These are free-standing, easy to move air conditioners that you can move from room to room. Because they need to vent hot air somewhere else, portable air conditioners are generally set up in windows and come with their own window kit. These are ideal for people who live in small spaces and/or only use air conditioning sporadically. They can be the most cost-efficient option since they only cool off one particular area instead of an entire home space. Some options even work double-duty by including heat so you can use it year-round. Traditionally found in college apartments and dorm rooms, today’s window air conditioners are energy efficient, quiet and overall easy on the eyes. They can be installed in any room with a window that leads to the outside and works by filtering hot air from inside outside through the window. Window air conditioners tend to feature a fan option, heater and programmable timer. They are an efficient and economical option for small spaces. Wall air conditioners look similar to window units with the exception that they are mounted on an outdoor wall and therefore filter hot air outside through the wall instead of a window.

They tend to be more energy efficient than window units because they create an airtight seal that keeps hot air outside. One main difference is that these units are actually built into the wall, whereas window units can be installed and taken down. They are therefore a more permanent option than window units. Unlike portable, window or through the wall units, the ductless mini-split model is not an actual unit that can be installed in one room or another. air handling unit sizing softwareThey are capable of cooling more than one room at a time, similar to central units, but they don’t require ductwork. low power ac/dc converterThey are made up of two main parts: a large condenser unit that needs to be installed outside and one (or more) compact blower units that can be mounted on the wall or ceiling. through wall air conditioner dimensions

These mounted units are placed strategically inside the rooms or zones you want and can be controlled separately, so you can only cool the spaces you are using to save energy costs. Central air conditioning units are popular for homeowners who need to cool several rooms at the same time. These systems are fully ducted, making them a more expensive option than portable or split units but can be the best choice overall for larger homes. They work by first extracting warm air from all over your house to cool at a central point and then distributing that cool air to your house through a series of vents and ducts. The hot air is then filtered outside. Packaged Terminal Air Conditioner (PTAC) Commonly found in hotel and motel rooms, senior living facilities, hospitals, condominiums and apartment buildings, PTACs are an all-in-one air conditioner/heating unit. They are commonly installed in walls and windows. Should air-conditioning go global, or be rationed away? July 17, 1902: It was another scorcher in New York.

The week before, seven deaths tied to the heat had been reported. The city’s public baths were jammed with people desperately trying to cool down. The newspapers, following President Theodore Roosevelt’s vacation on Long Island, said he had been out horseback riding when a thunderstorm rolled in. It was so hot, he did not mind getting soaked. What the newspapers did not report was that something had happened involving the second floor of a Brooklyn printing plant — something that changed everything. What happened was air-conditioning. July 17 was the date on the blueprints for newfangled equipment to temper the air. A junior engineer from a furnace company figured out a solution so simple that it had eluded everyone from Leonardo da Vinci to the naval engineers ordered to cool the White House when President James A. Garfield was dying: controlling humidity. “If you could keep humidity at a balanced rate,” said Marsha E. Ackermann, the author of “Cool Comfort: America’s Romance With Air-Conditioning” (Smithsonian Books, 2002), “it would not seem so sweltering and things would not be dripping all over.”

It was a world-changing innovation. “Air-conditioning, in the broad sense, had a profound effect on the way people lived and worked,” said Bernard A. Nagengast, an engineering consultant who specializes in the history of air-conditioning and heating. “It allowed industry to operate in ways it couldn’t operate before, in places it couldn’t operate before.” It all but redefined Florida and Houston and the rest of the Sun Belt. “And Singapore, sometimes called the air-conditioned nation,” said Eric B. Schultz, a former Carrier Corporation executive and author of a recently published company history. And, Mr. Schultz said, the Internet, because air-conditioning minimized dust, making possible the so-called clean rooms for computer manufacturers and electronics companies. In time there would be window-mounted air-conditioners to drip on people on the sidewalk below (or fall out and cause injuries). And there would be brownouts in the summer as air-conditioners put a strain on power plants.

But in 1902, there was a printing plant, and a problem. The plant, on Metropolitan Avenue in East Williamsburg, had just been completed, Mr. Nagengast said. It was built for a company that printed the humor magazine Judge, which carried fanciful illustrations. The printing company had to run each page of the magazine through the press once for each color on the page. Sometimes one color was printed one day, and another color the next. The problem was that paper would absorb moisture from the sticky Brooklyn air and expand by a fraction of an inch, enough so that the colors would not line up properly. Worse, he said, “the ink refused to dry fast enough.” And the printer could not wait. There was a schedule. There were subscribers who expected the next issue to land in their mail boxes, no matter what. “They were doing an issue a week,” Mr. Nagengast said. The junior engineer who tackled the problem was Willis Carrier, who went on to start Carrier Corporation.

The solution he devised involved fans, ducts, heaters and perforated pipes. Mr. Schultz said the equipment, installed later in the summer of 1902, controlled the humidity on the second floor of a short building at Metropolitan Avenue and Morgan Avenue. That structure backs up to a taller building that the printing company, Sackett & Wilhelms, also used. Carrier’s plan was to force air across pipes filled with cool water from a well between the two buildings, but in 1903, he added a refrigerating machine to cool the pipes faster. American Heritage magazine called Carrier “a Johnny Icicle planting the seeds of climate control all across America.” A paper mill in 1906, a pharmaceutical plant in 1907, a movie-processing plant in 1908, a tobacco warehouse in 1909, a candy manufacturer in 1909, a bakery in 1911. As at the printing plant, humidity had made hot-weather work unpleasant if not impossible. “Carrier was not happy with the pipes,” Mr. Schultz said, and a couple of years later he had a brainstorm that Mr. Schultz called “one of Carrier’s essential genius insights,” a system that worked far better.

“This is all leveraging off the work done at Sackett & Wilhelms,” Mr. Schultz said. “This allows him to say the principle is right. It allows him to say, ‘Instead of blowing across metal pipes which can frost, I can blow it through water,’ and that becomes the principle that they use at the Rivoli” — a movie theater on Broadway that was air-conditioned in 1925 — and “at Madison Square Garden.” Carrier’s equipment is long gone from the Sackett & Wilhelms compound. Since 2008, the Sackett & Wilhelms buildings have been the headquarters of the International Studio and Curatorial Program and home to 100 foreign artists and curators in residency programs. The second floor, where Carrier’s invention was tried out, has been divided into studios and gallery space. There is no more central air-conditioning there now than there was on July 16, 1902, the day before Carrier dated his blueprints. More than a dozen air-conditioners stick out from windows on the second floor.