“Though much has been done by ingenious men in the art of distributing heat for household uses; it must be confessed, that in one or two instances only have they been able to make a permanent impression or bring their contrivances into that general use as to constitute them ‘machines of society.’”

This quotation, from Walter Bernan’s history of heating (published in 1845), sums up the challenge our ancestors faced. Our forebears vigorously attacked this need for heating systems that would make “a permanent impression.” It is safe to say that a continuously working team of engineers, manufacturers, merchants, contractors, and service personnel has succeeded in making heating so reliable that we don’t give it a second thought.

The story of their early work follows. This is by no means a comprehensive history — which would take at least one book, if not an encyclopedia. This article will merely highlight some important milestones and provide information not otherwise readily available. For those who wish to dig deeper, your time and your pocketbook are the only limits.

We who are associated with hvacr don’t often pause to consider the antiquity of our craft. As much as 1.5 million years ago, early humans began using campfires. The hows and whys can only be speculated upon, but we do know from archeological evidence that Homo erectus and Austra-lopithecus used fire at that time as a practical tool. At some point the campfire was brought inside caves and huts. The oldest arrangement was a central fire and a central roof opening for smoke to escape.

Later the fire was moved to different parts of a dwelling, and various schemes were tried to improve the draft of the fire by using stones. However, even the best open fire is 20% efficient, with most of the heat escaping with the smoke.

Ancient Space Heating

Early central heating seems to have developed along several lines that included hearths and fireplaces, stoves, and underfloor systems. Fixed central hearths date as far back as 2500 B.C. They were excavated in Greece.

Crude fireplace heating was used as early as the 800s A.D., and was widespread in Europe by the 13th century. Castles built at that time had fireplaces that had a short flue to the outside, a crude form of chimney. All of the early fireplaces were constructed entirely of stone, but casting technology improvements led to the introduction of cast iron firebacks designed to protect the stone from direct fire heat.

Louis Savot of France invented the raised grate and designed a circulating fireplace in the early 1600s. Savot used a hollow iron bottom and back in the hearth, through which cold room air entered at the bottom, was warmed, and entered the room through openings above the mantle.

In England, another improvement was to provide combustion air through a duct from the outside. A French priest (actually a Cardinal) wrote the first comprehensive manual on fireplace design, Mechanique du Feu, in 1713. The science of fireplace construction reached its zenith with Benjamin Thompson, Count Rumford, who published Chimney Fireplaces in 1796.

Like fireplaces, stoves also first appeared in the 800s as crude devices made from clay bricks. Masonry stoves became common in northern Europe by the 1500s. The stoves, called Russian or Swedish stoves, were very large. Later versions were very ornate, with tile coverings.

The earliest metal stoves, appearing after 1400, were made of cast iron hearth firebacks connected together. Later, cast iron sections were designed specifically for stove construction, and Holland and Germany became leading centers for iron stove manufacturing.

Phot of a ruin hypocaust underfloor heating system showing support pillars for the floor.

Ancient Radiant Heating

Underfloor heating systems, the original radiant panel systems, seem to have first appeared in the Middle East. King Arzawa installed such a system in his palace at Beycesutan, Turkey, about 1300 B.C.

The Romans brought the technology to high art, beginning about 80 B.C. with systems designed by Sergius Orata. At first the Roman systems heated only the floor, but later systems used heated walls as well, and some were designed as early warm-air heating systems, introducing heated air through floor openings.

The first systems supported the stone floor on pillars over a chamber with a fire at one end. Combustion gases passed under the floor to the other side. The hollow space below the floor was called the hypocaust, and this name was applied to all the variations of Roman heating systems where an underfloor chamber was used.

Later systems used tile flues or hollow tile walls to conduct heated combustion products to eave vents. The fire was moved outside in a separate furnace chamber. Still later, the hypocaust chamber was eliminated and replaced by floor ducts leading from the furnace to the wall flues.

