Unknown BS EN 525 2009 ICS 97 100 20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Non domestic direct gas fired forced convection air heaters for space heati[.]
Appliance and its constituent parts
3.1.1 non-domestic air heater appliance designed for the heating and/or ventilation of a building other than a residential dwelling
A forced convection air heater is an appliance specifically designed to deliver space heating from a central source It effectively distributes heated air using an air moving device, either through ductwork or directly into the area that requires heating.
3.1.3 direct fired forced convection air heater forced convection air heater in which the products of combustion mix with the heated air being supplied to the space
3,1,4 high temperature direct fired forced convection air heater direct fired forced convection air heater designed to operate with an air temperature rise through the appliance greater than 60 K
3.1.5 low temperature direct fired forced convection air heater direct fired forced convection air heater designed to operate with a maximum air temperature rise through the appliance of 60 K or less
An appliance designed for downstream air re-circulation allows a portion of the heated air to be returned to the unit after the burner, enabling efficient redistribution of warmth.
An appliance designed for upstream air re-circulation allows a portion of the heated air to be returned to the unit before the burner, enabling efficient redistribution of warmth.
3.1.8 profile plates fixed or adjustable plates fitted for the purpose of setting the air flow velocity across the burner
3.1.9 gas inlet connection part of the appliance intended to be connected to the gas supply
3.1.10 combustion chamber part of the appliance in which the principal combustion process takes place
3.1.11 mechanical joint mechanical means of obtaining soundness means of ensuring the soundness of an assembly of several (generally metallic) parts without the use of liquids (e.g pastes and tapes)
EXAMPLE Metal to metal joints; conical joints; toroidal sealing rings (“O” rings); or flat joints
3.1.12 gas circuit part of the appliance that conveys or contains the gas between the appliance gas inlet connection and the burner(s)
A restrictor device featuring an orifice is installed in the gas circuit to generate a pressure drop, effectively lowering the gas pressure at the burner to a specified level based on the supply pressure and flow rate.
3.1.14 gas rate adjuster component allowing an authorised person to set the gas rate of the burner to a predetermined value according to the supply conditions
NOTE 1 Adjustment can be progressive (screw adjuster) or in discrete steps (by changing restrictors)
NOTE 2 The adjusting screw of an adjustable regulator is regarded as a gas rate adjuster
NOTE 3 The action of adjusting this device is called “adjusting the gas rate.”
NOTE 4 A factory sealed gas rate adjuster is considered to be non-existent
3.1.15 setting an adjuster immobilizing a gas rate adjuster (by some means such as e.g a screw) after the gas rate has been adjusted by the manufacturer or installer
3.1.16 sealing an adjuster setting of an adjuster using a material such that any attempt to change the adjustment breaks the sealing material and makes the interference with the adjuster apparent
NOTE 1 The adjuster is then said to be "sealed" in its adjustment position
NOTE 2 A factory sealed adjuster is considered to be non-existent
A regulator is deemed non-existent if it is factory sealed in a manner that prevents it from functioning within the supply pressure range appropriate for its appliance category.
An adjuster or control, such as those regulating temperature or pressure, is considered "put out of service" when it is rendered inactive and sealed in that position.
NOTE The burner unit then functions as if this device has been removed
3.1.18 injector component that admits the gas into a burner
3.1.19 main burner burner that is intended to assure the thermal function of the appliance and is generally called the burner
3.1.20 ignition device means (e.g flame, electrical ignition device or other device) used to ignite the gas at the ignition burner or at the main burner
NOTE This device can operate intermittently or permanently
3.1.21 ignition burner burner whose flame is intended to ignite another burner
3.1.22 aeration adjuster device enabling the air to be set at the desired value according to the supply conditions
NOTE The action of adjusting this device is called "adjusting the aeration"
The range rating device is a component designed for installers to modify the heat input of an appliance, aligning it with the manufacturer's specified range to meet the specific heating needs of the installation Adjustments can be made progressively, such as through a screw adjuster, or in discrete steps by replacing restrictors.
Adjustment, control and safety devices
3.2.1 automatic burner control system system comprising at least a programming unit and all the elements of a flame detector device
NOTE The various functions of an automatic burner control system may be in one or more housings [EN 298:2003]
The programming unit device responds to signals from control and safety devices, issuing control commands and managing the start-up sequence It supervises burner operation, facilitates controlled shut-downs, and initiates safety shut-downs and lock-outs when necessary.
NOTE The programming unit follows a predetermined sequence of actions and always operates in conjunction with a flame detector device [EN 298:2003]
3.2.3 programme sequence of control operations determined by the programming unit involving switching on, starting up, supervising and switching off the burner
NOTE Safety actions such as safety shut down and lock out are also part of the programme [EN 298:2003]
3.2.4 flame supervision device that, in response to a signal from the flame detector, keeps the gas supply open and shuts it off in the absence of the supervised flame
3.2.5 flame detector device device by which the presence of a flame is detected and signalled
A flame detection system typically includes a flame sensor, an amplifier, and a relay for signal transmission These components, except for the flame sensor itself, can often be housed together for integration with a programming unit, as outlined in EN 298:2003.
