DS/EN 303-5:2021

Heating boilers – Part 5: Heating boilers for solid fuels, manually and automatically stoked, nominal heat output of up to 500 kW – Terminology, requirements, testing and marking

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Please note that this standard has not yet been harmonised and thus cannot be used for CE marking. Until harmonisation of this standard has been achieved, please use one of the following standards: 


Please note that this standard has not yet been harmonised and thus cannot be used for CE marking. Until harmonisation of this standard has been achieved, please use one of the following standards: 


Building Regulations 2015​

Building work in new and altered buildings in Denmark

The Building Regulations contain the Danish rules for building work in new buildings, extensions, conversions and other rebuilding work, as well as changes in the use of buildings that are important in relation to the Danish Building Act or the Building Regulations, the demolition of buildings and alterations and other rebuilding work that may affect the consumption of energy in the building. The Building Regulations apply to building work carried out in the Danish market.

Their primary field of application is multi-storey buildings for residential purposes and all kinds of commercial, industrial and institutional buildings, including the categories listed in section 11 of the Danish Building Act, single-family houses for permanent residence, either as detached single-family houses or linked single-family houses, holiday homes in summer house areas, allotment sheds, campsite cabins and garages, outbuildings, and other secondary buildings.

You can read more about the Danish Building Regulations here:  http://bygningsreglementet.dk/


1.1 General

This European Standard applies to heating boilers including safety devices up to a nominal heat output of 500 kW which are designed for the burning of solid fuels only and are operated according to the instructions of the boiler manufacturer.

This European Standard deals with significant hazards, hazardous situations and events relevant to heating boilers used as intended and under the conditions foreseen by the manufacturer (see Clause 4).

The boilers may operate under natural draught or forced draught. The stoking may work manually or automatically.

The boilers may operate under room sealed conditions in case of supervised under pressure in the combustion chamber.

The boilers may operate in condensing condition.

NOTE – This European Standard deals with boilers which are both within and outside of the scope of the Machinery

Directive 2006/42/EC.

This European Standard contains requirements and test methods for safety, combustion quality, operating characteristics, marking and maintenance of heating boilers and secondary emission reduction appliances and efficiency improvement appliances. It also covers all external equipment that influences the safety systems (e.g. back burning safety device, integral fuel hopper).

This European Standard covers only boilers that include burners as a unit. The standard applies to the combination of a boiler body with a solid fuel burner according to EN 15270 as a unit only when the whole unit is tested in accordance with this European Standard.

Heating boilers in accordance with this European Standard are designed for central heating installations where the heat carrier is water and the maximum allowable temperature is 110 °C, and which can operate at a maximum allowable operating pressure of 6 bars. For heating boilers with a built-in or attached water heater (storage or continuous flow heater), this European Standard only applies to those parts of the water heater which are necessarily subject to the operating conditions of the heating boiler (heating part).

This European Standard does not apply to:

heating boilers and other heating appliances which are also designed for the direct heating of the place of installation;

cooking appliances;

the design and construction of external fuel storage and transportation devices prior to the safety devices of the boiler;

room sealed applications above a nominal heat output > 70 kW or operated with positive pressure in the combustion chamber or operated under natural draught;

This European Standard specifies the necessary terminology for solid fuel heating boilers, the control and safety related requirements, the design requirements, the technical heating requirements (taking into account the environmental requirements) and testing, as well as the marking requirements.

This European Standard is not applicable to heating boilers which are tested before the date of its publication as an EN (European Standard).

1.2 Fuels

These boilers may burn either fossil fuels, biogenic fuels or other fuels such as peat, as specified for their use by the boiler manufacturer, in accordance with the requirements of this European Standard.

Solid fuels included in this European Standard are categorised as follows.

1.2.1 Biogenic fuels

Biomass in a natural state, in the form of:

Adaptation to new fuels standards and consideration of new fuels standards in preparation.

A log wood with moisture content w ≤ 25 %, according to EN 14961-5;

B1 chipped wood (wood chipped by machine, usually up to a maximum length of 15 cm) with moisture content from w 15 % to w 35 %, according to EN 14961-4;

B2 chipped wood as under B1, except with moisture content w > 35 %;

C1 compressed wood (e.g. pellets without additives, made of wood and/or bark particles; natural binding agents such as molasses, vegetable paraffins and starch are permitted), pellets according to EN 14961-2;


Number of pages: 93

Published: 2021-04-14

Date of approval: 2021-04-12

International relationships : EN 303-5:2021 IDT

ICS: 91.140.10 - Central heating systems

Item number: M322472



  • CEN/TC 57
  • CEN/TC 57/WG 1

Danish committee