Roman hypocaust heating systems were used to heat upper-class Roman houses throughout the empire, but are most noted for use as heating systems for public baths. Between 10 B.C. and 324 A.D., at least 17 major public baths were constructed using hypocaust systems.

A test conducted at the well-preserved Constantinian Baths constructed about 300 in Trier showed that these systems were very efficient. The hypocaust for the audience hall of the bath operated with a floor temperature of 77? to 95?F and wall temperatures of 66? to 90?, consuming 300 lbs/hr of wood at about 90% efficiency. The system, of course, was not automatic and not easily controlled. It took two days to preheat.

The art and science of hypocaust systems was lost after the fall of the Roman Empire. Western heating science advanced very little in the period of the Dark Ages.

Modern Beginnings: Chimneys And Stoves

The next important advance in heating was the invention of the chimney. The origins of the chimney flue probably lie with the Normans, who used sidewall flue openings in place of the previously used central roof vents. Many sidewall flues were constructed at an oblique angle upward, thus beginning a transition to vertical chimney construction.

After the 14th century, chimneys appear in written literature. However, their use seems to have spread very slowly. Chimneys were still rare enough 200 years later that one English architect, upon encountering functioning chimneys at Bolton Castle, exclaimed: “I muche notyd in the hawle of Bolton, how chimneys were conveyed by tunnells made on the syds of the walls… and by this means … is the smoke of the harthe in the hawle strangely conveyed.”

Early chimneys were very large, so as to allow a chimney sweep to climb into them. But the size precipitated such vicious drafts that room divider screens sometimes had to be used to shield the occupants.

Stove heating soon advanced beyond the crude devices first used. The first freestanding warm-air stove was probably the “Furnus Acapnos” or “smokeless stove” invented by Dalesme in France in the late 1600s. Dalesme introduced fresh fuel in the same opening as combustion air, directing all combustion products over already-burning fuel, a design that ensured complete combustion.

Although the smokeless stove was a great advance, it and other heating innovations were accepted slowly, for “…few housekeepers are philosophers enough to be willing to undertake the management of a machine requiring especial mental effort, where the advantages are not directly visible to the senses.”

The earliest stove in North America was probably a cast iron box stove invented by Dr. John Clarke of the Massachusetts Bay Colony about 1652. This type of stove had originated in Holland and was imported into England after 1600. By the mid-1700s, cast iron box stoves were being manufactured by a number of eastern Colonial American foundries.

Stoves continued evolving throughout the 1800s. Notable improvements included the base burner stove invented by Eliphalet Knott in 1833, and the airtight stove invented by Isaac Orr in 1836.

A stove with thermostatic draft control was invented by F.P. Oliver in 1849.

By the time of the Civil War, cast iron stove manufacturing was a large and well-established industry, particularly in the northeastern U.S. By 1900, thousands of different designs (many approaching pieces of art in their appearance) were produced by dozens of manufacturers.

Heating With Warm Air

Warm-air heating as we know it may date to around the year 200, when Emperor Heliogabalus is said to have had a palace warmed by air. A stove was placed in a brick chamber under the rooms. Outside air was ducted into the chamber under the stove, the heated air then flowing through openings into the rooms above.

The first good records of a warm-air system date to the 1200s. These records indicate that the city hall in Luneberg, Germany had a central warm-air system using three furnaces. The heating chamber connected to the rooms above with round ducts that opened under seats. Temperature was individually regulated with iron covers over the duct openings. A similar system was constructed about the same time at Marburg Castle in Germany.

The Industrial Revolution provided the catalyst for more advanced warm-air systems. In England about 1805, William Strutt invented a warm-air furnace that consisted of a riveted, wrought iron air chamber encased in brick. A couple inches of space between the brick and the iron allowed air to circulate. A large space outside the brick was split horizontally into two sections, the lower one for cool air and the upper one for heated air. A multitude of 2-sq-in. openings penetrated the brick casing. Cool air moved from the lower chamber through the openings, was heated by the iron furnace, and moved out through the upper openings into the heated air chamber.

