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Keeping temps just right: the Minneapolis-developed thermostat

The Round is so ubiquitous that Honeywell was granted a trademark for the word “Round” in 1987 and for the shape in 1990.

The world’s most prolific, most iconic home thermostat was born and bred in Minneapolis.

Minnesota has temperature swings that can turn your shingles from liquid lava to cakes of ice within the span of weeks. Even our short-term temperature moods at this time of year can change from sunny and 60 degrees to 20 angry degrees within days.

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Perhaps that’s why the world’s most prolific, most iconic home thermostat was born and bred in Minneapolis. Perhaps that’s why The Round, introduced in 1953 by the company then known as Minneapolis-Honeywell, was a mainstay for a company that remained true to its course as a provider of control devices despite nearly a dozen name changes and ultimately a broad array of products.

The Round was born out of a need to find a new way to sell home temperature controls. By combining engineer Carl Kronmiller’s elegant control mechanism with industrial designer Henry Dreyfuss’ simple shape, The Round became one of the most identifiable devices in homes worldwide. The product is so ubiquitous that Honeywell was granted a trademark for the word “Round” in 1987 and for the shape in 1990. The Round was exhibited at the Smithsonian in a 1997 Henry Dreyfuss retrospective, and still remains part of the Smithsonian’s collection.

“People associate us with The Round,” said Pat Tessier, Honeywell’s director of product marketing. “It’s been almost 60 years since The Round was introduced, and it’s still popular. It’s amazing it’s had such a long life. But great products do.”

Simple beginnings

Albert Butz
Albert Butz

The first invention from the company that eventually would be called Honeywell came in 1885, when Albert Butz devised a way to control the burn rate of a home coal fire. At the time, when the house became cold, someone had to go downstairs and shovel more coal into the fire. This was inconvenient, inefficient and uneconomical. Butz devised a “damper flapper,” which was a thermostat attached to a bi-metal strip. When the temperature dropped below a certain mark, the strip closed a circuit that ran a motor, which opened a damper to outside air, thus increasing the heat without any intervention from the homeowner. When the temperature rose to a certain mark, the circuit would open and motor would close the damper.

Butz patented his invention, called the thermo-electric regulator, and in 1886 founded the Butz Thermo-Electric Regulator Company in Minneapolis. He gathered a group of investors to fund the business. The details are murky, but in 1888, Butz left for Chicago after selling his patents to the stockholders. They then changed the name of the company to the Consolidated Temperature Controlling Company and named shareholder Andrew Robbins (after whom Robbinsdale is named) president from 1889 to 1892.

A new leader: W.R. Sweatt

In 1891, W.R. Sweatt arrived in Minneapolis from Vermont. He purchased a woodenware company and, on his father’s advice, bought stock in the Consolidated Temperature Controlling Company. He ultimately bought its patents, and by 1900 owned all of the stock in what was by then named the Electric Heat Regulator Company. 

In 1908, Sweatt and factory supervisor Joel Kersteter developed a damper flapper with a modified alarm clock. This brought a patent infringement lawsuit from The Jewell Manufacturing Company of Elmira, N.Y. The matter was settled out of court when Sweatt paid Jewell $3,000 for the rights to manufacture thermostats using Jewell’s design plus $10 for each thermostat made. Several years later, Jewell was bought by Honeywell Heating Specialties of Wabash, Ind.

Growth, a merger and a name change

Sweatt relied heavily on advertising and door-to-door sales to move his product, which was emblazoned with “Electric Heat Regulator Co” in a semi-circle, and “Minneapolis, Minn” in the center. Letters to the factory were consistently addressed to “The Minneapolis Heat Regulator Company,” so in 1912, Sweatt took the hint and changed the name of the company again.  Between 1900 and 1937, the company evolved from producing one thermostat and one motor to producing more than 3,000 control devices and owning 1,000 patents. As Sweatt’s sons, H.W. and C.B., came of age, they were named directors of the company. 

Meanwhile, by the 1920s Mark Honeywell’s company was manufacturing pressurized water heating systems and was making inroads in the oil heating business, which was quickly supplanting coal as the preferred method to heat homes. Also, Honeywell still received $10 for each machine made from Jewell’s 1908 design. In 1927, The Minneapolis Heat Regulator Company merged with Honeywell Heating Specialties. The new company, The Minneapolis-Honeywell Regulator Company, would have its headquarters in Minneapolis while its oil burner business remained in Indiana. H.W. Sweatt  became president in 1934.

From clunky device to sleek art

The Round was first developed in 1941 but was shelved during World War II. After the war, the Chronotherm – a clunky, coffin-shaped regulator with an alarm-clock device – was still a hot seller for Minneapolis-Honeywell. Looking for a new product that would help sales, engineer Carl Kronmiller and industrial designer Henry Dreyfuss designed the T-86, the original Honeywell Round thermostat. The easy to make, easy to use, easy to identify home thermostat was an immediate hit with both contractors and homeowners.

Courtesy of the Minnesota Historical Society
Metal stand-up counter sign advertising the Minneapolis Honeywell Regulator Company’s Chronotherm Automatic Thermostat

Minneapolis-Honeywell offered The Round in a variety of colors to match any wall color. In 1960, a day-night version was introduced with a wind-up timer for semi-automatic night setback. In 1966, a new model was introduced that could control both heating and cooling.

Although The Round is still sold, it forms a small portion of Honeywell’s portfolio.  “We released a digital version of The Round in 2003,” Tessier said. “We also have high-tech thermostats with high definition displays, Wi-Fi thermostats that can be controlled from your smart phone, thermostats that control not just temperature but also humidity and ventilation, thermostats that are integrated into utilities’ demand-response programs, the list goes on.”

Honeywell Round Thermostats ready for final checkout and packaging
Courtesy of the Minnesota Historical Society
Honeywell Round Thermostats ready for final checkout and packaging

Even though total sales have been phenomenal, perhaps the most notable thing about The Round is that it has passed from being a utilitarian device to a piece of modern industrial art. In a 1997 Henry Dreyfuss retrospective, The Round was exhibited at the Cooper Hewitt National Design Museum, a part of the Smithsonian. 

The Round and Honeywell’s temperature-control devices were a steady force as the company navigated the 20th Century. When James Binger became chairman in 1965, he changed the name from The Minneapolis-Honeywell Regulator Company to Honeywell. Through inventions and acquisitions, Honeywell became involved in aerospace, turbochargers, computing and military weaponry as well as controls. The company later shed some of these divisions through acquisitions or mergers.

In 1999, Honeywell was sold to AlliedSignal and moved its headquarters from Minneapolis to Morristown, N.J. The new company retained the name Honeywell because of its better brand recognition — due in no small part to the enduring popularity of The Round.