Automatic forced draught burners for gaseous fuels

This European Standard specifies the terminology, the general requirements for the construction and operation of automatic forced draught gas burners and also the provision of control and safety devices, and the type test procedure for these burners.
This standard is applicable to
¾ automatic gas burners with a combustion air fan (hereinafter called "burners") that are equipped as described in clause 4, intended for use in heat generators of different types, and that are operated with fuel gases;
¾ total pre-mixed burners and nozzle mixed burners.
The standard is applicable to
¾ single burners with a single combustion chamber, although such burners are fitted to a single appliance, in which case the requirements of the relevant appliance standard shall additionally apply;
¾ single-fuel and dual-fuel burners when operating only on gas;
¾ the gas function of dual-fuel burners designed to operate simultaneously on gaseous and liquid fuels in which case the requirements of EN 267 will also apply in respect of the liquid fuel function.

Automatische Brenner mit Gebläse für gasförmige Brennstoffe

Diese Norm legt die Begriffe, die allgemeinen Anforderungen für den Bau und die Funktion von automatischen Gasbrennern mit Gebläse sowie die Ausrüstung mit Regel- und Sicherheitseinrichtungen und das Verfahren für die Typprüfung dieser Brenner fest.
Diese Norm gilt für
¾ automatische Gasbrenner mit Verbrennungsluft-Gebläse (im Folgenden Brenner genannt), die nach Abschnitt 4 ausgerüstet sind und deren Verwendung in Wärmeerzeugern verschiedener Art behandelt wird und die mit technischen Brenngasen betrieben werden;
¾ Vormischbrenner und Düsenbrenner.
Diese Norm gilt für
¾ Einzelbrenner mit nur einem einzigen Feuerraum, aber auch solche, die mit Geräten zusammengebaut werden; in diesem Fall gelten die zusätzlichen Geräteanforderungen;
¾ Brenner und Zweistoffbrenner für den ausschließlichen Betrieb mit Gas;
¾ auch den Betrieb mit Gas von Zweistoffbrennern, die gleichzeitig mit gasförmigen oder flüssigen Brenn-stoffen betrieben werden. In diesem Fall gelten auch die Anforderungen von EN 267 für den Betrieb mit flüssigen Brennstoffen.

Brûleurs automatiques à air soufflé pour combustibles gazeux

La présente Norme européenne prescrit la terminologie, les exigences générales concernant la construction et le fonctionnement des brûleurs automatiques à gaz à air soufflé, leur équipement avec des dispositifs de régulation et de sécurité et les méthodes d'essais de type pour ces brûleurs.
La présente Norme européenne est applicable :
   aux brûleurs automatiques à gaz avec ventilateur d'air de combustion (dénommés ci après " brûleurs ") équipés comme indiqué à l'article 4, destinés à être utilisés sur des générateurs de chaleur de différents types et qui fonctionnent avec des combustibles gazeux ;
   aux brûleurs à pré-mélange total et aux brûleurs à mélange au nez.
La présente Norme européenne est aussi applicable :
   aux brûleurs individuels, alimentant une seule chambre de combustion, installés sur un seul appareil, auquel cas les exigences de la norme concernant l'appareil s'appliquent de façon additionnelle ;
   aux brûleurs mono et bi combustible pour leur fonctionnement exclusif au gaz ;
   au fonctionnement au gaz des brûleurs bi-combustibles conçus pour fonctionner simultanément aux combustibles liquides et gazeux; dans ce cas, les exigences de l'EN 267 s'appliquent pour le fonctionnement aux combustibles liquides.

