HVAC Time Line

1998-2000 by Steven J. Wolfe, CM, SSAW Home Services Company, all rights reserved.

Before 1900 | 1900 to 1929 |1930 to 1940 |1941 to 1998
Full screen version
The Early Years -- 1745 to 1900



William Cullen, in Scotland, initially developed the concept of mechanical / chemical refrigeration. (Up until almost the 20th century, early refrigeration consisted solely of using natural ice for food preservation.)


William Cullen cooled water by drawing a vacuum over it. This was the earliest known attempt at vapor compression refrigeration.


The principles of absorption were discovered.


Thomas Moore builds a box-within-a-box for the sole purpose of preserving food and calls it the "refrigerator."


Oliver Evans proposed a closed circuit vapor compression system.


Artificial ice was made for the first time in an experiment


Michael Faraday discovers the principle of absorption type refrigeration.


Jacob Perkins patents an ice-producing machine.
Artificial ice manufacturing becomes practical.


Jacob Perkins, an American engineer, invented and built the first practical refrigerating machine which later led to the modern compressor systems. This was the first workable refrigeration system to be built using the vapor compression cycle.

Dr. John Gorrie (1803-1855), director of the U.S. Marine Hospital at Apalachicola, FL, designed the first commercial reciprocating refrigeration machine.


First air machine was developed.


An absorption machine was developed using water and sulfuric acid.

The first successful continuous operating heat absorption machine, using ammonia as refrigerant and water as absorbent, was built. This was the only the absorption system to gain commercial importance during the 19th and 20th century.


Dr. John Gorrie was granted U.S. Patent 8080 for building the first commercial machine in the world used for refrigeration and air conditioning. Gorrie’s machine subsequently received worldwide acclaim, recognition and acceptance.


Lord Kelvin developed the heat pump concept.


A German engineer built the first absorption type refrigeration system.


Azel Lyman of New York invents a "Method of Cooling and Ventilating Rooms" using air blown over ice in racks at a room's ceiling.


Ether was used widely as a refrigerant in the brewing and meat processing industries.


David Boyle designs the original ammonia compression refrigeration machine.


Sulfur dioxide compressor was developed.


Reciprocating compressors were developed. These compressors were used in commercial applications for ice making, fish processing, meat packing and brewing.


The use of carbon dioxide was introduced.


The first electric power plant in New York opened as an outgrowth of Thomas Edison’s research and inventions. For the first time, there is an inexpensive source of energy available to commercial and residential buildings.

Nikola Tesla and George Westinghousereceive a patent for their invention of the electric fan.


Warren Johnson invents the first automatic temperature control, leading to the formation of Johnson Electric Service Company, the predecessor to Johnson Controls.


Al Butz creates an automatic furnace value opener, the Damper Flapper, which is the forerunner of the thermostat. His company, Butz Thermo-Electric Regulator Company is a predecessor to Honeywell.


Demand for small units for home and store use developed.
A very warm winter resulted in a severe shortage of natural ice for refrigeration. Prior to this time, little artificial ice was produced, but this single event helped to start the mechanical ice-making industry.


Early 20th Century -- Before the Great Depression
1900 to 1929



Professor C.F. Marvin, US Weather Bureau devised "Psychometric Tables for Obtaining the Vapor Pressure, Relative Humidity and Temperature and the Dew Point of Air."

Warren Johnson invents the humidostat.


Alfred Wolff designs a cooling system for the New York Stock Exchange using a 300-ton cogeneration system that provided free cooling.


Dr. Willis H. Carrier (1876-1950), who is recognized as the "Father of Air Conditioning," discovers the relationship between temperature and humidity, and how to control them.

Dr. Willis H. Carrier builds the first air conditioner to combat humidity inside a printing company.


Some 70 members form the American Society of Refrigeration Engineers (ASRE) and refrigeration engineering becomes a recognized profession.

Dr. Willis H. Carrier develops the "air washer," a chamber installed with several banks of water sprays for air humidification and cleaning. Carrier's method of regulating humidity and temperature, by controlling the dew point of supply air, is still used today in many industrial applications like lithographic printing plants and textile mills.

A direct expansion cooling system is installed in a building at the St. Louis World's Fair, introducing thousands of fair visitors to comfort cooling.


Stuart W. Cramer coins the term "Air Conditioning" and uses the term in a patent claim for a humidifying head.


Willis Carrier patents his new invention calling it an "Apparatus for Treating Air."