3.2.6 flame signal signal given by the flame detector device, normally when the flame sensor senses a flame [EN 298:2003]
3.2.7 flame simulation condition which occurs when the flame signal indicates the presence of a flame when in reality no flame is present [EN 298:2003]
3.2.8 pressure regulator device which maintains the outlet pressure constant independent of the variations in inlet pressure and/or flow rate within defined limits
3.2.9 adjustable pressure regulator regulator provided with means for changing the outlet pressure setting
3.2.10 volume regulator device which maintains the gas rate constant within a given tolerance, independent of the upstream pressure
3.2.11 automatic shut-off valve valve designed to open when energized and to close automatically when de-energized
A control thermostat is a device that regulates the operation of an appliance by managing its on/off, high/low, or modulating functions This device ensures that the temperature is maintained automatically within a specified tolerance at a predetermined value.
The overheat cut-off device is a crucial safety feature that automatically shuts off and locks the gas supply to prevent damage to the appliance and ensure safety This device requires manual intervention to restore the gas supply, highlighting its importance in maintaining operational safety.
NOTE This device is preset and sealed by the appliance manufacturer
3.2.14 temperature sensing element; temperature sensor component that detects the temperature of the environment to be supervised or controlled
3.2.15 modulating control automatic control by which the heat input of the appliance can be varied in a continuous manner between the nominal heat input and a minimum value
3.2.16 high/low control automatic control which permits an appliance to operate either at the nominal heat input or at a fixed reduced heat input
3.2.17 vent valve normally open automatic valve fitted between two automatic shut-off valves and intended to vent any small leakages of gas
3.2.18 air flow proving device device which monitors and proves the existence of an adequate flow of air for combustion and, where appropriate, for dilution
3.2.19 proof of closure indicator device fitted to a Class A, B or C automatic shut-off valve with mechanical overtravel which proves the valve to be in the closed position
3.2.20 closed position indicator device fitted to a Class A, B or C automatic shut-off valve which indicates when the valve is in the nominally closed position
A valve proving system is designed to verify the effective closure of start gas or main gas safety shut-off valves This system is also capable of detecting minor gas leakage rates, utilizing methods such as pressure or vacuum proving systems.
Appliance operation
V volume of gas consumed by the appliance in unit time during continuous operation
NOTE The volume flow rate is expressed in cubic metres per hour (m 3 /h), litres per minute (l/min), cubic decimetres per hour (dm 3 /h) or cubic decimetres per second (dm 3 /s) [EN 437:2003]
M mass of gas consumed by the appliance in unit time during continuous operation
NOTE The mass flow rate is expressed in kilograms per hour (kg/h) or grams per hour (g/h) [EN 437:2003]
Q quantity of energy used in unit time corresponding to the volumetric or mass flow rates: the calorific value used being the net or gross calorific value
NOTE the heat input is expressed in kilowatts (kW) [EN 437:2003]
Q n value of the heat input (kW) declared by the manufacturer
3.3.5 flame stability characteristic of flames which remain on the burner ports or in the flame reception zone intended by the construction
3.3.6 flame lift total or partial lifting of the base of the flame away from the burner port or the flame reception zone provided by the design
NOTE Flame lift may cause the flame to blow out (i.e extinction of the air-gas mixture)
3.3.7 light-back entry of a flame into the body of the burner
Light-back at the injector refers to the ignition of gas at the injector, which can occur due to flame propagation from the burner or backflow of flame into the burner itself.
3.3.9 sooting phenomenon appearing during incomplete combustion and characterized by deposits of soot on the surfaces or parts in contact with the combustion products or with the flame
3.3.10 yellow tipping yellowing of the tip of the blue cone of an aerated flame
The first safety time interval is defined as the duration between the energization and de-energization of the ignition burner gas valve, start gas valve, or main gas valve, depending on the application This interval is crucial, as it is triggered when the flame detector indicates the absence of a flame at its conclusion.
NOTE Where there is no second safety time, this is called the safety time
In the context of safety protocols, the second safety time refers to the interval between energizing and de-energizing the main gas valve when a flame detector indicates the absence of a flame, specifically following the initial safety time associated with either an ignition burner or starting a gas flame.
3.3.13 start gas gas that is supplied at the start gas rate to establish the start gas flame
3.3.14 start gas rate restricted gas flow rate admitted either to a separate ignition burner or to the main burner during the first safety time
3.3.15 start gas flame flame established at the start gas rate either at the main burner or at a separate ignition burner
The start gas flame proving period is the interval that occurs between the conclusion of the first safety time and the initiation of the second safety time This period is crucial for verifying the stability of the start gas flame.
3.3.17 running condition condition of the system in which the burner is in normal operation under the supervision of the programming unit and its flame detector device
3.3.18 controlled shut-down process by which the power to the gas shut-off valve(s) is removed immediately, e.g as a result of the action of a controlling function [EN 298:2003]
3.3.19 safety shut-down process which is effected immediately following the response of a protection device or a fault in the automatic burner control system and puts the burner out of operation
NOTE The resulting state of the system is defined by deactivatioed terminals for the gas shut-off valves and the ignition device [EN 298:2003]
The non-volatile lock-out safety shut-down condition ensures that the system can only be restarted through a manual reset, preventing any other means of reactivation [EN 298:2003].
A volatile lock-out is a safety shut-down condition in a system that requires either a manual reset or an interruption and restoration of the electrical supply to restart.
3.3.21 spark restoration process by which, after disappearance of the flame signal, the ignition device is energized again without the gas supply having been totally interrupted
This process concludes with either the restoration of the running condition or, in the absence of a flame signal after the safety time, a non-volatile lock-out.
The automatic recycling process ensures that if there is a loss of flame or an accidental interruption during the operation of an appliance, the gas supply is halted Subsequently, the entire start sequence is automatically restarted to maintain safety and functionality.
