Direct-fired heaters are popular with manufacturers because they quickly warm large areas in plants, while taking up limited floor space. Similar to a gas grill, these heaters provide heat by forcing air through a natural gas flame. Their direct heat transfer is nearly 100 percent fuel and combustion efficient, and the equipment can even be equipped with cooling and energy recovery functions.
Sigma Thermal Inc. (STI) has engineered and manufactured direct-fired heaters for customers worldwide since 2007. The company also produces thermal fluid and biomass-fired energy systems, as well as indirect-process bath heaters and electric-process heaters. In 2018, STI merged with Flaretec, which designs, builds and services direct- and indirect-fired heaters.