CEN/TC 57 - Central heating boilers

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;
(...)

This document specifies a method for the energy assessment of domestic/sanitary hot water storage tanks of up to 2 000 l.
Whilst this document does not cover water heaters intended primarily for direct heating, it does allow the provision of electric heating elements for auxiliary use.
Primary heating buffer tanks are not covered by this document. Heat losses of domestic hot water storage tanks integrated into combi boilers marketed as a single unit are not covered by this document.

This document is composed of two parts.
The first part supplements EN 303-1, EN 303-2, EN 303-4 and EN 304, hereafter called boiler standards. It specifies the supplementary requirements and tests for the construction, safety, rational use of energy, fitness for purpose, classification and marking related to the domestic hot water operation of oil-fired water heaters and combination boilers.
The domestic hot water is produced on either the instantaneous or storage principle. The domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
The second part covers the energy performance of domestic hot water production of the appliances covered by the first part.
This second part sets out a method for assessing the energy performance of the appliances. It defines a number of daily tapping cycles for each domestic hot water use such as kitchen, shower, bath and a combination of these, together with corresponding test procedures, enabling the energy performances of combination boilers and water heaters to be compared and matched to the needs of the user.
The heat output of the appliances covered by this standard does not exceed 400 kW.
In the case of combination boilers, with or without storage tank, domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
This standard only covers type testing.

This European Standard applies to the determination of the performances of heating boilers and combi boilers fired by liquid fuels. The requirements for the heating performances are laid down in EN 303 1:2016 and EN 303 2:2016.
This test code includes the requirements and recommendations for carrying out and evaluating the procedure for testing boilers and also the details of the technical conditions under which the tests will be carried out.
The requirements and the performance of testing for the sanitary hot water production of combi boilers are laid down in EN 303 6.

This European Standard applies to boilers used for central heating (heating boilers) with forced draught burners with a nominal heat output not exceeding 1 000 kW, which are operated either with negative pressure (natural draught boilers) or with positive pressure (pressurized boiler) in the combustion chamber, in accordance with the boiler instructions.
This European Standard specifies the necessary terminology, the requirements on the materials and testing of them, and marking requirements for heating boilers.
Particular requirements for boilers that can be used with open vented systems are contained in EN 303 4.
The requirements of this standard apply to heating boilers that are tested on an authorized test rig.
Boilers in accordance with this standard are designed for the heating of central heating installations in which the heat carrier is water, and the maximum allowable operating temperature of which is restricted to 100 °C. The maximum allowable operating pressure is 8 bar.
For boilers and water heaters (storage or continuous flow heater) this standard only applies to the parts which are necessarily subject to the operating conditions of the heating boiler (heating part).
This standard does not apply to gas boilers with atmospheric burners, boilers for solid fuels, boilers with oil vaporization burners. For these boilers there are further requirements.

This European Standard is applicable to boilers used for central heating in accordance with prEN 303 1:2016 up to a nominal heat output of 1 000 kW and EN 303 4 up to a nominal heat output of 70 kW with forced draught burners in accordance with EN 267 that are designed for operating with liquid fuels.
The performance requirements of this standard apply to type testing to heating boilers (standard, low temperature and condensing boilers) which are tested on a test rig in accordance with the test code given in EN 304.
This standard applies also to room sealed boilers as defined in EN 15035 regarding efficiency and emissions.
This standard can also be used as the basis for evaluation of boiler-/burner units.

This European Standard applies to heating boilers (e.g. with forced-draught burners (unit)) and burners equipped with a fan including all components specified by the manufacturer to be required for the designed boiler operation.
This European Standard also applies to heating boilers sold without burners.
This European Standard covers the required definitions, the system boundaries, the measurements for the determination of the electrical power consumption and, where applicable, the water side resistance in order to establish the electric auxiliary energy for:
   Oil-fired forced-draught burners in accordance with EN 267;
   Automatic forced-draught burners for gaseous fuels in accordance with EN 676;
   Flued oil stoves with vaporizing burners in accordance with EN 1;
   Heating boilers sold without burners for:
   Oil-fired forced-draught burners in accordance with EN 303-1 [6], EN 303-2 [7] and EN 304;
   Condensing boilers for liquid fuels in accordance with EN 15034;
   Room sealed boilers for fuel oil in accordance with EN 15035;
   Heating boilers - Heating boilers with forced-draught burners - Nominal heat output not exceeding 10 MW and maximum operating temperature of 110 °C in accordance with EN 14394;
   Pellet burners for small heating boilers in accordance with EN 15270.
NOTE   All measurements for boilers are carried out in the heating mode only. For hot water production this mode is also relevant.

