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Over a dozen years ago, three basic emission classes of boilers were distinguished - from 1 to 3 (best / highest), which was defined in EN 303-5 from 2002.

However, within 10 years new regulations were prepared, which were included in the updated standard in 2012. They presented three new classes with stricter emission conditions: from 3 to 5, where 5 is the most restrictive class, and thus the best.

It is worth noting that many older models of boilers still do not have any class in the nameplate, because previously it was not required. Only people trying to get a subsidy to buy a boiler tried to get it. However, the new standard already enforces the designation of the class on each boiler, according to their degree of harmfulness to the environment.

What are the requirements?

To obtain a rating plate with class 5, the heating boiler must meet very restrictive conditions, which is defined in EN 303-5: 2002. Among them you can mention, among others:

  • ● The CO emission limit value is not more than 500 mg / m3 (previously: 3000 mg / m3),
  • ● The limit value for emission of mine dust is not more than 40 mg / m3 (previously: 125 mg / m3),
  • ●The limit value of emissions of gaseous organic pollutants is not more than 20 mg / m3 (previously 100 mg / m3).

These are very large changes, forcing producers to use much more advanced technologies, as well as more restrictive instructions for fuels that can be burned. One of them is primarily dry fuel, which can also be self-dried by ventilation in the device.

The new regulations have been in force since October 1, 2017. This means that each boiler produced after this date must comply with the 5th class emission requirements. This involves a price increase not only for the device, but also for the permitted fuel.


EU Commission Regulation 2015/1189 of 28 April 2015 introduced the Ecodesign Directive, which will become effective in 2020. Additional provisions will be introduced for seasonal energy efficiency for carbon monoxide, nitrogen, organic gaseous compounds and particulate matter.