Founded in the United States in 1917 by Pittsburgh engineer Edwin L. Wiegand, Chromalox designs and manufactures electric thermal technologies and industrial heating systems. Its long history runs from the strip heater that helped become the modern electric clothes iron to heaters used in nuclear plants, NASA launch systems, and the Apollo 11 lunar module. Now part of Spirax Group, Chromalox develops thermal solutions for demanding industrial applications while supporting the shift toward lower-carbon operations.
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Watlow Electric Manufacturing CompanyWatlow Electric Manufacturing Company is a St. Louis-founded industrial manufacturer that designs and makes complete thermal systems, including electric heaters, temperature sensors and control equipment. Founded by Louis Desloge Sr. in 1922 to produce heating elements for the shoe industry, Watlow now employs more than 4,200 people across 12 manufacturing facilities and five technology and development centers. The company holds more than 1,100 patents and brings a century of thermal engineering experience to demanding industrial applications worldwide.LOUIS, MO
HeatrexEstablished in 1959, St. Louis-based Heatrex designs and manufactures engineered electric heating and thermal-management equipment for commercial, industrial, OEM, and rail applications. Its work ranges from custom heating systems to components such as tubular elements and immersion heaters, with concept development, prototype testing, and production handled across two Missouri manufacturing facilities. Heatrex is part of ASPEQ Heating Group and serves customers in North America and abroad.MEADVILLE, PA
Micropyretics Heaters International Inc. (MHI Inc.)Founded in Cincinnati in 1991, Micropyretics Heaters International Inc. manufactures patented electric thermal equipment and materials for energy-efficient industrial heating and decarbonization. Its work spans compact process-gas heaters and high-temperature steam generators, alongside specialized heating materials and controls, serving more than 1,300 customers and exporting to over 25 countries. MHI’s vertically integrated operation has developed its own electronics, refractories, software, and components since the mid-1990s.CINCINNATI, OH
Selas Heat Technology CompanyFounded in 1896, Selas Heat Technology Company is a combustion-industry pioneer whose history stretches from gas lamps to industrial heat technology. Today, the Streetsboro manufacturer serves thermal-processing operations with industrial gas burners and combustion systems, supported by engineering expertise developed over more than a century.STREETSBORO, OH