The main function of a central air conditioning unit is to circulate cool and fresh air in a closed room. Central air conditioning units de-humidify the air in humid conditions. There are two main types of central air conditioners: split system and cabinet based.

Split system: The split system comprises an indoor part which consists of an evaporator coil and a furnace, and an outdoor part which consists of a condenser and a compressor. The indoor part is placed or mounted on the wall inside the room, with the outdoor parts mounted outside the building.

Cabinet based: In a cabinet based central air conditioning system, all the components are placed in one cabinet. A cabinet based central system is either placed on a shelf or on the window. These types of units are small in size, but are quite efficient in cooling small buildings.

Central air conditioning units tend to work more efficiently and effectively than room air conditioning units. Central air conditioning units are very convenient and produce less noise. Central air conditioning units not only save energy but also have a longer life span if maintained properly.

One should consider the following features while purchasing central air conditioning unit:

• The unit must function without producing much noise
• Variable speed control for improved ventilation system
• High SEER (Seasonal Energy Efficiency Ratio) valve for increased effectiveness of the unit.

Most offices and homes use central air conditioning units to benefit from a better environment and lower electricity bills.