Ducts fed the heated air into rooms, and the room openings were fitted with dampers “to regulate the admission of warm air at pleasure.” Strutt’s hot air furnaces were referred to as “cockle,” “Belper,” or “Derby” stoves.

At about the same time, firetube hot air furnaces were invented in France. These “caloriferes” were constructed with a number of iron pipes placed at a slight pitch through the brick faces of a fire chamber. The cool air entered at one face, was heated in the pipes exposed directly to the fire, and exited at the other face.

Technically, the cockle and calorifere furnaces were important advances, but their constructors knew very little more about the true principles of hot air heating than did their ancient predecessors.

A more scientific approach emerged when Professor Dr. Paul Meissner of the Vienna Polytechnical Institute, Vienna, Austria, published a book on heating with hot air in 1821, wherein he explained the laws of warm-air heating. He was the first to recognize that provisions must be made to draw off cool air as warm air is admitted to a room; that this cool air could be returned to the furnace for reheating; and he even proposed the use of mixing dampers.

Meissner was vociferously attacked by stove makers of the time. He replied with words that ring true today: “As an invention enters more deeply into our daily life and has greater value for the general welfare, and the more simple the principles upon which it is based, so much greater in proportion is the opposition to it, for at the very beginning it is bound to cross certain private interests of such parties as are living by their wits, and insults the pride and selfishness of others that are non-producers, both of whom are consumed by jealousy and short sightedness, because something useful has developed in the brain of a third party. Both the opposition parties, though they hate each other, will combine to cry down the invention and crush the inventor.”

Meissner believed that not only would they beat a path to your door if you invented a better mousetrap, they would also knock your door in and proceed to beat you up!

Despite the contemporary opposition, Professor Meissner was right, and his principles underlie all modern warm-air heating systems.

In the United States, Oliver Evans published The Young Millwright And Miller’s Guide in 1795, in which he illustrated a central hot-air system with ducts leading to individual rooms.

Other hot-air systems were introduced in the United States before 1820 for use in larger institutional buildings. The first U.S. building to be centrally heated was probably the Massachusetts Medical College in 1816. The system used a gravity hot-air system with a basement furnace and ductwork to the rooms.

A central heating furnace, of the gravity type later commonly seen, was said to have been invented in 1835 in Worcester, MA. Early furnaces were locally produced for the specific job — there was no furnace industry per se. The first U.S. furnace manufacturer was the Richardson & Boynton Co., which began mass marketing furnaces about 1837. The company survived until 1942.

There were several manufacturers by the time of the Civil War, but the golden age for warm-air furnaces was after that war. From 1866 to 1900, many dozens of firms entered the furnace business. Furnaces were considered to be safe and easy to operate, ensuring their early popularity over steam heating systems, which required skilled operation lest they would explode!

Early furnaces were rated by fire pot size and/or by the volume of building air they would heat. There was no standard for rating, and identical furnaces sported different ratings by different manufacturers. Outlandish claims were made, and by 1900 many manufacturers had gone out of business or merged due to a raging price war. The price war had resulted in wilder claims for the cheapened products, and by the turn of the century, warm-air heating had gotten a bad reputation as a “don’t give a hoot” industry.

Hot water heating was making inroads into what had been a seemingly secure market. Frightened manufacturers formed the Federal Furnace League in 1905, to “elevate warm-air heating to the position it rightfully deserved.” For the first time, an attempt was made to standardize ratings among manufacturers. These efforts culminated in the National Warm Air Heating and Ventilating Association in 1914. Test and research programs were conducted at the University of Illinois. The association later produced a series of manuals for proper sizing and installation of warm-air heating systems.

Warm-air systems relied upon the temperature/density relationship to induce circulation, but the idea of using an electric fan to boost circulation surfaced shortly after table fans became widely available in the 1880s. One installation was reported in a house in the late 1800s where a fan was combined with a homemade gas furnace in Mannington, WV. It seems that a school board member wanted to duplicate the large fan system at his school, so he downsized the idea for his home.