This process concludes with either the restoration of the running condition or, in the absence of a flame signal after the safety time, a non-volatile lock-out if the cause of the interruption remains unresolved.
3.3.23 extinction safety time time interval between extinction of the supervised flame and the gas supply to the main burner and/or to the ignition burner being shut off
3.3.24 no-air condition condition of the air proving device in which the device is checked for correct operation at zero air flow
3.3.25 proved air flow minimum air flow at which the air proving device indicates the presence of air flow
3.3.26 safe-start check check provided by a protective circuit on start up leading to safety shut-down or non-volatile lockout if a fault condition is present
Gases
3.4.1 test gases gases intended for the verification of the operational characteristics of appliances using combustible gases They comprise the reference and the limit gases [EN 437:2003]
3.4.2 reference gases test gases with which appliances operate under nominal conditions when they are supplied at the corresponding normal pressure [EN 437:2003]
3.4.3 limit gases test gases representative of the extreme variations in the characteristics of the gases for which appliances have been designed [EN 437:2003]
3.4.4 gas pressure static pressure, relative to the atmospheric pressure, measured at right angles to the direction of flow of the gas
NOTE Test pressures are expressed in mbar or bar
3.4.5 test pressure gas pressures used to verify the operational characteristics of appliances using combustible gases They consist of normal and limit pressures
NOTE Test pressures are expressed in mbar (1 mbar = 10 2 Pa) [EN 437:2003]
3.4.6 normal pressure p n pressure under which the appliances operate in nominal conditions when they are supplied with the corresponding reference gas [EN 437:2003]
(maximum limit pressure p max and minimum limit pressure p min)
NOTE Pressures representative of the extreme variations in the appliance supply conditions [EN 437:2003]
A pressure couple refers to the combination of two different gas distribution pressures resulting from a notable disparity in Wobbe indices within a specific family or group of gases In this context, the higher pressure is associated with gases that have a low Wobbe index, while the lower pressure is linked to gases with a high Wobbe index, as defined by EN 437:2003.
3.4.9 relative density d ratio of the masses of equal volumes of dry gas and dry air under the same conditions of temperature and pressure
The calorific value refers to the amount of heat generated by the complete combustion of a unit volume or mass of gas at a constant pressure of 1,013.25 mbar This measurement is based on the combustible mixture's constituents under reference conditions, with the combustion products also returned to the same conditions.
The gross calorific value (H_s) refers to the total energy released when combustion occurs, assuming the water produced is condensed, while the net calorific value (H_i) accounts for the water remaining in vapor form during combustion.
NOTE 2 The calorific value is expressed either in MJ/m 3 of dry gas at the reference conditions or in MJ/kg of dry gas [EN 437:2003]
The Wobbe index, which includes the gross Wobbe index (Ws) and the net Wobbe index (Wi), is defined as the ratio of a gas's calorific value per unit volume to the square root of its relative density, measured under identical reference conditions.
NOTE 1 The Wobbe index is said to be gross or net according to whether the calorific value used is the gross or net calorific value
NOTE 2 The Wobbe index is expressed either in MJ/m 3 of dry gas at the reference conditions or in MJ/kg of dry gas [EN 437:2003].
Conditions of operation and measurement
3.5.1.2 For gas and air volumes dry, brought to 15 °C and to an absolute pressure of 1 013,25 mbar
3.5.2 cold condition condition of the appliance required for some tests and obtained by allowing the unlit appliance to attain thermal equilibrium at room temperature
In hot conditions, the appliance must reach thermal equilibrium at the nominal heat input specified by the manufacturer, with any thermostat remaining fully open for certain tests.
3.5.4 equivalent resistance resistance to flow (in mbar) measured at the outlet of the appliance, which is equivalent to that of the actual flue
Marking of the appliance and packaging
3.6.1 direct country of destination country for which the appliance has been certified and which is specified by the manufacturer as the intended country of destination
At the time of market introduction or installation, the appliance must operate efficiently with one of the gases available in the respective country, without requiring any adjustments or modifications, and at the correct supply pressure.
NOTE 2 More than one country can be specified if the appliance, in its current state of adjustment, can be used in each of these countries
3.6.2 indirect country of destination country for which the appliance has been certified, but for which, in its present state of adjustment, it is not suitable
NOTE Subsequent modification or adjustment is essential in order that it can be utilized safely and correctly in this country
Classification of gases
Gases are categorized into three families, which can be further divided into groups based on the Wobbe index value Table 1 outlines the families and groups of gas referenced in this standard.
Gas family Gas Group Gross Wobbe index
Classification of appliance
4.2.1 Classification according to the gases capable of being used
Appliances of Category I are designed exclusively for the use of gases of a single family or of a single group a) Appliances designed for use on first family gases only
1) Category I 1a : Appliances using only gases of Group a of the first family at the prescribed pressure (this category is not used) b) Appliances designed for use on second family gases only
1) Category I 2H : Appliances using only gases of Group H of the second family at the prescribed supply pressures
2) Category I 2L : Appliances using only gases of Group L of the second family at the prescribed pressures
3) Category I 2E : Appliances using only gases of Group E of the second family at the prescribed pressures
Category I 2+ appliances utilize only gases from Group E of the second family and function with a pressure couple that does not require adjustment within the system If present, the gas regulator of the appliance is inactive within the two standard pressure ranges of the pressure couple.