Carrier Air Conditioning Company of American, a wholly owned subsidiary of Buffalo Forge Co., begins operation.


The first automotive heater was introduced as an accessory for the "horseless carriage." The small heater burned coal or charcoal to warm the passenger compartment continuously -- all for the paltry sum of $4.00 for this latest new gadget!

Mechanical domestic refrigeration first appears.


Willis Carrier formally presents an epoch making paper dealing with the properties of air. His assumptions are formulas formed the basis for the first psychometric chart which in turn becomes the authority for all fundamental calculations involving air conditioning.

Folies Berger Theater, New York City, installs the first air-conditioning system in a theater.


J.M. Larsen produces a manually operated household refrigeration machine.


Kelvinator produces the first automatic domestic refrigerator for the American market. 67 Kelvinator machines are sold this year. 


The domestic refrigeration industry emerges as a very important new industry.


Willis Carrier first introduces the open-type gear-driven centrifugal refrigeration machine, in which the motor is housed separately from the compressor.


Willis Carrier is acknowledged as having invented the centrifugal refrigeration machine. 

The first air conditioned movie theater opens in Los Angeles, California (Grauman's Metropolitan Theatre). Not to be outdone by LA, NYC movie houses get into the act by providing "Cooled by Frosted Air" creature comforts to their patrons at such famous movie houses such as Rivoli, Paramount, Roxy, and the Loew's Theaters on Times Square.


1923 Fast freezing to preserve food is developed.


The first hermetically sealed motor- compressor is developed by the General Electric Company for domestic refrigerators.


Carrier Corporation introduces "Weathermaker," a high-efficiency residential gas furnace incorporating a blower and filter. This was invented by Carlyle Ashley.


Automatic refrigeration units, for the comfort cooling part of air conditioning appear.

"The Electrolux," an automatic domestic refrigeration absorption unit, appears. 

The first practically applied heat pump was installed in Scotland.


General Electric introduces the "Monitor Top," the first sealed or "hermetic" automatic domestic refrigeration unit. 

Frigidaire develops and installs the first room cooler.

The first fully air conditioned office building was built in San Antonio, Texas. Named the Milan Building, it was designed by George Willis. The building's air conditioning system consisted of one centralized plant to server the lower floors and numerous other small units to serve the top office floors. 

The Chamber of the House of Representatives becomes air conditioned.


The Senate Chambers in the Capital become air conditioned. By the end of the year, the entire US Capitol is air conditioned. The conditioned air is supplied from overhead diffusers that maintain a temperature of 75 F and a relative humidity of 40% during summer, and an 80 F and 50% relative humidity during winter. The volume of supply air is controlled by a pressure regulator to prevent cold drafts in the occupied zones.


The Pre - WWII Period
1930 to 1940



The first self-contained room air conditioner is developed by General Electric. It is a console- type unit with a hermetically sealed motor- compressor (an arrangement in which the motor and compressor are encased together to reduce the leaking of refrigerant) and water cooled condenser, using sulfur dioxide as the refrigerant. Thirty units were built and sold the following year. 

The White House, the Executive Office Building and the Department of Commerce become air-conditioned.

1930-1939 Dr. Willis Carrier develops the conduit induction system for multi-room buildings, in which recirculation of space air is induced through a heating/cooling coil by a high-velocity discharge air stream. Carrier's system supplies only a limited amount of outdoor air for the occupants.

Drs. Thomas Midgley and Henne of the DuPont Company develop the fluorocarbon "Freon-12" refrigerant. This major discovery led to a new nontoxic, nonflammable refrigerant that was widely used on reciprocating and centrifugal compressors.


Freon-12 is introduced as a commercial refrigerant.

The "Atmospheric Cabinet" is developed by Carrier Engineering Company and is installed in May of this year.
1931 Lincoln automobiles are introduced with the first "modern" heaters. The Lincolns' heater housing contained finned tubes through which hot engine coolant was circulated. An electric fan blew air over the fins; volume and direction were controlled with flaps.

Columbian run on the Baltimore and Ohio railroad becomes the first air-conditioned train route.


The Thorne company introduces the first window air conditioner.


The Refrigeration Service Engineers Society (RSES) is founded and organized through the efforts of Herbert Herkimer, J.F. Nickerson and Harold T. McDermott.


Carrier introduces the hermetic centrifugal chiller, with a hermetically sealed motor- compressor assembly. 