This European Standard specifies the requirements and test methods for the design, manufacturing, safe operation and the rational energy usage for standard boilers and low temperature boilers (with "boiler" in the sense of "boiler body") from steel and cast iron to be equipped with separately marketed forced draught burners according to the relevant burner standards (for automatic forced draught burners for gaseous fuels see EN 676 and for atomising oil burners see EN 267) up to a nominal heat output of 10 MW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturer's instructions."
This European Standard specifies requirements for boilers with normal operating temperatures between 100 °C and 110 °C and has a "dual structure":
-   For boilers where the shut off temperature of the safety temperature limiter does not exceed 110 °C the Pressure Equipment Directive (PED) requires" Sound Engineering Practice",
-   For boilers where the shut off temperature of the safety temperature limiter exceeds 110 °C this European Standard specifies the requirements of the PED as stated in Annex ZB.
NOTE 1   The "maximum allowable temperature TS" is defined in the PED and its Guidelines."
Boilers in accordance with this European Standard are designed for the heating of central heating installations in which the heat carrier is water, and the maximum allowable operating temperature of which is up to 110 C and the maximum safety temperature limiter of 120 C. The maximum allowable operating pressure is 10 bar.
This standard does not apply to gas boilers with atmospheric burners, boilers for solid fuels, oil or gas fired condensation boilers, boilers with oil vaporisation burners. For these boilers there are further requirements.
For gas-fired central heating boilers equipped with a forced draught burner of nominal heat out put not exceeding 1000 kW,

This European Standard relates to pellet burners having a maximum heat input of not more than 70 kW, intended for fitting with appropriate boilers for hot water, and intended for high quality pellets in accordance with CEN/TS 14961:2005 Annex A. This standard contains requirements and test methods for safety, combustion quality, operating characteristics and maintenance of pellet burners and covers and also all external equipment that influences the safety systems. This standard also contains information on how to enable a correct match between pellet burner and boiler.
Pellet burners that are sold as a complete unit together with their own dedicated boilers are not covered.
NOTE   Other fuels will be considered in future amendments to this standard.

This European Standard applies to type CX3 central heating boilers as specified in 4.1, equipped with atomizing oil burners:
   type C13, type C33, and type C53 boilers, including their combustion air supply and combustion products evacuation ducts and their terminals;
   type C43 boilers including their connection ducts but without the chimney which is erected as a shared duct system and which is part of the building;
   type C63 boilers, including the connecting piece as specified in 3.7, if not integrated into the boiler;
   type C83 boilers, including their connection ducts but without the chimney which is part of the building;
   that have a nominal useful heat output below or equal to 70 kW;
   where the temperature of the water does not exceed 100 °C during normal operation;
   where the maximum water-side operating pressure does not exceed 8 bar.
This European Standard is intended to establish specific requirements and test methods for type C atomizing oil burning central heating boilers with respect to construction, safety, fitness for purpose, rational use of energy, classification and marking.
This European Standard only covers standard tests.
For boilers that produce domestic hot water by a drum or exchanger, integrated or juxtaposed, (by accumulation of instant production), this standard only applies to hot water reheating system components that are not subject to operating conditions applicable to the boiler heating system.
This European Standard covers units consisting of boilers equipped with burners that meet the requirements of EN 267, with the following exceptions:
   maximum NOx and CO emission values, estimated for boilers according to the classes defined in
EN 303-2;
   air factor value, defined by the manufacturer and stated in the boiler’s technical specifications;
   marking and/or burner data plate which may provide information for the boiler data plate;
   installation recommendations for installing the burner on the boiler included