Samodejni plinski ventilatorski gorilniki

General Information

Status
Withdrawn
Publication Date
05-Aug-2003
Withdrawal Date
10-Jun-2008
Current Stage
9960 - Withdrawal effective - Withdrawal
Start Date
11-Jun-2008
Completion Date
11-Jun-2008

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SLOVENSKI STANDARD
SIST EN 676:2004
01-januar-2004
1DGRPHãþD
SIST EN 676:1997
Samodejni plinski ventilatorski gorilniki
Automatic forced draught burners for gaseous fuels
Automatische Brenner mit Gebläse für gasförmige Brennstoffe
Bruleurs automatiques a air soufflé pour combustibles gazeux
Ta slovenski standard je istoveten z: EN 676:2003
ICS:
27.060.20
SIST EN 676:2004 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN 676
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2003
ICS 27.060.20 Supersedes EN 676:1996
English version
Automatic forced draught burners for gaseous fuels

Brûleurs automatiques à air soufflé pour combustibles Automatische Brenner mit Gebläse für gasförmige

gazeux Brennstoffe
This European Standard was approved by CEN on 3 April 2003.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official

versions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 676:2003 E

worldwide for CEN national Members.
---------------------- Page: 2 ----------------------
EN 676:2003 (E)
Contents

1 Scope ..............................................................................................................................................................6

2 Normative references ....................................................................................................................................6

3 General definitions ........................................................................................................................................7

3.1 Specific definitions ........................................................................................................................................8

4 Constructional and operational requirement............................................................................................14

4.1 Conversion to different gases ....................................................................................................................14

4.2 Construction.................................................................................................................................................14

4.3 Equipment.....................................................................................................................................................15

4.4 Functional and operational requirements .................................................................................................21

5 Test methods................................................................................................................................................29

5.1 General..........................................................................................................................................................29

5.2 Functional tests............................................................................................................................................33

5.3 Operation ......................................................................................................................................................34

5.4 Tests to be carried out on the working and test diagrams......................................................................35

5.5 Combustion ..................................................................................................................................................38

5.6 Start-up .........................................................................................................................................................39

5.7 Obtaining the heat input..............................................................................................................................39

5.8 Electrical safety............................................................................................................................................40

6 Marking, labelling and packaging ..............................................................................................................40

6.1 General..........................................................................................................................................................40

6.2 Data plate......................................................................................................................................................40

6.3 Other marking...............................................................................................................................................41

6.4 Instructions for installation, adjustment, maintenance and operation ..................................................41

6.5 Marking on the packaging...........................................................................................................................42

6.6 Official languages to be used.....................................................................................................................42

Annex A (informative) Determination of the combustion characteristics - carbon monoxide and

nitrogen oxides ............................................................................................................................................55

Annex B (informative) Examples of control box sequencing ...............................................................................57

Annex C (informative) Test gases............................................................................................................................58

C.1 General..........................................................................................................................................................58

C.2 Conditions for preparation of the test gases............................................................................................58

C.3 Practical application of the test gases ......................................................................................................59

Annex D (informative) Gas connections conditions in common use in the various countries.........................62

Annex E (informative) Tests .....................................................................................................................................63

E.1 Supplementary testing ................................................................................................................................63

E.2 Drawing review.............................................................................................................................................63

E.3 Individual test and inspection ....................................................................................................................63

E.4 Test report ....................................................................................................................................................64

Annex F (informative) Use of alternative gas lines and test documentation ......................................................65

F.1 Use of alternative gas lines.........................................................................................................................65

F.2 Test documentation.....................................................................................................................................65

Annex G (informative) Correction of the influence of combustion air temperature and humidity on NO -

emissions......................................................................................................................................................66

Annex H (informative) Check of the air proving device.........................................................................................67

Annex I (informative) Specific additional requirements and limitations for use of EN 676 burners for

industrial applications.................................................................................................................................68

I.1 Pre-heating of the combustion air..............................................................................................................68

I.2 Continuous working of the air ventilator...................................................................................................68

I.3 Electronic air/fuel ratio and O -controllers................................................................................................68

I.4 Variable excess of combustion air.............................................................................................................68

---------------------- Page: 3 ----------------------
EN 676:2003 (E)

I.5 Burner with start gas flame ........................................................................................................................69

I.6 Air filtering....................................................................................................................................................69

Annex ZA (informative) A-deviations .......................................................................................................................70

Annex ZB (informative) Clauses of this European Standard addressing essential requirements or other

provisions of EU Directives ........................................................................................................................71

---------------------- Page: 4 ----------------------
EN 676:2003 (E)
Foreword

This document EN 676:2003 has been prepared by Technical Committee CEN/TC 131 “Gas burners using fans”,

the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical text or

by endorsement, at the latest by February 2004, and conflicting national standards shall be withdrawn at the latest

by February 2004.