Appliances designed for use with third family gases, specifically propane and butane, are categorized as follows: Category I 3B/P includes appliances that operate at the specified supply pressure for these gases Category I 3+ encompasses appliances that can utilize both propane and butane without requiring adjustments, except for a possible primary air adjustment for gas type switching, and prohibits the use of operational pressure regulating devices Lastly, Category I 3P refers to appliances that exclusively use propane at the designated supply pressure.
Appliances of Category II are designed for use on gases of two families
4.2.1.2.1 Appliances designed for use on gases of the first and second families
Category II 1a2H appliances are designed to utilize gases from Group a of the first family and gases from Group H of the second family The first family gases are employed under conditions similar to those for Category I1a, while the second family gases are used under conditions akin to those for Category I2H.
Appliances designed for gases of the second and third families include several categories Category II 2H3B/P appliances can utilize Group H gases from the second family and third family gases, operating under the same conditions as Category I 2H and I3B/P, respectively Similarly, Category II 2H3+ appliances are also capable of using these gases, adhering to the same operational conditions as Category I2H and I3+ Lastly, Category II 2H3P appliances are designed for Group H gases from the second family and third family gases, ensuring compatibility and safety in their usage.
The third family gases are utilized under the same conditions as Category I3P, while the second family gases are employed similarly to Category I2H Additionally, appliances classified as Category II 2L3B/P can operate using gases from Group L of the second family and third family gases, adhering to the same conditions as Category I2L and I3B/P, respectively Furthermore, Category II 2L3P appliances are designed to use gases from Group L of the second family.
The third family gases are utilized under the same conditions as Category I3P, while the second family gases are employed similarly to Category I2L Appliances classified as Category II 2E3B/P can operate using gases from Group E of the second family and third family gases, adhering to the same conditions as Category I2E for the second family and Category I3B/P for the third family Additionally, Category II 2E+3+ appliances are designed for gases from Group E of the second family and third family gases, following the same usage conditions as Category I2E+ for the second family and Category I3+ for the third family Lastly, Category II 2E+3P appliances are also capable of using gases from Group E of the second family and third family gases.
The third family gases are utilized under the same conditions as those for Category I3P, while the second family gases are employed similarly to Category I2E+.
Category III appliances are designed for use on the three families
This category is not in general use
Category III appliances admitted in certain countries are given in A.3
4.2.2 Classification according to the mode of evacuation of the combustion products
Appliances are classified into several types according to the method of evacuation of the combustion products and admission of the combustion air
This standard categorizes appliances into four types: Type A, which is not designed for flue connection or external combustion product evacuation; Type A1, a Type A appliance without a fan; Type A2, a Type A appliance featuring a fan located downstream of the combustion chamber; and Type A3, a Type A appliance with a fan positioned upstream of the combustion chamber.
General
When converting gases between different groups or families, or adjusting to varying gas distribution pressures, only specific operations are permitted for each category of appliance.
It is recommended that these operations should be possible without disconnecting the appliance
Category I appliances are classified into several subcategories based on modification requirements For Category I 2H, I 2L, I 2E, and I 2E+, no modifications are needed Similarly, Category I 3B/P also requires no changes to the appliance In the case of Category I 3+, injectors or calibrated orifices may be replaced solely to switch between different pressure couples, such as from 28-30 mbar/37 mbar to 50 mbar/67 mbar, and adjustments to primary air are allowed for switching between butane and propane Lastly, Category I 3P does not require modifications for gas changes, but injector replacements and gas rate adjustments are necessary for pressure changes.
Appliances designed for use with gases from the first and second families require specific adjustments to ensure optimal performance This includes adjusting the gas rate, which may involve changing the injector, restrictor, or regulator Additionally, the gas rate of the ignition burner(s) can be modified using an adjuster or by replacing the injector or restrictor, and if necessary, the entire ignition burner or its components It may also be necessary to change the automatic shut-off valve(s) and to disable the gas rate adjuster(s) as outlined in section 5.2.2.
The adjustments or component changes are only acceptable when converting from a gas of the 1st family to a gas of the 2nd family or vice versa
Appliances designed for use with gases from the second and third families require specific adjustments to ensure optimal performance This includes adjusting the gas rate, which may involve changing the injector, restrictor, or regulator Additionally, the gas rate of the ignition burner(s) must be adjusted, potentially necessitating a change of the injector or restrictor, or even replacing the ignition burner(s) or its parts It may also be necessary to change the automatic shut-off valve(s) and to take the regulator out of service as per the guidelines in section 5.2.6 Furthermore, the gas rate adjuster(s) should be put out of service following the conditions outlined in section 5.2.2.
Adjustments or changes to components are permissible when converting between gases of different families, specifically from a gas of the 2nd family to a gas of the 3rd family and vice versa Additionally, such modifications are acceptable when switching between different butane/propane pressure couples, for example, from 28-30 mbar/37 mbar to 50 mbar/67 mbar and vice versa.
Category III appliances that are permitted in certain countries are given in A.3.3 and A.3.4
5.1.2 Materials and method of construction
The materials' quality and thickness in appliance construction, along with the assembly method of its components, must ensure that both constructional and performance characteristics remain stable throughout a reasonable lifespan and under standard installation and usage conditions.
When properly installed, all components of the appliance must endure the mechanical, chemical, and thermal conditions encountered during normal operation.
