There are occasions when it is physically impossible or impractical to install a central air conditioning system or heat pump. Through-the-wall and window units are noisy, drafty, and allow unneeded air infiltration when not in use that can waste energy and allow insects or other pests to invade the home or office.
Split systems offer higher efficiency and reduced noise without a large hole in the wall or an open window. By separating the compressor and condenser coil from the fan and evaporator coil, the noisiest component is away from the room. The indoor unit will usually have remote control capabilities and a timer to cycle the system only when needed. The indoor unit is called an air handler because it has the evaporator coil, blower, and controls inside. The outdoor unit is called the condenser. They are connected together with refrigerant piping and control wiring, similar to a central system.
Some manufacturers use low voltage to control the system, others use line voltage. Caution must be taken when opening up the cabinet to shut power off when servicing. The most important service item is dirt. Screens or filters can usually be found behind the front grill of the air handler. Tabs allow them to slide out for cleaning. Keep vegetation and debris away from the outdoor unit to allow good air flow for maximum cooling efficiency. An occasional blast from a garden hose with the system shut down will help keep the condenser clean.
Relatively new to the American market, ductless split systems have been in use in Japan and other markets for a long time. Until recently none were of U.S. manufacture, but increased demand changed that.
To further meet demand, some now offer gas heat as well as heat pump capabilities to increase efficiency and allow for lower design temperatures.
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