The Ford Motor Company introduces an after market heater to "air condition your V-8"; most cars prior to this point had no heater. The new heater is installed or mounted directly to the engine exhaust manifold. Hot exhaust gases from the engine pass through flues in a small boiler-like compartment, before exiting through the exhaust pipe. Much of the heat from the exhaust is absorbed into the flue walls. The engine fan acts as a blower to force fresh air into an intake pipe and past the flue walls. This
air picks up the heat from the flue walls and delivers it to the registers via tubing run to the front and rear passenger
compartments. It only cost $14.00 and was installed "while you wait."


Frederick McKinley Jones produces an automatic refrigeration system for long-haul trucks. The system was, in turn, adapted to a variety of other common carriers, including ships and railway cars.

The first hermetic compressor for air-conditioning duty is introduced. The outer shell is bolted instead of being completely welded like present-day compressors. Motor speed is 1750 rpm versus 3600 rpm of modern units. Although the first hermetic compressor is pretty large by today's standards, the concept of passing cooling suction gas over the motor windings became universally accepted by all compressor manufacturers.


Chrysler Corporation's Airtemp Division introduces its "Store Coolers," self-contained unitary packages for commercial applications. The early models used a water-cooled condenser and were in the three to five tons capacity range. 

Albert Henne synthesized R-134A.


The capacity of centrifugal chillers increases to 700 tons.


The direct-driven hermetic centrifugal chiller is introduced by the Trane Company

Nash (automobile) offers the "Weather Eye Conditioned Air" option which was actually a fan- boosted, filtered ventilation system, not true air conditioning. Nash continues offering this option through the post WWII years.


Packard (automobile) markets the first true mechanical air conditioning system and it was controlled only by the blower switch. During the winter, the owner had to remove the belt to turn the compressor off and the cooling coils filled half of the trunk! 

Bacharach markets the first heating service instruments -- a portable gas analyzer name the "Fryite."


Practically all domestic refrigeration units were now of the hermetic type. 

Servel introduces a unit using water as refrigerant and lithium bromide as the absorbing solution. The capacities of these units ranged from 15 to 35 tons.


The War Years and Beyond



Cadillac (automobile) not to be outdone by Packard, introduces a similar air conditioning system of its own as an option. Both systems were very expensive, did not incorporate a clutched compressor, took trunk space, and had limited availability.


R.S. Gaugler develops the basic principles of the heat pipe. The heat pipe is later used in aerospace, industrial and pipeline applications. 

Pepco becomes the nation's first summer peaking utility.


Carrier introduces the first large commercial lithium bromide absorption chillers. These units were developed with 100 to 700 ton capacity, using low-pressure steam as the heat source.

There are over 6,400 Locker plants now in existence. In 1936, there was less than a million pounds of frozen food processed, but by 1945, this industry has grown to over 7,000,000 pounds of frozen food processed. Over 300 firms are now making equipment for the frozen food industry.

Refrigerant R-13 is introduced.


After World War II, the demand for room air- conditioners began to increase dramatically. Some 30,000 were produced this year. 

Prior to World War II, it was estimated that there were 30,000 refrigeration servicemen. During the war, that number was reduced to 10,000. After the war, only 25,000 refrigeration service personnel are available in the manpower pool. However, pent up delayed consumer demand requires a workforce of 50,000 refrigeration servicemen. Critical shortages result due to lack of good, qualified service personnel, which continue until to this day.

1946-1949 Texas millionaires around the Dallas/Fort Worth area begin demanding air conditioning for their Cadillacs and Lincolns. Local area shops start improvising “Hang On” units to meet the demand. They use Chieftan Compressors with no drive clutches – thus compressor speed varies with engine rpm. Condensers are mounted in front of the radiator. Blower coils are placed against the back seat cushion in front of the trunk. This heavy consumer demand drives the post war surge towards
automotive air conditioning.

1946-1953 Post World War II HVAC/R products consist mainly of applied machinery systems for large buildings,
water-cooled store conditioners, and window air-conditioners.


Annual sales of room air conditioners exceeds 100,000 units for the first time, and never drops below this level again.

Dr. Willis H. Carrier (1876-1950), regarded as the “Father of Air Conditioning” dies in October. HVAC/R industry leaders and historians alike acknowledge Dr. Carrier as having contributed more to the advancement of the industry than any other individual.

Refrigerant R-500 is introduced.

