A Century of Innovation: Trane Celebrates the 100th Anniversary of the Coil

Celebrating 100 years since Reuben Trane’s revolutionary coil invention, the innovation that transformed modern heating, cooling, and the HVAC industry.

Eric Sturm

Applications Engineer

About the Author

Eric joined Trane in 2006 and is an applications engineer with expertise in acoustics, airside systems, indoor agriculture, and indoor air quality. He serves on multiple ASHRAE committees and has received the Distinguished Service Award and YEA Award of Excellence.

In 1926, Reuben Trane set out to solve a simple problem—and ended up transforming an entire industry. This year marks the 100th anniversary of the Trane Heat Cabinet, which introduced the Convector Radiator designed by Reuben Trane. The Convector Radiator was the predecessor to the modern finned-tube heat exchanger, commonly called the coil. This invention revolutionized the heat‑transfer industry by allowing consumers to replace heavy cast‑iron radiators and open fires. Today, heat exchangers shape modern life, improving both heating and air‑conditioning systems around the world. For example, building occupants enjoy consistent comfort in any climate, fresh food can travel thousands of miles without spoiling, and medicines can be safely stored and transported.

The heat cabinet was designed in the early 1920s by Reuben Trane in the corner of Trane’s first purpose-built factory (“Plant 1”) in La Crosse, Wisconsin. Legend has it that he disliked hauling heavy cast‑iron radiators up stairwells while working for his father, James Trane, as an installer. As a result, he was motivated to replace the traditional radiator. During development, he experimented with copper finned‑tube arrangements that dramatically improved heat transfer efficiency.

The exterior featured a decorative cabinet that acted as a chimney and could be finished to match the building’s décor. The coil within the cabinet operated on the principal of natural convection. Room air drifted upward through a steam or hot‑water coil and then flowed out at the top. There was no fan. A manual damper could be used to modulate airflow through the heating coil. The Heat Cabinet was significantly lighter and more efficient than the cast‑iron radiators it replaced.

To bring the invention to market, The Trane Company published a six-page advertisement in the April 17, 1926 issue of Domestic Engineering declaring the Heat Cabinet to be “…an invention so revolutionary that its far reaching effects on modern heating are beyond comprehension.” The claim sounded bold at the time, but history proved it accurate. The invention of the coil changed the heat transfer marketplace.

Reuben Trane went on to earn multiple patents for the Convector Radiator and its manufacturing processes.

Following the Heat Cabinet’s introduction, Trane’s sales grew rapidly. For the first time in its history, The Trane Company in 1926 recorded sales of one million dollars. By 1929, company sales had doubled to $2 million.

The Convector Radiator soon became the foundation for a series of new products. First, the Horizontal Propeller Unit Heater (1926) which added a fan, Trane Blast Coils (1927), and Torrivent blower-type unit heaters (1929). In 1931, Trane launched the Unit Cooler featuring a chilled water coil, a fan, and condensate drain pan. In 1932, Trane introduced the Trane Oil Burning Climate Changer which could be supplied with a new chilled water cooling coil. A version of the finned tube heat exchanger was used in Trane’s first hermetic chiller, the Turbo Vacuum Centrifugal Compressor—commonly called the Turbovac in 1938.

In recognition of this groundbreaking invention and the innovations that followed, Reuben Trane will also be inducted into the National Inventors Hall of Fame this anniversary year. Today’s Trane is a direct result of this invention—and of Reuben Trane’s remarkable tenacity.

A century later, the legacy of the Heat Cabinet and Convector Radiator lives on in every system we design. Reuben Trane’s determination to solve a practical problem sparked an innovation that reshaped modern heating and cooling—and set the foundation for Trane today. As we celebrate this milestone, we honor not only the invention itself but the spirit of curiosity and persistence that continues to drive our company forward.