Air conditioning history

In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. After graduating from Cornell University, Carrier, a native of Angola, New York, found a job at the Buffalo Forge Company. While there, Carrier 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, and the first “air conditioner”, designed and built in Buffalo by Carrier, began working on 17 July 1902.
Designed to improve manufacturing process control in a printing plant, Carrier’s invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. 

He built a box in which he could trap air and control what happened to it inside. He then gathered together a couple of fans, a garden sprayer and heating coils. He used one fan to suck the air through the heating coil into the box, then he lower the temperature of that air with the spray of cold water, as the air passed through the water it turned into fog. Carrier have now got 100 percent relative humidity, he then began reducing the level of humidity by adding a precise amount of dry air to the chamber so as to reduce a relative humidity …