Timeline of United States inventions (1890–1945)
Air conditioning is the cooling and de-humidification of indoor air for thermal comfort. Using a system of coils as a solution to cool and remove moisture from muggy air in a printing plant that was wrinkling magazine pages, Willis Carrier invented and manufactured the world's first mechanical air conditioning unit in 1902. Carrier's invention – encompassing the first system to provide man-made control over temperature, humidity, ventilation and air quality, was first installed as a solution to the quality problems experienced at a Brooklyn printing plant, Sackett-Wilhelms Lithographing and Publishing Company. Air conditioning not only spawned a company and an industry, but also brought about profound economic, social and cultural changes.
Packaged terminal air conditioner
Although PTACs are used mostly to heat or cool a single living space using only electricity (with resistive and/or heat pump heating), there are cooling-only PTACs with external heating through a hydronic heating coil or natural gas heating. Typical PTAC heating and cooling capacity values range from 2 to 5.5 kilowatts (7,000–19,000 BTU/h) nominal. One characteristic of PTACs is that condensate drain piping is not required because the condensate water extracted from the air by the evaporator coil is drawn by the condenser fan onto the condenser coil surface where it evaporates. Conventional PTACs still require condensate drain piping to be installed. The first practical semi-portable air conditioning unit was invented by engineers at Chrysler Motors and offered for sale starting in 1935.