Copper shall not be used for gas-carrying parts where its temperature is likely to exceed 100 °C
Asbestos or materials containing asbestos shall not be used
Solder that has a melting point below 450 °C after application shall not be used for gas-carrying parts
5.1.3 Accessibility for maintenance and use
Removable parts for maintenance or cleaning must be easily accessible and designed for straightforward assembly, ensuring correct installation while preventing incorrect assembly It is essential that these components cannot be assembled incorrectly in a way that could lead to hazardous conditions or damage to the appliance and its controls.
It shall be possible to clean the parts in contact with combustion products without using special tools unless these are supplied as necessary accessories with the appliance
All components necessary for the normal operation of the appliance, such as handles and buttons, must be easily accessible without the need to remove any part of the casing Access can be achieved through the opening of a door or access panel.
Constructional parts accessible during use and maintenance shall be free from sharp edges and corners that might cause damage or personal injury during use or maintenance
For appliances installed more than 1.8 meters above floor level, panels that are typically removed for servicing must have a retention mechanism This requirement is fulfilled if appropriate hinges are installed.
Effective thermal insulation must maintain its insulating properties despite exposure to heat and aging It should endure the thermal and mechanical stresses typical in regular use Additionally, the insulation must be non-combustible, securely installed, and safeguarded against mechanical damage, condensation, and pest infestations.
The appliance gas connection shall be accessible
Ensure sufficient clearance around the connection, allowing for easy access to the necessary tools for making the connection All connections should be achievable using commercially available tools.
If the appliance has a threaded connection, this thread shall comply with the requirements of
According to EN ISO 228-1:2003, EN 10226-1:2004, and EN 10226-2:2005 standards, when using threads that meet the requirements of EN ISO 228-1:2003, the end of the appliance inlet connection must be adequately flat to facilitate the use of a sealing washer.
Flanges must adhere to the standards set by ISO 7005-1:1992, ISO 7005-2:1988, or ISO 7005-3:1988, depending on the specific application Additionally, the manufacturer is responsible for supplying the counterflanges and sealing gaskets For information on the connection conditions in different countries, refer to section A.6.
5.1.6 Soundness of the gas circuit
Screw and stud holes for part assembly must not connect to gasways, and there should be a minimum wall thickness of 1 mm between these openings and the gasways However, this regulation does not apply to orifices designed for measurement purposes.
Adjusting, control and safety devices
All devices mentioned in sections 5.2.2.1, 5.2.2.2, and 5.2.2.3, as well as the multifunctional control units they may be integrated into, must be designed for easy removal or replacement to facilitate cleaning or device exchange Additionally, the adjusters for these devices are not interchangeable.
When there are several control knobs (e.g taps and thermostats), they shall not be interchangeable if this could lead to confusion
Gas-carrying controls shall be sited externally to the air duct so as to prevent ingress of gas into the appliance air stream
Gas-carrying connections must be housed in a separate compartment that is properly ventilated This ventilation should be achieved through equally sized openings located near both the top and bottom of the compartment.
The ventilation openings shall have a total free open area equal to, or greater than, 2 % of the area of the largest plane surface of the compartment
The ventilation openings shall be so sited that they cannot be obstructed by foreign matter (e.g birds)
The functioning of any safety device shall not be overruled by that of any control device
5.2.2 Gas rate adjusters and range-rating devices
Gas rate adjusters and range-rating devices must be designed to prevent accidental maladjustment by installers or users after installation and service initiation They should be sealable, such as with paint, post-adjustment The sealing material must withstand the temperature conditions encountered during the appliance's normal operation.
The adjusting screws of gas rate adjusters and range-rating devices shall be located so that they cannot fall into the gasways
The soundness of the gas circuit shall not be affected by the presence of gas rate adjusters and range-rating devices
Appliances in categories I2H, I2L, I2E, I2E+, I3B/P, I3P, II2H3B/P, II2H3+, II2H3P, II2L3B/P, II2E3B/P, II2E+3+ and II2E+3P shall not be fitted with gas rate adjusters However, regulated appliances in all of these categories except category
II2E+3+may have a gas rate adjuster consisting of an adjusting screw on the gas regulator
Appliances in category II1a2H shall have a gas rate adjuster for the 1st family gases
Appliances categorized as II2H3+ and II2E+3+ equipped with a gas rate adjuster can be rendered inoperable when using 3rd family gas This provision also extends to category II1a2H appliances when supplied with 2nd family gas Additionally, for appliances in category II2E+3P with a gas rate adjuster, it is permissible to fully or partially disable these devices when they are supplied with 2nd family gas.
The adjusters shall be capable of adjustment only with the use of a tool and they shall be capable of being set in the operating position
The instructions for conversion to different gases shall specify that all sealing of devices shall be restored after the gas conversion operation
A range-rating device on an appliance is optional
For category II1a2H appliances, the gas rate adjuster and range-rating device can be combined However, if the gas rate adjuster must be sealed when using a 2nd family gas, the installer cannot use the sealed part as a range-rating device.
In cases where a profile plate is installed, the air proving device(s) specified in section 5.4 must trigger a safety shut-down if the air flow across the burner, as specified by the manufacturer, is not met.
Where an adjustable profile plate is used, it shall be capable of being locked in position to avoid inadvertent movement
Any means of adjusting the primary aeration shall be preset and sealed by the manufacturer to discourage unauthorized interference
Manual valves, push buttons, or electrical switches are crucial for the proper operation and commissioning of appliances These components should either be included with the appliance or clearly outlined in the manufacturer's installation instructions if they are not integral to the appliance.
Manual isolation valves shall be of the 90° turn type
Manual isolation valves must be designed and positioned to prevent accidental operation while ensuring ease of use when needed Their design should allow for clear differentiation between the "OPEN" and "CLOSED" positions during operation.