General Electric advertised such a booster fan designed specifically for furnace application in 1910. A paper was presented to the American Society of Ventilating Engineers in 1896 discussing the use of blowers with furnaces. Emerson Electric marketed a disc fan blower to be added to the return side of the furnace in 1908. Blowers or disc fans were periodically applied to residential furnaces into the 20s, after which manufacturers began to take a hard look at equipping furnaces with fans as a package. However, package blower-furnace units were not widely available until the 1930s.

Steam Heating

William Cook was apparently the first to propose steam heating in 1745 in England. By the 1790s, steam engine pioneers Matthew Boulton and James Watt had installed steam heating in their residences. Watt tried a crude radiator made of soldered copper sheeting.

At first steam heating progressed only in England, being used to heat mills and factories. In fact, the first manual on steam heating was titled An Essay on the Warming of Mills and Other Buildings by Steam, published in Glasgow, Scotland by civil engineer Robertson Buchanan. The advantage of steam heating, according to Buchanan, is the avoidance of “the excessive expense of insurance, arising from the combustible nature of the materials of cotton manufacture in particular; the great difficulty of retrieving the injury resulting to a well-established business from the accidental destruction of machinery; and the frequent alarms from fire in our powder mills, arsenals, and dock-yards....”

Buchanan expanded his manual to a full handbook on steam heating in 1810. His Treatise on the Economy of Fuel and the Management of Heat was the first heating engineering book.

Europeans seem to have been reluctant to use steam heating, in some cases for political reasons. In Germany, architect Ludwig Catel published a manual on steam heating in 1817, “to help others to avoid spending good money to have steam heating apparatus carried out by the English.” A few installations were made, but steam was generally not accepted in Europe for another decade or more.

There was no such resistance to steam in the U.S. due to the ready import of ideas and equipment from England. A number of steam heating systems were installed after 1810, one of the earliest at a factory in Middletown, CT, in 1811. This system used exhaust steam from a high-pressure steam engine; thus the heating was essentially free. Joseph Nason and James Walworth installed steam systems after 1840 using small-diameter wrought iron pipe. Nason and Walworth installed numerous steam heating systems in large buildings during the next decades, including the White House and the Capitol Building in Washington, DC.

One of the earliest pioneers in residential steam heating systems was Stephen Gold, a Connecticut stove maker who began experimenting with steam in the late 1840s. The steam systems of the time were considered too complicated and unsafe for household use. On the other hand, furnaces and stoves were considered uncomplicated and safe, but many people were uncomfortable in buildings heated by air due to “scorched air” and excessively dry conditions. Gold strove to overcome these issues, and was granted a U.S. patent for “Improvement in warming houses by steam” in 1854.

Gold’s system was unique at the time. Large steam systems used coils or rows of pipe to heat rooms, while Gold used the first radiator, a device consisting of two dimpled iron sheets that were riveted together at the dimples. The edges were rolled over with a piece of cord as a gasket. Gold’s radiator came to be called “the mattress radiator” due to its appearance, and was manufactured for at least 50 years.

Gold’s boiler was made of wrought iron and featured an automatic draft regulator and automatic water valve. The system operated at very low pressure using one pipe to distribute the steam. Gold’s radiators featured inlet valves and manual air vents. The system was manufactured by the Connecticut Steam Heating Company after 1854.

Steam heating, like warm air, blossomed after the Civil War. A number of manufacturers began making boilers and radiators of various designs. Like stoves of the era, many could be considered works of art. The steam heating systems of the 19th century operated at low pressure, using one or two pipes and a boiler or steam engine exhaust for a steam source.