This document has been prepared under a mandate given to CEN by the European Commission and the European

Free Trade Association, and supports essential requirements of EU Directive(s).

For relationship with EU Directive(s), see informative Annex ZB, which is an integral part of this document.

NOTE This European Standard had also been proposed for inclusion in the mandate under the EU Directive 98/37/EC

(Machinery Directive). As the mandate has been given after the Standard had been accepted by the Technical Committee for

submission to Formal Vote and in order not to further delay its publication, it will be reviewed within the context of the Directive

98/37/EC directly after the publication.
According to edition 1996 the following fundamental changes are given:
 revisions for special applications;

 implementation of NO -classes and forming of arithmetic average values for determining the NO -values;

x x
 implementation of appliance categories for forced draught burners.
Annexes A, B, C, D, E, F, G, H, J and ZA are informative.
This document includes a Bibliography.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,

Slovakia, Spain, Sweden, Switzerland and the United Kingdom.
---------------------- Page: 5 ----------------------
EN 676:2003 (E)
Introduction

This European Standard is primarily intended for automatic forced draught gas burners having a combustion air

fan, operated with gaseous fuels, and intended to be marketed as a complete assembly.

EN 437 sets out a system of classification of appliances into categories defined according to the gases and

pressures for which they are designed.

Such a system of classification, when applied to forced draught burners, can lead to difficulties in defining the

precise category to which a particular burner should be allocated. For example many burners are designed to

operate on a wide range of fuel gases with little or no modification other than adjustment of air supply.

The technical committee responsible for the standard decided that the following appliance categories for forced

draught burners should apply:
 single categories: I for natural gas and I for liquefied petroleum gas;
2R 3R
 dual category: II for natural and liquefied petroleum gas.
2R /3R

All the burners of this standard marked with these categories are commissioned on site and the measured values

are recorded in a commissioning report.

However it should be noted that the Gas Appliance Directive requires the specification of the type of gas and the

supply pressure used as well as the burner category.

Forced draught gas burners according to this standard are often used in industrial applications. The safety

principles are the same as for forced draught gas burners used for household/commercial applications. Industrial

forced draught gas burners however should operate safely in their industrial environment and the risks involved can

differ from those for household applications. These industrial forced draught gas burners can be characterized by

the ability to withstand industrial environmental influences, like moisture, high temperature, electrical and magnetic

phenomena, vibrations, etc.

Principal requirements for installation and construction of gas burners and industrial thermal processing are

covered by EN 746-family.

Special requirements for forced draught burners for industrial premises will be given as a note with the addition

"Industrial application".

Further information and application limitation for EN 676 forced draught burners which are used for industrial

application are given in informative annex I
---------------------- Page: 6 ----------------------
EN 676:2003 (E)
1 Scope

This European Standard specifies the terminology, the general requirements for the construction and operation of

automatic forced draught gas burners and also the provision of control and safety devices, and the type test

procedure for these burners.
This standard is applicable to

 automatic gas burners with a combustion air fan (hereinafter called "burners") that are equipped as described

in clause 4, intended for use in heat generators of different types, and that are operated with fuel gases;

 total pre-mixed burners and nozzle mixed burners.
The standard is applicable to

 single burners with a single combustion chamber, although such burners are fitted to a single appliance, in

which case the requirements of the relevant appliance standard shall additionally apply;

 single-fuel and dual-fuel burners when operating only on gas;

 the gas function of dual-fuel burners designed to operate simultaneously on gaseous and liquid fuels in which

case the requirements of EN 267 will also apply in respect of the liquid fuel function.

2 Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications. These

normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For

dated references, subsequent amendments to or revisions of any of these publications apply to this European

Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the

publication referred to applies (including amendments).
EN 88, Pressure governors for gas appliances for inlet pressures up to 200 mbar.
EN 161, Automatic shut-off valves for gas burners and gas appliances.

