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100%-H2-ready: Viessmann gas condensing boilers manufactured from 2024 can be converted to pure hydrogen operation

Gas condensing boilers from the Vitodens 300 and 200 series manufactured by Viessmann from 2024 will be 100% H2-ready. They can be operated with pure hydrogen after a conversion. Corresponding conversion kits should be available from the beginning of 2026. Converting the units is simple and the procedure is similar to normal maintenance.

Future-proof heating with 100% H2-ready appliances from Viessmann
  • Manufacturer’s declaration for units in the Vitodens 300 and 200 series
  • Conversion kits should be available starting at the beginning of 2026
  • Converting the units is simple – the procedure is similar to normal maintenance

Allendorf (Eder), 12/11/2023  – Gas condensing boilers from the Vitodens 300 and Vitodens 200 series manufactured from January 2024 can be converted to run on pure hydrogen in the future according to the requirements of the German Building Energy Act (GEG), Section 71k (Appendix B). Viessmann Climate Solutions has announced this in a manufacturer’s declaration ( Homeowners who opt for these units are therefore on the safe side in the long term: You can continue to heat with natural gas for the time being and are also well prepared when your gas supply is converted to hydrogen.  

"In addition to modern heat pumps, which are almost always the better solution, especially in new buildings, and hybrid devices for the combined use of environmental energy and fossil fuels, we offer another way to meet the requirements of the GEG with our convertible gas condensing boilers," explains Alexander Dauensteiner, Viessmann Product Line Owner. "In any case, trade partners and end customers will receive a heat generator that can be used to heat a house safely, efficiently and prepared for the possible use of 100% hydrogen in the future."

Conversion kits enable simple and time-saving conversion to hydrogen

The manufacturer’s declaration applies to the Vitodens 300-W (type B3HG), Vitodens 200-W (types B2HF, B2KF) and Vitodens 222-W (type B2LF) wall-mounted boilers and the Vitodens 333-F (type B3TG) and Vitodens 222-F (types B2TF, B2SF) floorstanding compact boilers. With  outputs of 1.9 to 32 kilowatts, they are primarily designed for use in single- and two-family homes and as floor heating systems. As standard, these heat generators can be operated with natural gas, bio natural gas, liquid gas (also bio LPG depending on the specification) and gas mixtures with up to 20 percent hydrogen. According to current plans, conversion kits will be available starting at the beginning of 2026 for converting units to run on pure hydrogen. This means that in future the conversion can be performed easily as part of the gas grid area transformation plan (for more information, see The certification of the units in combination with the conversion kits is performed according to the valid specifications of ZP 3100.100 and EN 15502.

GEG amendment suspends EE obligation for convertible gas heating systems

The GEG amendment, which becomes effective on January 1, 2024, is intended to make a decisive contribution to achieving Germany’s climate protection targets. While only heating systems that use at least 65% renewable energy will be permitted in new development areas, owners of older houses will only find out which heat supply options will be available to them in the future once their local municipality has drawn up a heating plan. In cities with over 100,000 inhabitants, the municipal heating plan must be available by June 30, 2026, and in smaller municipalities by June 30, 2028, at the latest. If it is necessary to install a new heating system beforehand, gas condensing boilers may be used, provided they can be gradually operated with an increasing proportion of green gases, such as biogas.

However, section 71k, paragraph 1, of the GEG makes a significant exception for gas heating units that can be converted to run on pure hydrogen, given that the local heat planning provides a hydrogen network, and the grid operator has submitted a binding plan for the conversion to the new fuel source by the end of 2044. In this case, the units can be installed without having to meet the requirements for the use of renewable energy.


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Viessmann gas condensing boilers from the Vitodens 300 and Vitodens 200 series manufactured from January 2024 can be converted for operation with 100 percent hydrogen if required.

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Viessmann Climate Solutions SE plans to offer corresponding conversion kits for converting wall-mounted and compact units to hydrogen starting at the beginning of 2026.

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