consists of the outdoor refrigeration unit consisting of various refrigeration pipes that cool air and the refrigerant gasses connected to fan unit. The air conditioners having ducts have a different layout altogether, every room has an air outlet from where the air is given out, the air outlet is connected to the external air conditioning unit by a duct, located quite a distance away.

The evolution of the ductless air conditioning systems has been quite slow, initially we had the window air conditioners where the central duct was not present, the fan unit was placed inside the room and the fan unit combining all the refrigeration tubes and gasses were placed outside. The indoor fan unit and the outdoor refrigeration unit were placed beside each other and are not separated.

The next evolution of the ductless air conditioners were the split air conditioners, these were consisting of two separate units, the exterior/outdoor unit housing the fans and the refrigeration units, connected using a pipe to the fan unit present within the room. The advantage of the split air conditioners over the window air conditioners is that they could be connected with multiple fan units to a single outdoor unit.

The advantages of using the split air conditioners over duct air conditioners are many. The operation of the split air conditioners are quiet, they do not make as much noise as the duct air conditioners. Construction of ducts is expensive and requires a lot of modifications within the room, the cost can further escalate if another room is added, whereas the split ac's can be conveniently placed and no modifications are required in the construction. Functionality of the split ac's can be controlled they can be activated or disabled according to the need whereas the air conditioners having ducts cannot be controlled due to the absence of any regulation at the outlet and the air conditioning is wasted in certain rooms where it's not needed.

The spilt air conditioners are perfectly suited for the places having hot and humid climate for some months of the year. Its efficiency and construction make it sensible and affordable to own.