This European Standard specifies test methods for airborne noise emissions from heat generators in a test laboratory or at the place of installation.
The test methods described in this European Standard, however, may be used for measuring the airborne noise emissions of the appliances and functions listed below.
This European Standard applies to following appliances regardless of their heat output and the fuel used:
   wall-mounted and floor-standing heating appliances;
   forced-draught burners;
   boilers/forced-draught burner units;
   boilers with freely allocated forced-draught burners;
   pellet burners.
According to this European Standard the manufacturer is allowed to choose an appropriate category of testing for the measured appliance.
This European Standard does not apply to:
   appliances used exclusively for heating drinking-water;
   function of heating drinking-water in so-called combined water-heaters;
   heat generators which work with air as the heat transfer medium;
   electrical heating appliances;
   structure-borne noise;
   sound transmission along the flue gas path.

This European Standard applies to heat generators according to EN 15036-1, which are connected to chimneys/ducts which discharge combustion products via a duct into open air.
The data measured according to this European Standard will probably be different from the noise radiated from the end of the chimney.
Readings from forced-draught burners complying with EN 267 or EN 676 are only applicable in practice if they have been taken in conjunction with a boiler. Noise emitted into chimneys/ducts by heat generators operating independently of indoor air can also be measured in accordance with this European Standard.
Boilers supplied with combined air inlet and exhaust terminal configuration where ducts are within an external wall can be measured according to one of the test methods detailed in EN 15036-1.
This European Standard describes the objective procedure for determining sound power levels LW, at the outlet of a heat generator that is emitting broad-band, narrow-band, or tonal continuous sound.
This European Standard is applicable to boilers designed to be connected to a chimney or flue duct with a duct size greater than or equal to 0,06 m and whose mean flue gas flow at the microphone head is less than 5 m/s.
This European Standard only applies for test purposes under laboratory conditions.

This European Standard specifies the requirements and test methods for the safety and efficiency of oil-fired air heaters using only forced draught oil burners, hereafter referred to as "appliances".
This European Standard applies to stationary and portable appliances. It also applies to appliances intended for outdoor installation. Provision of the heated air may be by means of ducting or may be directly into the heated space.
For the purpose of this standard the heat generation is by the combustion of liquid fuel oils as defined in EN 267 (gas oil with a viscosity at the burner inlet of 1,6 mm²/s (cSt) up to 6 mm²/s (cSt) at 20 °C). Alternatively, if the manufacturer requests, the fuel of kerosene may be used as defined in EN 304:1992. Kerosene with a viscosity at the burner of 1,3 mm2/s (cSt) to 2,9 mm2/s (cSt) at 20 °C) or other suitable liquid fuel oils may also be used.
This standard does not apply to:
- appliances intended for use in a single unit residential dwelling;
- appliances of the condensing type;
- appliances with atmospheric burners without a fan to assist the transportation of combustion air;
- dual purpose air conditioning appliances (heating and cooling);
- appliances where the air is heated by an intermediate fluid;
- appliances fitted with manual or automatic flue dampers;
- appliances having multiple heating units with a single flue;
- appliances fitted with more than one flue outlet.
This European Standard is applicable to appliances which are intended to be type tested.
NOTE   Requirements for appliances which are not type tested would need to be subject to further consideration.

This standard is applicable to heating boilers with forced draught oil burners up to a nominal heat output of 70 kW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturer's instructions. This standard specifies the necessary terminology, the requirements on the materials and testing of them, and marking requirements for heating boilers.

This document applies to the determination of the performances of heating boilers and combi boilers fired by liquid fuels. The requirements for the heating performances are laid down in EN 303-1 and EN 303-2.
This test code includes the requirements and recommendations for carrying out and evaluating the procedure for testing boilers and also the details of the technical conditions under which the tests will be carried out.
The requirements and the performance of testing for the sanitary hot water production of combi boilers are laid down in EN 303-6.