As buildings in the U.S. became larger and more intricate, the earlier steam systems proved to have problems with effective distribution of the steam and condensed steam (condensate). These problems were overcome in the 1890s with the development of the vacuum-return steam heating system, perfected by Warren Webster using the patents of DeBeaumont and Williames. The Webster system maintained a vacuum in the condensate return line, thus drawing steam throughout the system no matter the size. Vacuum-return systems soon became the system of choice for larger buildings.

Many different patented designs of steam heating systems were in use by World War I. However, steam heating never really became popular for home heating due to perceptions about complexity, noise, and fear of explosions. The choice for “wet” heating systems in residences and small commercial buildings fell to hot water, later named “hydronic” systems.

Hydronic Systems

The earliest recorded use of hot water heating may be that of a monastery in Greenland that used hot spring water to heat the buildings at the end of the 14th century. In England, Sir Hugh Platt proposed using hot water to dry out gunpowder in 1653, and Sir Martin Triewald proposed warming greenhouses with hot water.

In the late 1700s, M. Bonne-main in France constructed an actual hot water heating system using a boiler. The French idea was refined and introduced into England by the Marquis de Chabannes in 1816. Charles Hood of London wrote the first engineering handbook for hot water heating in 1837, which was subsequently published in revised editions for 50 years.

All of these early hot water systems relied on the thermosiphon principle for circulation and came to be called “gravity” systems. Some attempts were made to accelerate the circulation with crude pumps, but the idea of using a circulator did not see real use until the beginning of the 20th century.

Early hot water systems used very large pipes because it was thought this was necessary to ensure adequate circulation and heat retention. Angier Perkins recognized the drawbacks of these bulky systems. He designed a high-pressure hot water system using small-diameter, thick-walled wrought iron pipe that he patented in 1831. His system heated the water in pipe coils placed in a furnace, then circulated hot water to coils of pipe or baseboard heaters in the rooms to be heated.

Perkins relied on very high temperatures and pressures to force the water to circulate through 1-in. pipes. The pipes were connected with screw joints to withstand the high pressures. Perkins’ systems were designed to operate at a 400? temperature and about 200-psi pressure. They frequently ran hotter than that — as much as 550? and 1,100 psi. After a few fires and explosions, Perkins modified his system by installing a temperature-limiting device, operating the system at a lower pressure and temperature. The Perkins’ system was very popular in England until the 1850s but then died out. The idea of high-temperature hot water systems languished until they were revived in the 1920s.

In the U.S., Robert Briggs began to design and install hot water heating systems after 1840.

The aforementioned Joseph Nason and James Walworth introduced the Perkins’ high-pressure hot water heating system into the U.S. in 1842; however, it was little used. Use of hot water systems seems to have been limited until the 1880s, when they suddenly became very popular.

Steam heating for residences, already crippled by competition from furnace manufacturers, rapidly declined, and hot water became the dominant system for homes, especially in the eastern United States.

Registers, Boilers, Radiators, And Industry Consolidation

No sooner did furnace manufacturers establish themselves, then makers of stock designs of heating registers appeared as well. Tuttle & Brother was established in Brooklyn in 1845 to manufacture heating registers and grilles. The name changed to Tuttle & Bailey (T&B) in 1848. William Highton & Sons began in Providence, RI, in 1850 — the company was later absorbed by Hart & Cooley in 1928.

An 1851, the T&B catalog lists cast iron registers available with black or white “japanned” finish, gold bronze, or with nickel plating. They were shipped in wooden barrels packed in straw. Packing was expensive, and it was customary to charge the customer for the packing as well as the register.

In 1895, Charles Foster of St. Louis, MO, patented a damper-type register. In 1899, Novelty Manufacturing Co. was the first to make steel registers in Jackson, MI.

The design and artistry of heating registers was almost limitless. Some had footrests, humidifying pans, or were even designed to look like fireplace fronts.

Meanwhile, boiler design saw continuous improvement. Section-al cast iron boilers appeared around 1850. John Mills invented a successful watertube boiler in the 1870s. Early boilers (and furnaces) were encased in brick, but by 1900, steel-encased furnaces and free-standing cast iron boilers appeared.