A manual isolating valve integrated into the appliance must operate at a pressure of 1.5 times the maximum supply pressure and should be easily accessible.
Manual isolation valves used solely for OPEN/CLOSED operation shall be provided with positive stops at the
Regulators shall comply with the requirements of EN 88-1:2007
For appliances using 1st or 2nd family gases, the gas supply to the burner and ignition burner must be regulated by an integral regulator located upstream of the automatic shut-off valves, unless it is part of a multifunctional control system.
For an appliance burning 3rd family gases, the fitting of a regulator is optional
For appliances categorized as I2E+ and I2E+3+, the gas regulator must not function within the normal pressure range of the second family pressure couple, specifically between 20 mbar and 25 mbar Similarly, for appliances in the II2E+3+ and II2E+3P categories, it is essential that the regulator can be partially disabled when supplied with second family gases, ensuring it remains non-operational within the same pressure range of 20 mbar to 25 mbar.
The regulator's design must ensure easy adjustment or deactivation for compatibility with different gases, while implementing measures to prevent unauthorized modifications to its settings.
Automatic shut-off valves shall comply with the requirements of EN 161:2007
Multifunctional valves shall comply with the requirements of EN 126:2004
Each primary gas supply must be equipped with two automatic shut-off valves arranged in series One of these valves should have Class A capability, while the other must meet at least Class B standards.
The establishment of the main flame requires a start gas flame, which must be controlled by either: a) a downstream main gas automatic shut-off valve that includes a start gas rate control and a mechanism to limit the energy during ignition to specified values; or b) two automatic shut-off valves, with at least one meeting Class A capability standards.
The downstream main gas automatic shut-off valve with a start gas rate control must not allow the start gas rate to exceed 50% of the fully open flow rate at the same differential pressure.
Ignition devices
The appliance must be operable from an easily accessible location using a switch Additionally, ignition burners and devices, along with their mountings, should be designed to ensure they can only be securely and correctly positioned in relation to the components and burners they are intended to work with.
5.3.2 Ignition device for the main burner
The main burner shall be fitted with an ignition burner or an ignition device for direct ignition
Different ignition burners for various gases must be clearly marked, easily interchangeable, and simple to install This also applies to injectors, which should be replaceable without difficulty Additionally, injectors must feature a permanent identification method and should only be removable using standard commercially available tools.
Ignition burners shall be protected against blockage by gas-borne particulate matter (see 5.2.9).
Combustion and dilution air, pre-purge and post-purge
The appliance shall be fitted with a device(s) for proving adequate combustion and dilution air flow during pre-purge, ignition and operation
Where separate fans provide combustion and/or dilution air an air proving device for each fan shall be fitted
Air flow failure at any time during the pre-purge, ignition or operation of the appliance shall cause safety shut-down or non-volatile lock-out
If safety shut-down occurs there shall be a maximum of 5 automatic re-start attempts after which non-volatile lock-out shall occur
Before starting up, the air proving device(s) must be verified in a "no air" condition; failure to do so will result in a non-volatile lock-out Adequate air flow can be confirmed through differential pressure sensing, which ensures reliable proof of air flow during pre-purge, ignition, and operation, or through flow sensing methods.
Where the setting of the air proving device is not essential to the commissioning of the appliance, the device shall be pre-set by the manufacturer and factory sealed
The correct setting of the air proving device is crucial for the successful commissioning of the appliance Therefore, the commissioning instructions must include detailed information on how to properly set the device, as well as the methods for sealing or locking it in place after adjustment.
Any means of locking or sealing the set position of the air proving device shall be such as to ensure that unauthorized interference cannot occur, or is evident
Before igniting or opening gas shut-off valves, it is essential to purge the appliance The pre-purge duration must be at least 20 seconds at full air flow or proportionally longer at reduced air rates, or it should involve a minimum of five volume changes within the appliance and its ductwork.
NOTE For the purposes of this requirement "ductwork" is taken to be a length of ducting equal to three times the major dimension of the appliance outlet connection
The flame safeguard safe-start check shall continue throughout the pre-purge period
The purge air must be maintained at the specified rate throughout the pre-purge period If the air flow drops below this rate, the burner will either enter a non-volatile lock-out or a safety shut-down Alternatively, the purge process may continue if the required air rate is restored, as long as the air flow remains above 25% of the full rate and the total purge time at the required air rate is preserved.
Flame supervision system
The burner shall be fitted with a flame supervision system
The flame supervision system shall be so designed or arranged that it cannot detect the ignition source as a false flame signal
The flame supervision system must include a safety shut-down mechanism or a non-volatile lock-out feature that activates if the flame detector indicates the presence of a flame at any point during the pre-purge phase.
If the duration of the safe-start check is less than 5 s, detection of a flame or flame simulating condition during the pre-purge shall cause non-volatile lock-out
If the safe-start check exceeds 5 seconds, any detection of a flame or flame-simulating condition during the pre-purge phase will trigger a safety shutdown or a non-volatile lockout.
However, if a flame-simulating condition lasts for 5 s or more, non-volatile lock-out shall occur
NOTE Care should be taken to prevent electrical interference from giving rise to flame detection signals that falsely indicate the presence of a flame
In the event of a flame failure, the flame supervision system will initiate a non-volatile lock-out, preventing any automatic re-ignition attempts through spark restoration or recycling A restart cycle can only be initiated after a manual reset is performed.
