Central air conditioner systems have become more sophisticated and more efficient in the last few years. The most common system is called a “split system” because part of it (the condenser) is located outside the house, and part (the evaporator) is located inside. The evaporator is mounted inside an air handler, a blower that circulates air throughout the house. For homes with forced-air heating, the furnace acts as the air handler. In these cases, the evaporator is simply mounted on top of the furnace.
Proper sizing or capacity of a system is important. Installers traditionally err on the side of over sizing a system to avoid client complaints on the hottest day of the summer, such as the system not keeping up with the heat, or the system running continuously. A larger-than-necessary air conditioning system will not function optimally. It will cool the house off quickly and then shut off. These short on-cycles are not good for two reasons:
Choosing the appropriate capacity for the air conditioning system requires a skilled and experienced air conditioning contractor that can do a heat gain calculation for your home. Some of the newest and most expensive systems available are capable of operating at two different capacities. The system operates on low most of the time, with long on-cycles that generate lots of dehumidification. If the system cannot keep up with a heat gain, it switches into a higher gear.