In a central air-conditioning system, refrigerant is pumped from an outdoor condenser coil unit into an indoor unit from which cooled air is distributed to each room in the house through a system of ducts. Many factors will contribute to the optimal performance and durability of your central air conditioning system.
One of the most important of these is the size of the unit, which is actually the cooling capacity measured by the BTUs against the size of the space to be cooled and other factors which go well beyond a simple calculation of square footage. You'll want to ensure that your professional contractor uses the industry guidelines in sizing your air conditioner for your environment, which is also referred to as residential load calculation.
Before replacing or installing a new central air system, the ducts throughout your home should be examined for leakage, blockage and proper insulation. Problems with airflow through the ducts will cause your air conditioner to work harder and less efficiently, and will reduce the life of the system.
Placement of both the inside and outside components is also important for efficient operation. The outdoor component should be placed in a shaded area, with sufficient space around it to allow proper airflow and access for maintenance.
The inside component should be placed in a conditioned or well-insulated room, and there are many non-mechanical ways of reducing the work your air conditioner must do to maintain a comfortable environment that involve blocking and reflecting heat that enters the house through windows, doors, the roof and attic.
Blocking and reflecting sunlight before it enters through windows can reduce heat gain. Providing shade around windows with trees or awnings or closing drapes and blinds against the sunlight can reduce the amount of heat actually entering a room.