1950-1955 Heat pumps are built and marketed by companies in Southern US for local markets. However, many units are sent North to be installed in colder climates and unsuitable applications. As a result heat pumps have a high failure rate and get a very bad reputation. This dismal failure practically destroys the heat pump market – which does not recover until the 1970's.

1950-1970 Large builders like Levitt and Sons of Levittown, PA; Ryan Homes of Pittsburgh, PA, and Fox and Jacobs of Dallas, TX begin building large tract housing developments with central air conditioning as standard equipment. This major
development forces other builders and the financial community to get on the bandwagon to go to central air conditioning as a marketing tool to sell houses.


Industry introduces air-cooled operating systems instead of water cooled for condensing purposes. This major break through causes sales to skyrocket. Early systems are primarily horizontal package units for mounting in attics or on slabs at ground level. There are many advantages: no refrigerant piping, factory charged, minimum electrical, and little or no plumbing. 

Room air conditioner sales exceed one million units with demand still exceeding supply.

Air-Conditioning and Refrigeration Institute (ARI) is formed through a merger of two related trade associations. ARI is a trade association of HVAC/R manufacturing companies.


Nash automobile teams up with Kelvinator to produce the Nash-Kelvinator “Weather Eye.” This is the first true refrigerated air conditioner for the mass market. All components are installed under the hood or in the cowl area. The new A/C system is compact, easily serviceable and relatively inexpensive.


R-12 becomes the standard refrigerant in automobile air conditioners.

Other manufacturers join E.I. Dupont de Nemours and Company in manufacturing fluorocarbon refrigerants.

By now nearly a dozen companies have sprung up in Texas to meet the demand for automobile air conditioning. A popular economy model came out which is mounted under the dash and it is dubbed the “crotch cooler” by the public.


Erling Berner brings the most advanced European air curtain technology to the US from Sweden.

A new refrigerant numbering system is adopted by the HVAC/R industry: R-12, R-22, R-502, etc. to have a standard designation for all the many different trade names of refrigerant.

Ozone measurements are started at the British Antarctic base at Halley Bay. Ozone levels are found to fall dramatically in September and October to 150 DU (Dobson Units) or about half the normal level. Thus the “Ozone Hole” is actually discovered at this time, but British scientists are not cognizant of this fact for many years to come.


The first rotary compressor is introduced, permitting units to be smaller, quieter, and weigh less. The rotary is more efficient than the reciprocating compressor.

1957-1963 Industry introduces the “rooftop” combination gas heating and electric cooling unit in the 2 to 5 ton system range to be installed on the rooftops of low-rise commercial structures. This major innovation still accounts for the most dramatic growth sales rate of all packaged year- round conditioners.

1957-1973 Residential packaged unitary system sales start a dramatic growth from over 200,000 units this year to 2,767,792 by 1973.


1959 The first gas valve with a built-in pressure regulator valve that truly merited the name “combination gas control valve” is introduced by Honeywell.

The American Society of Air-Conditioning Engineers merges with the American Society of Refrigeration Engineers to form ASHRAE.


Cadillac introduces a bi-level HVAC system in their automobiles. This is the first modern automotive HVAC system which could cool the top level of the car while heating the lower level. Consequently this method provided a means of controlling in-vehicle humidity levels.


A little over 11% (756,781 units) of all cars sold in the US are equipped with air conditioning. This includes both factory installed and after market systems. 

Refrigerant R-502 is introduced.

Air conditioning plays a vital role in John Glenn's mission as the first American to orbit the earth.


York installs a three-pipe air conditioning system in the Library of Congress. Built in 1897, the building contained masonry ducts, formally used for warm air heating. York induction units are installed under windows with piping running through the ducts, resulting in a very inconspicuous installation. Chilled water is supplied from chillers totaling 17,000 tons of refrigeration, which delivers water to all capitol buildings. 


Dr. Irving Selikoff studies over 1,500 insulation workers who have been engaged in their trade for a number of years. Dr. Selikoff finds that of workers with more than 40 years work experience in the industry, more than 90% have asbestosis related medical problems. Thus a link between asbestos and cancer is first established. 

On November 9 - 10, the greatest power failure in history strikes seven northeastern states and Ontario, Canada. About 30,000,000 people are plunged into total darkness over an 80,000 square mile area. Con. Ed.'s (of NY) power grid collapses and as other utilities rush into bolster the failing grid, they are also pulled down with Con Ed. In NYC, the power failed at 5:27PM and is not fully restored for 13.5 hours. Two people die as a result of the blackout. On a brighter note, nine months later there is a surge in new births at the area's hospitals.