EN 267, Forced draught oil burners – Definitions, requirements, testing, marking.

EN 298, Automatic gas burner control systems for gas burners and gas burning appliances with or without fans.

EN 334, Gas pressure regulators for inlet pressures up to 100 bar.

EN 1092-1, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN designated

— Part 1: Steel flanges.

EN 1092-2, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN designated

— Part 2: Cast iron flanges.

prEN 1092-3, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN designated

— Part 3: Copper alloy flanges.

EN 1643, Valve proving systems for automatic shut-off valves for gas burners and gas appliances.

EN 1854, Pressure sensing devices for gas burners and gas burning appliances.

EN 10208-1, Steel pipes for pipelines for combustible fluids — Technical delivery conditions — Part 1: Pipes of

requirement class A.

EN 10208-2, Steel pipes for pipelines for combustible fluids — Technical delivery conditions- Part 2: Pipes of

requirement class B.
---------------------- Page: 7 ----------------------
EN 676:2003 (E)

EN 10216-1, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 1: Non-alloy

steel tubes with specified room temperature properties.

EN 10217-1, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 1: Non-alloy steel

tubes with specified room temperature properties.

EN 12067-1, Gas/air ratio controls for gas burners and gas burning appliances — Part 1: Pneumatic types.

prEN 12067-2, Gas/air ratio controls for gas burners and gas burning appliances — Part 2: Electronic types.

prEN 50156-1, Electrical equipment for furnaces and ancillary equipment — Part 1: Requirements for application

design and installation.

EN 60204-1, Safety of machinery — Electrical equipment of machines — Part 1: General requirements (IEC

60204-1:1997).

EN 60335-1:1994, Safety of household and similar electrical appliances — Part 1: General requirements

(IEC 60335-1:1991, modified).

EN 60529, Degrees of protection provided by enclosures (IP code) (IEC 60529:1989).

EN 60947-5-1, Low-voltage switchgear and controlgear — Part 5-1: Control circuit devices and switching elements

— Electromechanical control circuit devices (IEC 60947-5-1:1997).

ENV 10220, Seamless and welded steel tubes — Dimensions and masses per unit length.

prEN ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions,

tolerances and designation (ISO 228-1:2000).

EN ISO 3166-1, Codes for the representation of names of countries and their subdivisions – Part 1: Country codes

(ISO 3166-1:1997).

ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances and

designation.
3 Terms and definitions

For the purposes of this European Standard, the following terms and definitions apply.

3.1 General terms and definitions
3.1.1
forced draught burner
burner in which the total air for combustion is supplied by means of a fan
3.1.2
automatic forced draught burner

burner that is fitted with an automatic ignition, flame monitoring and burner control devices. Ignition, flame

monitoring and the on/off switching of the burner occur automatically. The heat input of the burner can be adjusted

during operation either automatically or manually.
3.1.3
dual-fuel burner

burner in which both gaseous and liquid fuels can be burnt either simultaneously or in succession

3.1.4
total pre-mixed burner

burner in which part, or all, of the air for complete combustion of the gas is mixed with the gas upstream of the

mixture outlet ports
---------------------- Page: 8 ----------------------
EN 676:2003 (E)
3.1.5
nozzle mixed burner

burner in which part, or all, of the air required for combustion of the gas is mixed with the gas at, or downstream of,

the air and gas ports
3.1.6
integrated ignition burner

burner with direct main ignition burner at reduced rate with by-pass start gas supply

3.1.7
start gas rate
gas rate ignited by the ignition device during the start-up of the burner
3.1.8
industrial applications
industrial applications means:
 the extraction,
 growth,
 refining,
 processing,
 production,
 manufacture or
 preparation
of materials, plants, livestock, animal products, food or artefacts.
3.1.9
combustion chamber
part of the appliance in which the combustion takes place
3.2 Specific terms and definitions
3.2.1 Combustible gases
3.2.1.1
reference conditions
these correspond to 15 °C, 1013,25 mbar, unless otherwise specified
3.2.1.2
calorific value

quantity of heat produced by the combustion, at a constant pressure equal to 1013,25 mbar, of unit volume or

mass of gas, the constituents of the combustible mixture being taken at reference conditions and the products of

combustion being brought back to the same conditions
A distinction is made between:

 the gross calorific value: in which the water produced by combustion is assumed to be condensed;

Symbol: H
and

 the net calorific value: in which the water produced by combustion is assumed to be in the vapour state.

