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First hydrogen grid enters regular operation in Germany: Vaillant supplies H₂ heating technology
How a field test becomes reality
Well-kept houses, hedges, carports, bicycles outside the garages. A neighbourhood which can be found in many places across Europe. And yet something remarkable is happening in Hohenwart, a town in Bavaria, Germany, with a population of around 5,000: people are no longer heating their homes with natural gas. They are heating them with hydrogen.
A decisive milestone was recently reached: the ‘H2Direkt’ research and pilot project has evolved into ‘H2Dahoam’, Germany’s first hydrogen grid in permanent regular operation. The project demonstrates how climate-neutral heating with hydrogen can work in practice – safely, suitable for everyday use and based on existing infrastructure.
Following the end of the funding period, the project will be continued by “Energie Südbayern GmbH” (ESB) as the energy supplier and “Energienetze Bayern GmbH” as the grid operator. Vaillant Germany is supporting the implementation as a technology partner.
The housing estate, which is around ten years old and features modern gas infrastructure, offered ideal conditions for this upgrade. Amid detached houses, gardens, and an established neighbourhood, a real-world example of tomorrow's heating supply has been created.
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From pilot project to full-scale operation
The small stretch of road between Munich and Ingolstadt has attracted international attention over the past two years. A total of ten detached and semi-detached houses, as well as one commercial building, were supplied entirely with green hydrogen as part of the ‘H2Direkt’ project. Hydrogen flowed through the existing grid instead of natural gas.
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Vaillant’s condensing boilers, designed to run on 100 per cent hydrogen, proved their reliability over two full heating seasons.
With the successful conversion of the test units to ecoTEC plus VC gas condensing boilers from series production, the pilot project officially transitioned to regular operation and became ‘H2Dahoam’. Thanks to a special conversion kit, the boilers can also operate on 100 per cent hydrogen.
For households, this meant hardly any changes. Apart from the heat generator and the flue gas system, only a few components needed to be adapted. It is precisely this that the project partners see as a key driver for the heating transition in the existing building stock: existing networks and supply structures can continue to be used without the need for costly refurbishments or the creation of entirely new infrastructure.
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Engaging people – and building trust
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In Hohenwart, the hydrogen supply isn’t just technology – it’s also been embraced by the community. The participating families made a conscious decision to join the project and are continuing to take part following the pilot phase.
“At first, of course, we had questions about the safety of the infrastructure,” say Christina and Christoph Schartel from Hohenwart. The family of three lives in a detached house built in 2020 with around 186 square metres of living space, which has been heated with hydrogen since the start of the project. “But the switch went smoothly and there was no difference to before in our day-to-day lives. Heating costs are also expected to remain roughly comparable to those of a gas supply. That’s why we’re sticking with hydrogen, because for us it’s a meaningful contribution to a climate-friendly future.”
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Jürgen Haindl, Mayor of Hohenwart, is also delighted with this successful milestone. “A project like this takes courage – from everyone involved. And you have to get people on board,” reflects the mayor. “The transition to regular operation is a key step towards making hydrogen a reality. That’s important for credibility. Because when something works in practice, word gets round. At first, people laughed at us – but now we’re earning a lot of respect for it.”
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The installers involved also give a positive assessment.
“The appliance replacement was completed within a week and was very straightforward from a technical point of view. Although the condensing boilers differ in some details, the dimensions and connections match the existing systems exactly,” explain Anton Selensky, owner of the installer company “Haustechnik Stachel”, and Bernd Mantsch, owner of “Mantsch Heizung”. “Throughout the entire field test phase, there were only two minor service calls. The switch from gas to hydrogen can be made without significant effort or high additional costs for customers.”
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Looking ahead and achieving greater independence
The project’s development does not end with the successful transition to regular operation – quite the contrary. The next phase of expansion is already planned: the local production and storage of green hydrogen directly on site. In the future, the supply is to be gradually extended to other parts of Hohenwart and neighbouring municipalities. In the long term, the project partners’ vision is to achieve a connection rate of up to 50 per cent of households.
To this end, an electrolyser is to be built in the immediate vicinity of the existing feed-in facility. The necessary development plan has already been unanimously approved by the Hohenwart Municipal Council. In the long term, the plant is to be powered by regionally generated photovoltaic electricity. The concept is complemented by a hydrogen storage facility capable of absorbing surplus energy and making it available as and when required. The aim is a largely independent, decentralised and climate-neutral energy supply with short transport distances and long-term security of supply.
An open approach to technology
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For Vaillant Germany, ‘H2Dahoam’ is far more than just a successful field test. The project in Hohenwart demonstrates how modern heating technology can utilise hydrogen via existing infrastructure in the building sector. For Vaillant, the heating transition means an open approach to technology – with a focus on heat pumps as a key technology and hydrogen-compatible gas boilers as a complementary solution for a climate-neutral heat supply. With the systems deployed in Hohenwart, Vaillant is among the first manufacturers to implement the operation of gas condensing boilers running on 100 per cent hydrogen in existing buildings.
Hohenwart is already demonstrating what this additional component of tomorrow’s heating supply could look like: future-orientated, reliable, and proven in everyday use.
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