Vitoflex 300-FSB – wood combustion system with flat moving grate combustion

Take advantage of these benefits

  • Three-pass flame tube boiler or two-pass boiler with water wall with flue gas temperatures below 190 °C at full load
  • Outputs: 180 to 1700 kW
  • High efficiency of up to 92 %
  • Version for flow temperatures above 110 °C available as an option
  • Minimal radiation losses due to complete insulation of the entire boiler system
  • Universal use of different types of wood fuel with moisture content of M6 to M50
  • Static firebed results in significantly lower emissions
  • Highly wear-resistant due to generously dimensioned grate area
  • Overlapping pre-tensioned grate rods ensure little fuel falls through the grate (continuous automatic ash removal)
  • Staged combustion (low NOx combustion chamber)
  • Integral backup heat exchanger for quick controllability to DIN 4751 part 2
  • Modulating load control from 25 to 100 % of rated heating output while adhering to emission levels
  • Load bearing cover on top of the boiler as part of the standard delivery – simplifies installation and maintenance and protects the thermal insulation against damage.
Vitoflex 300-FSB wood combustion system

Vitoflex 300-FSB wood combustion system

The flat moving grate is especially suitable for the combustion of wood fuels with a moisture content of up to 50 percent and an ash content of up to 3 percent. The Vitoflex 300-FSB is versatile in its use of fuel and produces flue gases with a low dust concentration due to its static fuel bed – both of which are major benefits. The geometry of the combustion chamber is the result of research at our own test facility, and flow simulation studies.

For flat moving grate combustion systems, low NOx reduction technology is generally used. The low NOx combustion chamber features primary-side air staging for reducing NOx emissions. In addition, this effect is amplified by the use of flue gas recirculation (option). Efficiencies of up to 92 percent enable maximum seasonal efficiency to be achieved in modulating operating mode

Fuel charging

Fuel is charged via a screw conveyor (screw conveyor feed) or the water-cooled feed neck (hydraulic direct feed or hydraulic feed).

Detection of fuel type

The flame temperature controller, combined with regulation of the residual oxygen content (Lambda probe), provide optimum combustion control for a wide range of fuels, whether these are damp spruce woodchips straight from the forest, pellets or very dry beech dust from a joinery shop.

Ash removal

The flat moving grate at the grate end (every other grate row is driven by a hydraulic cylinder) transports the ash into an ash container, either directly or via a screw conveyor.

Product cross-section


180 to 1,700 kW
Annual hours in use
up to 3000 hours
Chips, pieces of chipboard, pellets, residual forestry and sawmill wood, bark, chipboard, waste wood from wood processing, residual wood from thinning
Fuel moisture content
10 - 50 %
Ash content
up to 4 %
Application range
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Local and district heating associations, commercial nurseries, municipal and private property developers, recycling industry
Additional features
Low NOx combustion chamber, fully automatic ash removal, modulating load control from 25 % to 100 %, fuel supply via screw conveyors or water-cooled hydraulic feed
Produktschnitt Holzheizkessel Vitoflex 300-FSB