Early steam and hot water systems used pipe coils mounted on walls or in various places in a room. Often these pipes were coiled or assembled in a serpentine manner, and were placed in ornate cabinets called “coil cases.” Placement of the heating surface in the room came to be called “direct” radiation.

The coils were also recessed in walls, behind grates, or placed below the floor in a compartment connected to the room with a short duct and register. Such an approach was referred to as “indirect” radiation. Radiators of all types were sized by the amount of surface they had, measured in square feet.

Radiators as we know them date to 1863, when Joseph Nason and Robert Briggs patented a new design featuring vertical wrought iron tubes screwed into a cast iron base. Each tube was proportioned to have exactly 1 sq ft of surface when screwed into the base, allowing many standard sizes of radiators to be manufactured. Nelson Bundy invented the first popular cast iron radiator in 1874. By the 1880s, cast iron sectional radiators became very popular.

Competition between manufacturers of boilers and radiators was intense. As in the furnace business, bankruptcies and consolidations were frequent. The late 19th century saw the rise of the Business Trust, and the heating industry was quick to use this business form to improve the competitive situation. The most successful such trust was the American Radiator Company, which consolidated a number of the leading boiler and radiator manufacturers in 1891. Its advertising boasted: “The largest makers of radiators in the world.”

The company was the Microsoft of its time. Its success in capturing most of the radiator business is evident when surveying buildings with old radiators — American Radiator made most of them. The company exists today as American Standard.

The Fan System

Concurrent with the development of static steam, hot water, and warm-air systems, another line of thought proceeded, that of using forced hot air.

All of the early developments in forced-air systems concerned themselves with large buildings and factories. These large combinations of a fan and heater were referred to as “plenum” or “hot blast” systems. They rarely used furnaces directly in the airstream, but instead relied on indirect heaters using steam and, in a few cases, hot water. All of the early systems used 100% outside air. The use of recirculated air was not considered until after the 1890s.

John Desaguliers had designed the first modern heating blower, turned by hand by an operator referred to as the “ventilator” for the British Houses of Parliament in 1735. The design of centrifugal blowers was continually improved in England and Europe during the late 18th and 19th centuries. These early fans were mostly operated by steam engines.

The Marquis de Chabannes advocated use of a centrifugal fan to force heated or cooled air through ducts to rooms. In December of 1815, he obtained a British patent for “a method or methods of conducting air, and regulating the temperature in houses or other buildings, and warming and cooling either air or liquids in a much more expeditious and consequently less expensive manner than hath hitherto been done....”

Walworth and Nason installed the first U.S. fan-type system for the U.S. Customs House in Boston in 1846. “The fan used was a paddle-wheel like that used on steamboats....The air was heated by coils of 3/4-inch pipe...a sufficient pressure being carried on the boiler to run the small steam engine that drove the fan, the exhaust steam being used to heat one of the coils.”

General Montgomery Meigs planned a much larger system in 1855 for the House and Senate wings of the U.S. Capitol. “The system recommended and adopted was that of a forced or plenum ventilation, the entering air being propelled by two large centrifugal fans, one 16 feet and one 12 feet in diameter, motive power being applied by vertical (steam) engines, the cranks of which were keyed on to the fan shaft. These fans as built...consisted of circular iron discs...on the periphery on one side of which was bolted cast iron quadrilateral vanes. These vanes were curved and placed on the line of a logarithmic spiral of 45 degrees. The fans were centered in a ring of brick work....”

The earliest fan systems were constructed completely onsite. However, it was soon evident that there was a manufacturing opportunity. Shoemaker Benjamin F. Sturtevant patented a combination fan and heat exchanger for cooling or heating purposes in 1869. He soon had established a company to manufacture and sell fans and heating systems. Other companies, such as Buffalo Forge Co. and American Blower Co., followed.

