Gas condensing boilers - technology for various needs

Viessmann offers a range of technologies for convenient heat generation from natural gas, meeting diverse needs and situations. The portfolio covers gas heating systems for both new and existing buildings. Large-scale projects in residential, commercial and public sectors are also possible.

Compact boilers are space-saving wonders

Wall-mounted gas condensing boilers are particularly suitable for new builds and small apartments. These extremely compact units can be installed almost anywhere. They are used either solely for domestic hot water preparation or for space heating. Both versions operate on the instantaneous water heating principle, so they typically do not have a storage tank and heat water only on demand. This allows very quick response to changing requirements. The drawback is that hot water is not available instantly; to avoid running water for long before it turns hot, some wall-mounted units include a small built-in storage tank.

Floor-standing gas condensing boilers for higher efficiency with high hot water demand

Floor-standing condensing boilers take up slightly more space, mainly due to a larger storage water heater that keeps hot water at a constant temperature for longer. This is particularly efficient when larger volumes of water are regularly required.

If you plan to connect a solar thermal system for DHW preparation, we recommend a floor-standing gas condensing boiler with an integrated solar indirect coil. It is installed on a buffer cylinder or near the draw-off point and heats the hot water. In such combined systems, heating water and domestic hot water do not mix. Floor-standing units are designed for dual-mode operation, making it easy to combine them with another heat generator to meet demand. Thanks to modern technology, Viessmann gas condensing boilers reliably and efficiently supply heat to detached houses, semi-detached homes and apartment buildings.

Floor-standing gas condensing boilers are also available in larger sizes. They are mainly used in buildings with high heat demand, such as multi-apartment complexes, public buildings and commercial spaces. With cascade functionality, multiple units can be quickly connected to form a single system and provide reliable heat.

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Combining climate protection and financial benefits

Vitodens 111-F gas condensing boiler.

In Germany alone, around two million heating systems older than 25 years are still in use. Replacing them with high-efficiency gas condensing boilers can save a lot of energy - up to 35 percent when combined with solar technology. This would correspond to ten percent of Germany’s total energy needs while reducing CO₂ emissions by up to 54 million tons per year.

Such savings are possible because condensing technology uses energy extremely efficiently, converting virtually all of the fuel’s calorific value into heat. Choosing a gas condensing boiler helps keep heating costs low long-term and reduces environmental impact, since less combustion means lower CO₂ emissions.

All Viessmann gas condensing boilers meet EU-wide requirements for efficient condensing technology. 98 percent or more of the consumed energy is converted into heat. With such unmatched efficiency, choosing these systems contributes directly to climate and environmental protection.

How gas heating with condensing technology works

Condensing technology utilizes not only the measurable heat of the hot flue gases (lower heating value) but also the water vapor content (higher heating value). This contains “latent” heat that older systems would release through the chimney. By routing the flue gases through a heat exchanger until the vapor condenses, this latent heat is recovered and used to heat the heating water.

Carsten Kuhlmann explains how condensing technology works

You will also find a detailed description of the technology in our section on gas condensing systems. Additional comprehensive information is available in the heizung.de gas heating guide.

Future-proof and reliable heating technology available today

There is a growing call to use resource-saving heating technologies. New gas condensing boilers must operate not only cleanly but also sustainably. In response, Viessmann has developed gas condensing systems that are ready for the future. Thanks to combustion control, the boilers automatically adapt to various gas types, including biogas blends. They are also suitable for operation with natural gas-hydrogen mixtures containing up to 20 percent hydrogen, with the aim to increase this proportion over time.

Learn more about Viessmann "H2 ready" heating appliances.

Advantages of wall-mounted and floor-standing gas condensing boilers

Condensing technology is now the benchmark for new gas heating systems. Owners who choose this technology benefit from many advantages:

Choosing a gas condensing heating system also means you do not need a fuel storage room at home. Where a gas connection is available, a tank is unnecessary. Compact condensing boilers save space.

A house with a Viessmann gas condensing boiler in the basement and a solar thermal system on the roof.

Easy to combine with renewable energy heating systems

As mentioned earlier, one advantage of condensing technology is its high compatibility. In practice, most boilers are factory-prepared for combined operation. Pairing a gas condensing boiler with a solar thermal system is both ecological and economical: the solar system heats domestic hot water using free solar energy, reducing the boiler’s workload and heating costs.

Combining with a heat pump is another option. In a dual-mode setup, the heat pump supplies DHW and space heating most of the time, while the gas boiler covers peak loads during very cold periods.

Viessmann services

App-based operation, extended warranty services or heat supply contracts - learn more about Viessmann’s broad service offering.

Product range

Whether wall-mounted gas condensing boilers, floor-standing units with an integrated solar indirect coil or cascade systems for high heat demand, Viessmann offers suitable solutions for a wide range of needs.

Author: viessmann.lv