Efficient technology

The UNIMAT UT-H hot water boiler is a shell boiler with one flame tube, built in 3-pass technology. Flue gases flow through the flame tube and smoke tubes on the inside and boiler water flows around them on the outside. The flame tube, internal water-flushed rear smoke gas reversing chamber, first smoke tube pass and second smoke tube pass are all arranged for optimum flow within the cylindrical pressure vessel. A flue gas heat exchanger can be supplemented for heat recovery from the modular kit.

Versatile applications

Important areas of use are local and district heating generation, commercial operations in all sectors of the economy, the processing industry and supply industries, as well as communal buildings. As base load, peak load and reserve heating boilers at district heating plants.


For decades our three-pass patent has formed the basis – as with the steam technology – for the outstanding and ongoing success of this series, which is still unsurpassed today. The flame tube (first pass) and two smoke tube bundles (second and third pass) are integrated with the waterflushed rear reversing chamber in the pressure vessel in an ideal way. The laterally arranged flame tube and the horizontal rear and vertical front heating gas reversal, produce an optimum radiant and convection heating surface with a large hot water chamber, and all of this within the smallest dimensions. The elastic floors are connected to the boiler jacket by the large continuous flame tube and a high number of gusset stays under even load distribution.

Benefits at a glance:

  • Intuitive boiler control on SPC basis with very hightransparency of operating data
  • High level of efficiency due to 3-pass technology, an integrated flue gas heat exchanger and effective heat insulation materials
  • Up to 93 % boiler efficiency without, up to 96 % boiler efficiency with flue gas heat exchanger and up to 105 % with condensing heat exchanger
  • 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
  • Easy for maintenance – conveniently accessible on both the flue gas side as well as the water side
  • Robust, reliable and unsurpassed in its durability
  • Acceptance in accordance with the European Pressure Equipment Directive – applied almost worldwide
  • Simple extension options thanks to integrated module technology
  • Smoke tube passes free of flow components
  • High permissible temperature spread of up to 40 K
  • 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


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