Three-Pass Helical Coil Heaters
Three-Pass Helical Coil Heaters provide higher outputs than two-pass heaters of the same physical size. By elongating the path of burner gases to the exhaust, the three-pass design performs at high thermal efficiency.
Three-pass heaters utilize two helical coils: a smaller inner helical coil fits inside a larger outer helical coil. The burner fires down the center of the inner coil, creating the first pass of hot burner gases. This pass exposes the inner coil to both radiant and convective heat.
At the end of the coil, the burner gases turn and pass through the space between the two coils, creating the second pass. This exposes both coils to convective heat.
At the end of the second pass, the hot burner gases turn and pass along the outer surface of the outer coil, creating the third pass and exposing the outer surface of the outer coil to convective heat.
Heat transfer oil flowing through the two coils, either sequentially or in tandem, gains heat from the hot coils. Many options are available. All heaters can be customized to meet your specific needs.