The 1920s: Ushering In The Modern Age Of Heating

November 5, 2001
The 1920s are known as “The Roaring Twenties” and “The Jazz Age.” Another fitting moniker for the 1920s could be “The Home Appliance Decade.” Central heating and kitchen equipment were improving, and the decade saw them finding their way into more and more homes.

Historically, the same equipment had been used for both providing warmth for a dwelling and to cook food. In the 1800s, there were such things called heating stoves that warmed a room. By the 1920s, homes generally had one appliance for heating and another for cooking. The old connection between stoves used for heating and those used for cooking can be seen in the fact that Scientific American Home-Owners Hand-book from 1924 refers to a furnace as a stove.

Old King Coal

Whereas the kitchen stove of the 1920s was more likely to be fueled by either gas or electricity, coal was the fuel most often used for furnaces. There are problems associated with using coal to heat, especially in houses. One problem is the backbreaking and seemingly neverending work of shoveling it in the furnace to keep the fire going. Another problem is that it is hard to keep coal dust from spreading throughout the house.

An invention that made heating with coal easier was the automatic stoker. While automatic stokers first appeared in industrial applications early in the century, they were not introduced into homes until the mid-1920s. The stoker sat next to the furnace. Connecting the two was a conveyor belt that moved coal from the stoker to the furnace as needed.

Despite these problems, coal was king in heating American homes and businesses. Evidence of this can be seen in popular culture, such as this excerpt from a song recorded in 1935 about a coal man, “The Hottest Stuff In Town.”

Now mama, papa’s just a little ol’ coal man,

Sellin’ the hottest stuff in town.

Now, baby, I’m just a coal man,

In the winter, I’m good to have around.

I’ll take your order and fill your bin,

Go get it cleaned out and I’ll put it right in,

’Cause I’m just a coal man,

Selling the hottest stuff in town!

Figure 1. David Crosthwait Jr. invented this "Method and apparatus for setting thermostats." He received the patent (#1,661,323) for it on March 6, 1928. The assognor is C.A. Dunham (Marshalltown, IA). (U.S. Patent and Trademark office.)


Coal was by no means the only fuel choice, however. Coal was needed by the military during World War I, so there was a shortage of coal for civilian use. On the other hand, there was no shortage of oil, which made it beneficial for heating.

For those furnaces that didn’t use coal, a new design of furnace with a more efficient oil-gas burner came on the market. Those units had a smaller footprint than coal furnaces, which were known as “the monster in the basement.” One of the early automatically controlled residential oil burners was the “Nokol” oil burner using the Doble-Detroit System. An abundance of other oil burner models came out in the 1920s.

Honeywell’s oil burner controls in 1917 were composed of a damper flapper connecting to the start-stop component that was linked to a thermostat. The company’s oil burner relay debuted in 1923.

Oil heating spread. By later in the decade, it is estimated that 400,000 houses in the United States were heated with this fuel.

Natural gas and oil had a couple of obvious advantages over coal; neither gas nor oil needed to be stoked to keep the furnace going, and neither is as messy as coal.

Natural gas had other benefits. It did not have to be delivered, as both oil and coal did, and it has a higher heat value than most other kinds of gas. In 1927, 250,000 U.S. homeowners switched over to heating with natural gas, which brought the total of residential customers up to almost 4 million. Manufactured gas (gas made from coal, petroleum, waste fats and oils, or gasoline) was even more popular than natural gas; 12 million residential, commercial, and industrial customers used manufactured gas.

By the late 1920s, approximately 66% of homes had electricity. General Electric, the successor of the company Edison formed (the Edison Electric Light Company), offered numerous products for electric cooking, as well as heating equipment.

Though electricity was not used much to heat homes in the 1920s, it was used to run thermostats, and its accessibility made it ripe to compete in the fuel battle that would take place in the decades to follow.


The invention and application of room thermostats made possible the development of the automatic central heating system. By 1927, thermostats were used to control heating units.

Another heating innovation during the early 1920s was the aerofan, or the blower. The advent of the blower made modern forced-air furnaces feasible. This offered an alternative to the room radiator, which warms and moves air around a room via convection currents.

Peerless Unit Ventilation Co. combined the “Vento” steam radiator, made by the American Radiator Company, with a unit ventilator in 1923. This and other similar units were widely installed in classrooms and drugstores, thus becoming known as “classroom units” or “drugstore units.”

Aerofin Corporation introduced fintube systems in 1922. They were constructed of seamless copper or brass. Making radiation surfaces out of sheet metal and combining them with copper tubing to make fintube designs was debuted by a variety of companies. The Trane Heat Cabinet, announced publicly in May 1926, was composed of a U-shaped copper tube and fin design in a sheet metal enclosure.

To decrease heat loss, pipes were wrapped in insulation. The type of insulation used in the 20s was asbestos sheets. It wasn’t until decades later that the dangers of asbestos became known, and asbestos had to be removed from homes, schools, and other buildings.


A.C. Willard and A.P. Kratz, heating engineers, realized that dumping heating into a room wasn’t a good idea. Rather, an aim in heating should be to have the floor, the “living zone” (approximately waist high), and the “breathing zone” (approximately head level) of the room at the same temperature. In other words, their goal was to have a zero gradient between the sections. Differences in temperatures between these zones is something that influences how comfortable a person is in a building.

With early room radiators, convection currents were at work. Later improvements — radiator covers, shields, and enclosures — were designed to direct rising convection currents into the room, and these did improve room gradients. In addition, they decreased the direct radiant heat lost through the wall at the back part of the radiator. Another form of radiator was a wall-mounted unit with a thinner profile that headed convection currents upward, without the hot air greatly stratifying. It was mostly used in commercial buildings and locker rooms.

The 1920s was a time of great growth for the heating industry. The various forms of energy used for heating equipment spurred development of some components, and at least a few of these items are a fundamental part of the hvacr industry today.

Publication date: 11/12/2001