The time for the flame supervision system to de-energize the burner automatic safety shut-off valves upon flame failure shall be not more than 1 s
In a self-checking flame supervision system, the safety shut-off valves must de-energize within 1 second during normal operation and within 2 seconds when a simultaneous check is performed.
Start-gas flame establishment
Where the main flame establishment is by means of a start gas flame, the start gas rate shall not exceed
180 kW The start gas flame shall be established either at the main burner or at a separate burner
The first safety time shall be not more than 5 s and preferably should not be less than 2 s
There shall be a start gas flame proving period, the duration of which shall be specified by the manufacturer
The ignition spark must remain inactive until the pre-purge period is fully completed and should be turned off at or before the conclusion of the initial safety time.
The start-gas automatic shut-off valve(s) shall not be energized before the ignition spark (or other means of ignition) is energized
The start-gas flame proving period is crucial for confirming the stability of the flame If the flame is unstable and fails during this period, it will trigger a safety shut-down and a non-volatile lock-out.
To ensure safety during the initial ignition phase, the energy released must be controlled to prevent any explosive pressure increase from causing damage to the appliance or its ducting This safety requirement is met if the start gas rate does not exceed 20% of the stoichiometric gas rate for the verified airflow in the combustion chamber for 1st and 3rd family gases, and 33% of the stoichiometric gas rate for 2nd family gases.
For appliances with a heat input rating of 180 kW or higher, it is essential to implement measures that guarantee the downstream main gas shut-off valve is closed before the start-up, especially when the gas supply is sourced between the main gas automatic shut-off valves.
NOTE 1 A valve proving system or a proof of closure switch is deemed to satisfy this requirement
If the valve is not proved to be closed start-up shall be prevented
For appliances with a heat input rating below 180 kW, it is essential to ensure safety during gas supply start-up A mechanism must be in place to confirm the closure of the downstream main gas shut-off valve; if this closure cannot be verified, the start-up process must be halted Additionally, ignition at the full main gas rate must not create a hazardous situation, as outlined in section 7.3.4.4 It is important to note that a valve proving system or a proof of closure switch meets the necessary safety requirements.
The start gas rate is regulated by a position within the downstream main gas automatic shut-off valve, which must adhere to EN 161:2002 standards Furthermore, any adjustments to the start gas rate or the operating position of an interlock, if present, should be pre-set and sealed by the manufacturer.
For appliances with a heat input of 180 kW or more, it is essential that the interlock controlling the start gas valve is verified to be in the correct state during both the initial safety time and the start gas flame proving period.
If the interlock shows that the start gas rate has been surpassed, the valve must de-energize within 1 second, leading the appliance to enter a non-volatile lock-out state.
The start gas rate is regulated by a position within the downstream main gas automatic shut-off valve In the absence of an interlock for controlling this position, it is essential to confirm that igniting the ignition burner, under the specified test conditions in section 7.3.4.4, does not create a hazardous situation.
Main flame establishment
5.7.1 Establishment by means of a start gas flame
The main gas automatic shut-off valves shall not be energized to admit the main gas flow to the burner until after the start gas flame has been proved
The main flame shall ignite reliably and smoothly from the start gas flame
Once the start gas flame is ignited and confirmed at a separate ignition burner, the second safety time must be between 2 to 5 seconds After this period, the ignition burner flame will be extinguished, and monitoring will shift solely to the main flame If the main flame is not detected within this timeframe, a safety shut-down and non-volatile lock-out will occur.
In systems where a separate ignition burner flame operates alongside the main burner, dedicated flame detectors are installed to monitor both flames It is crucial that the main flame detector is positioned to avoid detecting the ignition burner flame Furthermore, the safe-start check mandated by section 5.5 must be performed on the main flame detector during the initial safety time and the gas proving period.
To ensure reliable ignition of the main flame, the flame detector must only detect the start gas flame at specific gas flow rates that allow for smooth and consistent lighting It is essential to consider factors such as flame reduction, detector drift, maladjustment, gas pressure fluctuations, and dimensional stability in the operation of the ignition system.
Direct ignition of the main flame is permitted solely for appliances with heat inputs under 180 kW, provided that the gas rate during ignition does not surpass 20% of the stoichiometric gas rate for 1st and 3rd family gases, or 33% for 2nd family gases, based on the verified air flow rate through the combustion chamber.
For the main burner, it is crucial that the ignition source remains de-energized until the pre-purge period is complete, and the gas valves should only be energized after the ignition source is activated In systems utilizing hot surface ignition, the ignition must be activated to ensure it can ignite the gas prior to opening the gas valves Additionally, the first safety time must be set between 2 to 5 seconds, after which the ignition source should be de-energized If the flame is not detected within this timeframe, a non-volatile lock-out will occur.
Main burner
The cross-sectional area of the flame ports shall not be adjustable
All injectors and removable restrictors must have a permanent identification method They should be changeable without relocating the appliance from its installed position, but injectors can only be removed using standard commercial tools.
The burner shall be so located and arranged that misalignment cannot occur It shall not be possible to remove the burner assembly without the use of tools.
Facility for remote control
When an appliance can be controlled remotely, such as through thermostats or timers, the electrical connection for these controls must be established without interfering with any internal connections, except for a designated link specifically intended for this purpose.
