Air conditioning
In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. After graduating from Cornell University, Carrier found a job at the Buffalo Forge Company. There, he began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. The first air conditioner, designed and built in Buffalo by Carrier, began working on 17 July 1902.
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.