First step is to determine what the cooling requirements are. There is quite a variety of different cooling systems but they fall into two basic categories: central air conditioners and room air conditioners.

Room air conditioners are designed to cool a room, not a whole house or building, therefore, the most important is size. The room to be cooled should be measured to determine the cooling capacity of the unit. If the air conditioners cooling capacity is bigger than it needs to be, then it will be far less effective, as it will switch on and off continuously leaving the room cold and clammy.
Bellow are some types of room air conditioners:

• Window-mounted unit is available for installation in single-and double-hung windows, as well as for horizontal sliding windows and even casement windows.

Window-mounted

• Wall-mounted unit uses a sleeve to allow for through-the-wall mounting instead of window mounting.

 

Wall-mounted

• Free-standing portable unit is easily moved on casters; some require temporary ducting to the outdoors.

 

Free-standing portable

Central air conditioners are designed to cool an entire house, office building or other commercial building. These systems usually depend on ductwork to circulate the air throughout the building but ductless central air conditioners are also available. Central air conditioner installation is not a job to be taken lightly; it requires the help of a qualified contractor. Some types of central air conditioners:

• Single-package unit contains all the components and generally mounts through the wall or on the roof. Ducting to and from the unit conveys air to and from the rooms. This type is not commonly used in residential applications.

 

Single-package

• Split-system unit consists of indoor and outdoor sections. The indoor heat exchanger, or coil, mounts above the furnace, inside the ducting. The outdoor section consists of the remaining components, and the two sections are joined by refrigerant lines connecting the indoor coil to the refrigeration components in the outdoor section.

 

Split-system

• Mini-split unit is similar to a split-system but contains more than one indoor coil connected to one outdoor unit. Some mini-split units have as many as three indoor units. The efficiency of mini-split units tends to be lower than other split-systems, which needs to be taken into account when considering such a unit.

• Mini-duct unit is a central air conditioner where the indoor section is installed in the attic, and air is distributed through plastic pipes in partition walls to outlets and inlets. These units can be retrofitted in homes with electric or hydronic baseboard heating that have no ductwork.

• Water-cooled residential air conditioner can be connected to city or well water.

Water-cooled residential