This document is applicable to boilers used for central heating in accordance with EN 303-1 up to a nominal heat output of 1 000 kW and EN 303-4 up to a nominal heat output of 70 kW with forced draught burners in accordance with EN 267 that are designed for operating with liquid fuels.
The performance requirements of this document apply to type testing to heating boilers (standard, low temperature and condensing boilers) which are tested on a test rig in accordance with the test code given in EN 304.
This document applies also to room sealed boilers as defined in EN 15035 regarding efficiency and emissions.
This document can also be used as the basis for evaluation of boiler-/burner units.

This document specifies a method for the energy assessment of domestic/sanitary hot water storage tanks of up to 2 000 l.
Whilst this document does not cover water heaters intended primarily for direct heating, it does allow the provision of electric heating elements for auxiliary use.
Primary heating buffer tanks are not covered by this document. Heat losses of domestic hot water storage tanks integrated into combi boilers marketed as a single unit are not covered by this document.

This document is composed of two parts.
The first part supplements EN 303-1, EN 303-2, EN 303-4 and EN 304, hereafter called boiler standards. It specifies the supplementary requirements and tests for the construction, safety, rational use of energy, fitness for purpose, classification and marking related to the domestic hot water operation of oil-fired water heaters and combination boilers.
The domestic hot water is produced on either the instantaneous or storage principle. The domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
The second part covers the energy performance of domestic hot water production of the appliances covered by the first part.
This second part sets out a method for assessing the energy performance of the appliances. It defines a number of daily tapping cycles for each domestic hot water use such as kitchen, shower, bath and a combination of these, together with corresponding test procedures, enabling the energy performances of combination boilers and water heaters to be compared and matched to the needs of the user.
The heat output of the appliances covered by this standard does not exceed 400 kW.
In the case of combination boilers, with or without storage tank, domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
This standard only covers type testing.

This document specifies the essential terms, constructional requirements, tests, energy assessment and marking of indirectly heated water storage tanks for primary water (buffer tanks), with a capacity not exceeding 2,000 l, an operating temperature not exceeding 95 °C, and an operating pressure not exceeding 1,0 MPa (10 bar).
This document covers metallic and plastic made buffer tanks.
Although this document does not consider any buffer tanks mainly intended for direct firing, it allows for the provision of electric heating elements for auxiliary purposes.
NOTE   The energy assessment is performed by EN 15332 or EN 12897.

PED and GAD related requirements

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;
(...)

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.
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. 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;
-   condensing boilers.
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).
(...)

This European Standard specifies a method for the energy assessment of a domestic hot water system comprising an external heating boiler of specified minimum output indirectly heating an unvented (closed) hot water tank of up to 1 500 l. Whilst tanks intended primarily for direct heating are not covered by this European Standard, it does allow the provision of electric heating elements for auxiliary use.

This standard supplements standards EN 303-1, EN 303-2, EN 303-4 and EN 304/A1 hereafter called boiler standards. It specifies the supplementary requirements and tests for the construction, safety, rational use of energy, fitness for purpose, classification and marking related to the domestic hot water operation of oil-fired combination boilers of nominal heat output not exceeding 70kW. The domestic hot water is produced on either the instantaneous or storage principle. The domestic hot water production is integrated or coupled, the whole being marketed as a single unit.

This European Standard applies to low-temperature boilers in accordance with EN 303-1/A1 and specifies the deviating boundary conditions for the heating-related tests on low-temperature boilers fired with liquid fuel.

The test code applies to the tests of the thermal performance of oil-fired heating boilers (hereafter called 'boilers') and combined boilers and water heaters. The requirements are laid down in EN 303 part 1 and EN 303 part 2. This standard includes the requirements and recommendations for carrying out and evaluating the procedure for testing boilers and also the details of the technical condtions under which the tests shall be carried out.

Replace the first paragraph by the following text :
"This European Standard applies to standard boilers and low-temperature boilers with forced draught burners with a nominal heat output not exceeding 1000 kW, which are operated either with negative pressure (natural draught boilers) or with positive pressure (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturers' instruction."
Delete the text in the 7th paragraph:
- condensing boilers, boilers with oil vaporisation burners and low temperature boilers,
and replace by:
- condensing boilers and boilers with oil vaporisation burners.
The note of the 7th paragraph has to be deleted.

