Viessmann Modernization Compass GEG 2025

Introduction

This guide, the Viessmann Modernization Compass, serves as a roadmap through the complexities of the GEG (Building Energy Act) and BEG-EM (Federal Funding for Efficient Buildings - Energy Efficiency Measures) subsidy landscape. It aims to help homeowners understand the benefits of modernizing their heating systems, explore technical options, and realize significant savings on heating costs by utilizing various energy sources.

Understanding GEG and BEG

Building Energy Act (GEG): This legislation sets the framework for Germany's goal of achieving CO₂-neutrality by 2045. It mandates a complete phase-out of fossil fuels for heating and hot water preparation, a process known as decarbonization.

Federal Funding for Efficient Buildings (BEG): Closely linked to the GEG, the BEG program provides financial incentives and subsidies to encourage the replacement of old heating systems with new ones that utilize renewable energy sources.

Your Modernization Roadmap

The German government has established specific requirements for adopting new heating systems and accessing subsidies. These requirements are based on the percentage of renewable energy used (the 'EE-quota'), municipal heat planning, and the size of the municipality. Essentially:

• 65% EE-Quota: New heating systems must utilize at least 65% renewable energy in existing buildings and new constructions.
• 100% EE-Quota: If your building has good thermal insulation or you plan a comprehensive energy-efficient renovation, installing a system that runs on 100% renewable energy is highly recommended.

100% Renewable Energy Solutions

Transitioning to 100% renewable energy for heating offers numerous advantages:

• Environmental Benefits: Significantly reduces CO₂ emissions. When combined with self-generated solar power, the system can be virtually emission-free. Biomass, like wood, is considered CO₂-neutral as it absorbs as much CO₂ during growth as it releases during combustion.
• Long-Term Security: Unlike finite fossil fuels, renewable energy sources like ambient heat (used by heat pumps) are inexhaustible and provide supply security, independent of fluctuating global energy prices.
• Cost Stability: The free and readily available nature of ambient heat and locally sourced biomass insulates homeowners from volatile energy price fluctuations, leading to predictable and stable heating costs.

Viessmann Vitocal 250-A (Air/Water Heat Pump)

This innovative monoblock heat pump offers reliable, compact, and environmentally friendly operation. It can be used for heating and cooling, features a natural refrigerant (R290 propane) with a low GWP, and is easily controlled via the ViCare app.

Key Features:

• Nominal heat output: 2.6 to 18.5 kW
• Ideal for modernization projects
• Highly efficient and sustainable operation
• Cooling function
• User-friendly control via ViCare app
• Natural refrigerant R290 (Propane) with low GWP

Funding Opportunity: Up to 70% subsidy is available for eligible households with an annual income of up to €40,000 when replacing an old gas or oil boiler.

Viessmann Vitoligno 300-C (Compact, Fully Automatic Pellet Boiler)

This fully automatic pellet boiler is versatile and suitable for various applications, from low-energy homes to those with higher heating demands. It offers flexible funding options.

Key Features:

• Nominal heat output: 2.4 to 48 kW
• Flexible fuel feeding
• Compact dimensions
• Automatic cleaning of the grate
• Ash box requires emptying only once or twice a year
• Low power consumption
• User-friendly control via ViCare app

Funding Opportunity: Attractive state subsidies are available for biomass boilers, including a speed bonus when combined with solar thermal, heat pumps, or photovoltaics.

65% Renewable Energy Solutions (Hybrid Systems)

Hybrid systems combine different energy sources to meet the 65% renewable energy quota, offering flexibility and efficiency.

Hybrid with Heat Pump and Gas

This option combines a Viessmann heat pump with a gas condensing boiler. The heat pump handles the primary heating load, while the gas boiler efficiently covers peak demand during very cold periods. Integrated energy management ensures optimal operation based on cost or sustainability.

Technology Options:

• Heat Pump + Gas Condensing Boiler: 87% gas saving, 0% electrical autarky.
• Heat Pump + Gas Condensing Boiler + Photovoltaics + Battery Storage: 87% gas saving, 43% electrical autarky.

Hybrid with Biomass and Renewable Energy

Combining biomass boilers with heat pumps or condensing units offers high efficiency and utilizes sustainable energy sources.

H₂-ready and Green Fuels Ready

Viessmann's modern gas condensing boilers are H₂-ready, meaning they can be prepared for a blend of up to 20% hydrogen in natural gas. Furthermore, Viessmann's Vitodens 3xx and 2xx series boilers can be converted to run on 100% hydrogen, ensuring future-proof heating solutions.

Green Fuels: Viessmann systems are also compatible with Green Fuels, such as HVO (vegetable oil) and PTL (power-to-liquid), which are CO₂-neutral alternative liquid fuels that can replace fossil heating oil.

Viessmann System Solutions

Viessmann offers a range of integrated system solutions designed for modernization:

• Vitocal 250-AH and Vitocrossal 300: Hybrid heat pump combined with a gas condensing boiler.
• Vitocal 150-A and Vitodens 200-W: Air/water heat pump complemented by a gas condensing wall-mounted unit.
• Vitocal 250-AH and ivo.smart water+: Hybrid heat pump paired with a water-guided pellet stove.
• Vitoligno 150-S and Vitoladens 300-C: Log wood gasifier boiler combined with an oil condensing boiler.

These systems are designed for high energy efficiency, space-saving installation, and offer attractive funding opportunities.

Benefits of Viessmann Heat Pumps

• Independence from fossil fuels
• Free, inexhaustible natural heat sources
• Low operating costs due to high efficiency ratings
• Reduced electricity costs (especially when combined with solar power)

Benefits of Viessmann Pellet Boilers

• Independence from fossil fuels
• Renewable, nearly CO₂-neutral fuel source
• High CO₂ savings compared to other heating systems
• Low fuel costs (pellets vs. oil)
• Versatile installation, utilizing space previously occupied by oil tanks

Self-Generated Solar Power

Generating your own solar power with Viessmann photovoltaic modules significantly reduces energy costs and provides independence from external electricity suppliers. Battery storage systems can further enhance this by storing surplus solar energy for later use.

Contact Information

Viessmann Deutschland GmbH
35108 Allendorf (Eder)
Phone: 06452 70-0
Website: www.viessmann.de
A Carrier Company

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For detailed information on hydrogen compatibility and Green Fuels, please visit: www.viessmann.de/hse and www.viessmann.de/H2ready