The total number of cars sold in the US that are equipped with air conditioners has increased to 3,546, 255 units. This represents an astounding increase of 469% over sales five years earlier.


38% of all US automotive domestic production is delivered with the air conditioner option.


Production efficiencies stall and fuel costs increase which in turn causes electricity costs to rise for the first time in years. As a result, corporations begin to seriously look at controlling overhead via reduced energy use.


Arab oil embargo causes fuel shortages and long lines at the gas pumps. Fuel prices jump up dramatically. This is passed on to the electricity user in the form of fuel escalation charge. Americans look to reduce power consumption further, and the energy debate begins. 


Variable-Air-Volume (VAV) systems begin to gain wide acceptance after the energy crisis of 1973 due to their lower energy consumption vs. constant volume systems. Today VAV systems are in common use for new high-rise office buildings in the US.


The World's largest cooling tower is completed in Uentrop, Germany. Rising some 590 feet, the cooling tower is adjacent to a nuclear plant.

York produces the first computer-controlled heat pump.

In August, 27 persons die from a mysterious legionnaire's disease after attending an American Legion convention at the Bellevue Stratford Hotel in Philadelphia. The cause of the deaths is later determined by the CDC in Atlanta to be a bacteria in the water of the hotel's cooling tower. Indoor Air Quality (IAQ) begins to be debated as a serious area of concern.


In January, bitter cold temperatures plus raging blizzard depletes the nation's supply of natural gas. 

On May 11, US Government announces ban on spray cans using "freon" to take effect in two years. The chemical is said to destroy the ozone layer.

On July 13, massive power failures plunge Westchester County and NYC into total darkness at 9:34PM. Losses from looting and vandalism are estimated at $1 billion.


In March, a reactor at the Three Mile Island plant overheats, allowing radiation to leak out through the ventilation system and into the surrounding Pennsylvania countryside. Thousands of people are evacuated while a reactor meltdown appeared imminent. 
Later, the leak is sealed without injury to anyone. The long-term damage caused by the escaped radiation is unknown.
Subsequent investigation discovers a minor technical malfunction that was made worse by human error. It is calculated that there was a one in 5,000,000,000 chance of this accident having ever occurred!
The accident at Three Mile Island signals the beginning of the curtailment of nuclear power; power shortages are predicted for the future. 

The Federal Trade Commission (FTC) introduces the "Annual Fuel Utilization Efficiency" (AFUE) rating system. The new AFUE numbers rate furnaces based upon their efficiency. The higher the rating number, the more efficient the heating system.


Demand-side management introduced as a means of lowering the demand for central power stations.


On April 26, the worst nuclear accident to date occurred at Chernobyl, a nuclear power station near Kiev in the Soviet Union. 299 people die in blast or while trying to put out the subsequent fires, but hundreds more later die or became very ill from the radiation and associated diseases. The reactor was one of the four at the site which all need a light-water coolant and a graphite moderator (not used in US reactors.)

The accident is caused by operators conducting unauthorized experiments, in which safety systems were deliberately circumvented in order to study the plant's operation. This led to the reactor rapidly overheating, resulting in the water coolant "flashing off" into steam. Hydrogen then formed as the steam reacted with the graphite, causing two major explosions and fires that are not completely put out until May 11. 

Over 200,000 people are forced to permanently leave their homes and businesses within 30km radius of the plant. Entire villages and small cities now sit as empty ghost towns, mute monuments to this disaster.

Fallout from the explosions, containing caesium-137, a radioactive isotope, affect large areas of Europe. Long term impact on life is unknown.


The United Nations Monteal Protocol for protection of the Earth's ozone layer is signed, establishing international cooperation on the phase-out of CFC's.


Talks begin to completely restructure the electric utility industry. Plans focus on deregulating operation and allowing retail competition in electricity sales.


CFC production in the US ends.


In January, all of California, Massachusetts, and portions of Rhode Island and Pennsylvania deregulate their electrical utilities. Pilot programs are underway in numerous other states. Virtually every state makes plans to restructure its electric utility industry, including Georgia.


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Thank you to Steven J. Wolfe, CM for allowing us to use his HVAC TIME LINE!
1998-2000 by Steven J. Wolfe, CM, SSAW Home Services Company, all rights reserved.