This standard is applicable to heating boilers with burners using fans up to a nominal heat output of 1000 kW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturers' instructions. This standard specifies the necessary terminology, the requirements on the materials and testing of them, and marking requirements for heating boilers. Particular requirements for boilers which can be used with open vented systems are contained in prEN 303-4.

This European Standard applies to oil-fired heating boilers, which are declared by the manufacturer to be condensing boilers up to a nominal heat output of 1 000 kW supplied as a unit with an atomizing oil burner which meets the requirements of EN 267.

This European Standard applies to oil-fired heating boilers, which are declared by the manufacturer to be condensing boilers up to a nominal heat output of 1 000 kW supplied as a unit with an atomizing oil burner which meets the requirements of EN 267.
NOTE   This European Standard defines three classes of oil fired boilers with efficiency requirements higher than those given for low temperature boilers in the Boiler Efficiency Directive (BED) 94/42/EEC.
This European Standard completes/modifies EN 303-1, EN 303-2 and EN 304 and specifies supplementary requirements for condensing boilers.

add new subclause:
This European Standard applies to low-temperature boilers in accordance with EN 303-1/A1 and specifies the heating-related requirements necessary for liquid fuels for low-temperature boilers and the required additional duration test for oil-fired low-temperature boilers.

This standard is applicable to heating boilers in accordance with prEN 303-1 up to a nominal heat output of 1000 kW and prEN 303-4 up to a nominal heat output of 70 kW with atomizing oil burners in accordance with EN 267 which are designed for operating with liquid fuels.  The requirements of this standard apply to type testing to heating boilers which are tested on a test rig in accordance with the test code given in EN 304.  This standard specifies the necessary heating technical requirements for heating boilers with liquid fuels.  NOTE: This Standard can also be used as the basis for evaluation of package boiler/burner units.

This standard applies to heating boilers up to a nominal heat output of 300 kW which are designed for the burning of solid fuels only and are operated according to the instructions of the boiler manufacturer either with negative pressure or with positive pressure in the combustion chamber.

This European Standard specifies the requirements and test methods for the construction, the safety and the rational energy usage for heating boilers (standard-heating and low temperature boilers) fired by liquid fuels from steel and cast iron with burners according to the relevant burner standards (for atomising oil burners, see. EN 267) up to a nominal heat output of 10 MW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurised boiler) in the combustion chamber, in accordance with the boiler manufacturer's instructions
Boilers in accordance with this European Standard are designed for the heating of central heating installations in which the heat carrier is water, and the maximum allowable operating temperature of which is up to 110 °C and the maximum safety temperature limiter of 120 °C. The maximum allowable operating pressure is 10 bar.
This standard does not apply to gas boilers with atmospheric burners, boilers for solid fuels, oil or gas fired condensation boilers, boilers with oil vaporisation burners. For these boilers there are further requirements.
For gas-fired central heating boilers equipped with a forced draught burner of nominal heat out put not exceeding 1000 kW, see prEN 303-7.
For shell boilers with a nominal heat output exceeding 10 MW and a maximum safety temperature limiter exceeding 120 °C, see EN 12953 series.
NOTE   Definitions for heating boiler and low temperature boiler see Council Directive 92/42/EEC.

This standard applies to heating boilers with burners using fans up to a nominal heat output of 300 kW. They are operated, either with negative pressure (natural draught boiler) or with positive pressure (pressurized boiler) in the combustion chamber, in accordance with the boiler manufacturer's instructions. Particular requirements for boilers which can only be used with open vents are contained in a separate document (being prepared). The requirements of this standard apply to heating boilers which are tested on an authorized test rig.

This standard applies to heating boilers in accordance with EN 303-1 with atomizing oil burners in accordance with EN 267 up to a nominal heat output of 300 kW which are designed for operating with liquid fuels with a viscosity at the burner inlet of (5,5 +0,5) mm2/s at a temperature of 20°C and a density of 0,83 - 0,86 g/cm3 at a temperature of 15°C. The requirements of this standard apply to heating boilers which are tested on a test rig in accordance with the test code given in EN 304 part 1.