Class 5

★★★★★ Class 5 according to EN 303-5:2021 - the highest standard for biomass boilers ★★★★★

The EN 303-5:2021+A1:2022 standard is a European standard that defines the technical requirements, test methods and criteria for the classification of hot water boilers fired by solid fuels, including wood chips and wood pellets, with a nominal thermal output of up to 500 kW. Within this standard, Class 5 denotes the highest level of quality, efficiency and environmental friendliness.

❔ What is Class 5?

Class 5 is a designation for boilers that meet the strictest requirements in terms of:

  1. Energy efficiency - boilers must have very high efficiency, which means that they maximize the energy from the fuel with minimal losses.
  2. Low emissions of harmful substances - including particulate matter (PM), carbon monoxide (CO), organic gaseous compounds (OGC) and nitrogen oxides (NOx).
  3. Safety and reliability – devices must pass rigorous safety system tests, including flashback protection, temperature and pressure control, and operation in condensing conditions.

☑ Key advantages of class 5 boilers

  1. Environmental friendliness: Class 5 boilers significantly reduce emissions of harmful substances compared to boilers of lower classes. This contributes to better air quality and reduced negative environmental impact, which is especially important in urban and densely populated areas.
  2. Compliance with regulations and incentives: In many European countries, including Croatia, class 5 boilers are the only ones that qualify for state subsidies and incentives for the use of renewable energy sources. Also, an increasing number of local and regional regulations prohibit the installation of lower class boilers.
  3. Higher long-term profitability: Although the initial investment in class 5 boilers is somewhat higher, their high efficiency and lower operating costs (lower fuel consumption, less maintenance) bring significant savings in the long run.
  4. Automation and comfort Most class 5 boilers come with advanced control systems, automatic fuel dosing, heat exchanger cleaning and remote control via the Internet or mobile applications.

Technical requirements according to EN 303-5:2021+A1:2022

The standard prescribes precise test methods and limit values for emissions and efficiency. For example:

  • The minimum seasonal efficiency must be above 90% for pellet boilers.
  • CO emissions must be very low.
  • Particulate matter emissions must be very low.
  • Boilers must be tested under real operating conditions, including different load regimes.

Conclusion

Choosing a Class 5 boiler according to EN 303-5:2021 is not just a technical choice – it is a responsible decision that contributes to environmental protection, community health and long-term energy sustainability. Such boilers represent the pinnacle of biomass heating technology and are the ideal choice for users who want to combine efficiency, comfort and environmental awareness.