The flame tube, internal water-flushed rear flue gas reversing chamber, first smoke tube and second smoke tube are all arranged for optimum flow within the cylindrical pressure vessel. In interplay with one another, the radiant and convection heating surfaces promote rapid water circulation, thereby accelerating the passage of steam bubbles to the steam chamber. The heat supplied by the fuel is converted into steam quickly and with no material stress due to an even transfer of heat. The large water chamber offers enough storage volume to be able to accommodate sudden peaks in demand.

UL-S steam boilers are mainly used in the processing industry, in the commercial sector and in public facilities.

Type UL-S UL-SX
Heat transfer medium High pressure saturated steam High-pressure superheated steam
Design Three-pass single-flame tube/smoke tube technology Three-pass single-flame tube/smoke tube technology
Capacity in kg/hour 1 250 up to 28 000 2 600 up to 28 000
Safety design overpressure (in bar) up to 30 up to 30
Max temperature in °C 235 300
Fuel Oil, gas Oil, gas


  • Intuitive boiler control on SPC basis with very high transparency of operating data
  • High level of efficiency due to three-pass technology, an integrated economizer and effective heat insulation materials
  • High level of pressure consistency and steam quality even with widely fluctuating steam demand
  • The boiler can be equipped with a separate fourth pass for waste heat use
  • The boiler body can also be used as a pure waste heat boiler behind combined heat and power plants or gas turbines
  • Automatic start-up, standby and shutdown control SUC
  • Suitable for all burner systems
  • Pollutant reduced combustion thanks to the use of highly developed firing systems and careful matching of the best boiler and burner combination
  • Simple commissioning due to pre-parameterised boiler control
  • Easy wiring on site thanks to plug-in connections