By the 1890s, the method of using a fan to blow air over a steam- or water-heated surface, then distributing the air to rooms in large buildings, was well established. Such “hot blast” systems easily combined the need for ventilation with heating. By the turn of the century, these systems were quite sophisticated, some even featuring thermostatic and zone control. The plenum system lent itself to cooling as well with additional coils cooled in summer by refrigerated brine. These hot blast systems were also being equipped with air washers for filtering and humidifying by the 1890s.

The popularity of hot blast systems spurred the radiator manufacturers to develop cast iron heat exchangers with an extended surface that could replace the banks of pipe that previously had been used. The most successful was the Vento sectional cast iron surface developed by John Spear in 1903 and marketed and manufactured by American Radiator Co.

Lawrence Soule, who worked with Spear, improved upon the idea with his “Aerofin” heating surface, introduced in the early 1920s. The Aerofin used spirally wrapped copper sheet to produce a finned, lightweight heat exchanger. It quickly supplanted cast iron.


Widespread use of comfort heating systems of various types in the latter 19th century provided the impetus to develop effective means to control the systems according to demand. There were sporadic attempts prior to this, but most centered on a direct control of the fire draft.

These schemes were often complicated to adjust, if they could be adjusted at all. They were inconvenient, since one had to go to where the heating unit was located. Most heating systems simply relied upon the building engineer or homeowner to manually adjust firing rates, draft, valves, or dampers.

Modern thermostat control suddenly appeared from several inventors, all about the same time. Andrew Ure in England invented the bimetal thermostat. He received a British patent in 1830, but his device saw little use. In the U.S., the rapid development and use of central heating spurred several individuals to invent thermostatic control methods in the late 1800s.

Professor Warren Johnson taught at a school in Wisconsin, where the only means of room temperature control was to tell the janitor to go to the basement and adjust steam valves. Johnson developed an electric annunciator system in 1873 that was used to signal the janitor when heat needed adjusting. He continued experimenting and in 1885, patented a thermostat that relied on compressed air to operate steam valves. He then established the Johnson Electric Service Co. to manufacture and install his system. Johnson went on to invent the humidostat for control of the humidity in buildings in 1905.

The firm continues today as Johnson Controls.

Albert Butz, partner in the Mendenhall Hand Grenade Fire Extinguisher Co. (hand grenade fire extinguishers were thin glass containers of carbon tetrachloride, designed to burst when thrown into a fire — the carbon tet acted like today’s halons in smothering the fire) patented a thermostat-controlled draft damper in 1886. Butz’s thermostat was electric, using battery voltage to activate a spring-loaded motor that operated the draft damper in the boiler or furnace.

The Butz Thermoelectric Regulator Company of Minne-apolis, MN, began manufacturing and selling the invention; however, the product did not sell well to homeowners. The company went through several name changes, ultimately ending up as the Minneapolis Heat Regulator Co. After WW I, the company emphasized oil burner controls and in 1927 merged with the Honeywell Heating Specialties Co. to form the Minneapolis-Honeywell Reg-ulator Co., known today as Honeywell Inc.

About 1887, William Powers was daydreaming during a dull Sunday sermon when the idea occurred to him that vapor pressure could be used to manipulate a draft damper in a furnace. He formed the Powers Regulator Co. in 1890 in Chicago, IL, to experiment and develop thermostatic controls. (Ironically, the first installation was in a church, where a thermostat was used to control mixing dampers in a plenum heating system.)

The first Powers thermostats were about 15-in. dia and made of solid brass with ornate detail. Powers concentrated his efforts on large heating systems, and his system was used in many notable buildings, including the Chrysler and Empire State buildings.

The Powers line of automatic control is now part of Siemens Building Technologies.

Automatic Heating

Before WW I, most homeowners had hand-fired coal furnaces. They had to descend into a basement and contend with coal shoveling, ash clearance, and a method of temperature control that was no more than “by guess or by gosh.”

Although thermostat-controlled draft regulators had been available for several decades, they were little used in homes.

