Ligno Holzmax

The HDG H can be combined with an oil burner if required, offering unrivalled operational reliability.

Log wood
Wood chips
Power levels: 20 kW, 25 kW, 30 kW
  • Inside view of the boiler











    1 - HDG Control
    2 - Fuel chamber
    3 - Primary and secondary air
    4 - Combustion grate
    5 - Large ash compartment
    6 - Standard flange
    7 - Cleaning turbulators
    8 - Standing rotary combustion chamber
    9 - Flue gas temperature sensor
    10 - Flue gas pipe connection
  • Technical data



    HDG H20

    HDG H25

    HDG H30

    Nominal thermal power (kW) 20 25 30
    Fuel chamber capacity (l) 165 165 165
    Fuel chamber depth (mm) 580 580 580
    Required auxiliary energy (W) 82 82 83
    Diameter of the flue gas pipe connection (mm) 150 150 150
    Flue draught requirement (Pa) 8 8 8


    Dimensions and weight


    HDG H20

    HDG H25

    HDG H30

    Height of the boiler (mm) 1540 1540 1540
    Width (mm) 910 910 910
    Depth without attachments (mm) 870 870 870
    Total weight (kg) 590 590 590


    Energy label


    HDG H20

    HDG H25

    HDG H30

    Boiler energy efficiency class A+ A+ A+
    Boiler + controller energy efficiency class (class VI) A+ A+ A+


  • 3D view

Technology makes the difference

Independent with optional oil burner

The HDG H can be extended with an oil burner. This means you can enjoy convenience and independence while continuing to use the existing oil infrastructure. Switching between log wood and oil operation is fully automatic – with many convenience programmes, such as frost protection or holiday mode.

This makes this boiler ideal for partial renovation of the heating system. There is often no need for chimney renovation in this case.

Clean and efficient

Optimum combustion and maximum efficiency due to the unique grate design and clean afterburning in the upright rotary combustion chamber.

Simple heating and cleaning

Thanks to the fuel chamber that widens conically downwards and thus facilitates the movement of the fuel, the integrated flue gas outlet and the convenient cleaning of the combustion grate by means of a sliding lever, the HDG H makes heating with log wood cleaner and more convenient than ever before.

Fully automatic on request

With convenience enhancements, such as the proven HDG automatic ignition system and the automatic cleaning system for the heat exchanger pipes, heating with the HDG H20-30 can be largely automated if desired. It can hardly be more convenient than this.

Video of the HDG H20-30

Find out how easy it is to heat with the HDG and experience the independent log wood boiler as used by our customers.

Please to watch this YouTube video.
Please to watch this YouTube video.

Absolute control

Perfectly regulated with the HDG Control

The new HDG Control is the intelligent control centre for your entire heating system. Whether on the large touchscreen on the boiler or via the app: With HDG Control, you always have absolute control over your heating system.

HDG Control Systemregler
  • Control of combustion and output
  • Control of external heat sources
  • Integration of solar thermal systems, accumulators, heating circuits, mains pumps
  • Domestic hot water preparation, etc.
  • Intelligent follow-up management: Refuel the right amount at the right time
  • "We were looking for a heating system that could run on log wood, oil and solar thermal. This flexibility was important to us. The best solution here is the H boiler from HDG!"

    Hammann family