Thermostats and control of air temperature
Integral mechanical thermostats shall comply with the requirements of EN 257:1992
Electrical thermostats shall comply with the requirements of EN 60730-2-1:1997
Overheat cut-off devices shall be of Type 2K and comply with the requirements of EN 60730-2-9:2002
The appliance shall be provided, either integral with the appliance or separately, with a device to control the temperature of the delivered air
If the air temperature control is not built into the appliance, it must be provided by the manufacturer, and the installation instructions should include specific details for its installation.
Proper installation of the appliance according to the manufacturer's guidelines ensures that no hazardous conditions or damage will arise from a failure in air temperature control.
An overheat cut-off device must be installed in the appliance to ensure shut-down and non-volatile lock-out during an overheat condition This lock-out mechanism should operate independently of the flame detection circuits, and specifically, the overheat cut-off device must not be connected in series with the flame sensor.
Mechanical control thermostats and overheat cut-off devices can share the same sensor, and if this sensor fails, it may lead to a non-volatile lock-out of the appliance.
With an electronic system, thermostats and overheat cut-off devices shall not have the same sensor unless it is break-safe.
Gas pressure points
The appliance must include a minimum of two gas pressure test points: one located upstream of the initial control and safety device, and the other positioned downstream of the final gas flow rate control These test points should be strategically placed to facilitate accurate measurements.
The test points shall have an external diameter of
The bore diameter must not exceed 1.0 mm at its minimum cross-section, and the tube should have a useful length of at least 10 mm to ensure proper fitting.
Facilities for commissioning and testing
To facilitate commissioning, permanent means shall be provided to prevent gas flowing at rates other than the start gas flow rate
To meet the requirement, one can use: a manual valve located downstream of the main gas automatic shut-off valve; a removable air-break electrical link that does not involve disconnecting the electrical wiring to the main gas automatic shut-off valves; an air-break switch that necessitates a tool for operation to isolate the electrical supply; or an air-break switch that operates without the need for a tool to isolate the electrical supply to the main gas automatic shut-off valves.
In cases where the main gas valve(s) are equipped with a closed position indicator switch or a proof of closure switch, it is essential to verify the switch's correct position during the initial safety time and throughout the main gas isolation period Any failure to confirm proper positioning will result in a safety shut-down Additionally, a multifunctional control that includes the necessary features is considered compliant with this requirement.
NOTE 2 Additional circuitry over and above that provided by the control box may be necessary to satisfy requirement d)
Designers must understand that this requirement aims to ensure the main gas supply remains securely contained while the commissioning engineer is either setting or verifying the start gas flame.
The appliance shall be provided with such manual valves as are essential for the normal operation and commissioning of the appliance
Means shall be provided for checking the gas soundness of automatic shut-off valves
Means shall be provided for checking the regulator inlet and outlet pressures and the burner manifold pressure
Connections or test points shall be provided for the measurement of the flame detector signal
Test points shall be provided to facilitate the measurement of differential air pressure across the burner and/or profile plate.
Additional requirements for appliances designed for permanent outdoor installation
Appliances designed for permanent outdoor installation shall be so constructed that they are fully protected against the rigours of the environmental conditions under which they are expected to operate
Air inlets must be installed with their lowest edge at least 500 mm above the appliance base or positioned to reach 500 mm above floor level, following the manufacturer's guidelines.
Access panels and doors, along with any insulation that must be removed for routine maintenance, should be engineered to ensure that repeated removal and reinstallation does not compromise the insulation or the waterproof integrity of the appliance.
Any opening in the appliance, such as electrical wiring points, must be designed to prevent the entry of a ball with a diameter of 16 mm when a force of 5 N is applied.
External panels designed for maintenance and servicing must be secured with hexagon-headed screws However, user access panels can be attached using hinges and door catches.
Soundness of the gas circuit
The gas circuit shall be sound
External soundness is assured if, under the conditions specified in 7.3.1, the air leakage rate does not exceed
100 cm 3 /h regardless of the number of valves fitted in series or in parallel on the appliance.
Heat inputs
When measured under the conditions specified in 7.3.2.2, the heat input obtained at normal pressure shall be within ± 5 % of the nominal heat input
Under the conditions outlined in section 7.3.2.3, the start gas heat input at normal pressure must be within ± 5% of the manufacturer's declared start gas heat input for injectors with a diameter greater than 0.5 mm.
Where the injector diameter is 0,5 mm or less the start gas heat input shall be within ±10 % of the manufacturer's declared value
6.2.3 Effectiveness of gas rate adjusters
For appliances lacking a gas regulator but equipped with a gas rate adjuster, the adjusted heat input must meet specific criteria: it should be no less than the nominal heat input as specified in Test 1 of section 7.3.2.4, and it must not exceed the nominal heat input according to the conditions outlined in Test 2 of section 7.3.2.4.
6.2.4 Effectiveness of the gas regulator
For appliances equipped with an adjustable gas regulator, the allowable variation in gas flow rates must not exceed +7.5% and -10% for 1st family gases, and ±5% for 2nd and 3rd family gases This variation is based on the rate determined at the specified adjustment pressure, while the upstream pressure fluctuates between the minimum and maximum values outlined for the relevant appliance category.
6.2.5 Effectiveness of the range-rating device
For appliances equipped with a range-rating device, the nominal heat input must be achieved within ± 5% of the manufacturer's stated nominal heat input at maximum rate, and the minimum heat input must also be within ± 5% of the manufacturer's specified minimum heat input at minimum rate, as outlined in section 7.3.2.6.
For category I2L and I2H appliances equipped with a gas rate adjuster that is not separate from the range-rating device, the manufacturer's specified heat input range must be achieved within a tolerance of ± 5%.