Automatic firing of heating equipment was hampered by lack of widespread availability of electric power and reliable electric motors. Once the motors were available, inventors had to figure out how to apply them to the firing of heating systems. They also had to develop controls that would permit thermostats to directly control the equipment.

These efforts began after 1900, accelerating through the next two decades. During WW I, a coal shortage and a government initiative to conserve energy gave a push to automatic system development.

Homeowners were used to banking coal fires at night, waking up early to stoke the fire with fresh coal, then waiting for bulky heating systems to respond. Guesswork and experience dictated how much coal to use, but this was obviously wasteful. The first electric coal stoker that could be controlled by thermostat was placed on the market in 1912, and by the 1920s, automatic coal systems were available from many manufacturers.

Night setback thermostats saw renewed interest. One using a wind-up clock had been brought out by Jewell Thermostat Co. in 1905. Sales of these devices surged during the war.

“Coal-less Mondays” were introduced in 1917, stimulating the use of oil and gas. Milton Fessler invented a residential oil burner in California between 1905 and 1908. Before the war, there were several manufacturers of domestic oil burners; Underwriters Laborator-ies certified an oil burner in 1912.

The first oil burner with high-voltage electric ignition, called the “Electrol,” was introduced in 1918. By the mid-20s, the market for domestic oil burners skyrocketed. In 1924, the first controls designed exclusively for oil burners were marketed by Honeywell.

Gas heating advanced as well. Frederic Albert Winslow was ridiculed in London in 1805 when he proposed that gas could be used for heating as well as lighting, and it was not until about 1840 that gas heating was attempted in the U.S. Sporadic attempts were made, especially in the western states, but there was no real incentive to push the use of gas until the gas utility companies saw their revenues decline as electric lighting advanced after 1880.

Casting about for a way to increase gas use, they began to investigate the use of gas for heating. Ohio Gas Light Co. in 1891 installed gas heating systems in 50 homes as an experiment. After 1900, some furnace and boiler manufacturers added gas-fired equipment to their lines, but gas equipment didn’t really take off until the war. By that time electric gas valves had been developed, so the heating system could be readily controlled by thermostat. The need for uniform testing resulted in the establishment of the A.G.A. Testing Laboratory in Cleveland, OH, by the American Gas Assoc-iation in 1925.

Use of natural gas was limited at first because of condensation problems in flues. The phenomenon was reported in trade literature as early as 1901, and condensation was apparently common enough that after a number of gas installations were placed in Buffalo, NY, it was reported that “almost every person has an iron pipe put into his chimney to carry off the water.” By the 1920s, the design application of gas-fired equipment was better understood.

Ornate cast iron stove made in the eastern United States about 1840.

Modern Heating For A Modern World

By the mid-1920s, heating could be said to have advanced to a pure form of democracy: Everyone could participate. Heating devices and systems had become relatively inexpensive and almost completely reliable. Their efficiency had been improved.

One could avoid the basement for weeks at a time and safe, effective heat was only as far away as the nearest thermostat. The state of heating would advance at an even more astounding pace, such that our predecessors would stare in wonder at what has been accomplished.

By 1926, the date The Electric Refrigeration News began publishing, heating had advanced from the campfire to something so silent, automatic, and reliable that we simply take it for granted — we just “turn on the heat.” Our industry has succeeded in transforming heating apparatus into Walter Bernan’s “machines of society.”

We who design, manufacture, market, install, and service heating systems inherit a legacy that serves one of the most important necessities of society. This review of our proud past can only inspire us to keep up the good work!

Nagengast is a consulting engineer from Sidney, OH, who has researched the history of hvacr for 30 years. He is past chairman of the ASHRAE Historical Committee and coauthor of Heat & Cold: Mastering the Great Indoors, a Selective History of Heating, Ventilation, Refrigeration and Air Conditioning, published by ASHRAE for its centennial in 1995.

Publication date: 11/12/2001