Symbol: H
---------------------- Page: 9 ----------------------
EN 676:2003 (E)
Units: either
 megajoules per cubic metre (MJ/m³) of dry gas at the reference conditions, or
 megajoules per kilogram (MJ/kg) of dry gas.
3.2.1.3
relative density

ratio of the masses of equal volumes of dry gas and dry air at the same conditions of temperature and pressure

Symbol: d
3.2.1.4
Wobbe index

ratio of the calorific value of a gas per unit volume and the square root of its relative density under the same

reference conditions. The Wobbe index is said to be gross or net according to whether the calorific value used is

the gross or net calorific value
Symbols: gross Wobbe index: W
net Wobbe index: W
Units: either
 megajoules per cubic metre (MJ/m³) of dry gas at the reference conditions, or
 megajoules per kilogram (MJ/kg) of dry gas.
3.2.1.5
gas pressure

static pressure of the moving gas, relative to the atmospheric pressure, measured at right angles to the direction of

flow of the gas. It is expressed in millibars (mbar) or in bars (bar).
3.2.1.6
reference gases

test gases on which burners operate under nominal conditions when they are supplied at the corresponding normal

pressure
3.2.1.7
limit gases

test gases representative of the extreme variations in the characteristics of the gases for which burners have been

designed

NOTE The characteristics of the reference and limit gases are given in Table C.1.

3.2.1.8
normal pressure

pressure under which the burners operate in nominal conditions when they are supplied with the corresponding

reference gas
3.2.1.9
limit pressures

pressures representative of the extreme variations in the burner supply conditions

NOTE The test pressures are given in Table 5.
3.2.1.10
supply pressure

pressure measured at the measuring point M1 as specified in Figure 1, at which the nominal conditions are

achieved
---------------------- Page: 10 ----------------------
EN 676:2003 (E)
3.2.1.11
adjustment pressure

pressure measured at the measuring point M2 as specified in Figure 1, at which the nominal conditions are

achieved
3.2.1.12
burner head pressure

pressure measured at the measuring point M3 as specified in Figure 1, at which the nominal conditions are

achieved
3.2.1.13
pressure in the combustion chamber

pressure or depression, relative to atmospheric pressure, prevailing in the combustion chamber

3.2.2 Operation of the burner
3.2.2.1 gas rate
3.2.2.1.1
volumetric flow rate
volume of gas consumed by the burner in unit time during continuous operation
3 3

Units: cubic metres per hour (m /h), litres per minute (l/min), cubic decimetres per hour (dm /h) or cubic decimetres

per second (dm /s).
Symbol: V
3.2.2.1.2
nominal volumetric flow rate

volumetric flow rate stated by the manufacturer, expressed in cubic metres per hour (m /h)

3.2.2.1.3
maximum flow rate

highest flow rate stated by the manufacturer, expressed in cubic metres per hour (m /h) at reference conditions

3.2.2.1.4
minimum flow rate

lowest flow rate stated by the manufacturer, expressed in cubic metres per hour (m /h) at reference conditions

3.2.2.1.5
mass flow rate
mass of gas consumed by the burner in unit time during continuous operation
Symbol: M
Units: kilograms per hour (kg/h), or grams per hour (g/h)
3.2.2.1.6
nominal mass flow rate
mass flow rate stated by the manufacturer
3.2.2.1.7
heat input

quantity of energy used in unit time corresponding to the volumetric or mass flow rates, the calorific value used

being either the net or gross calorific value
Symbol: Q
Unit: kilowatt (kW)

Burners with fixed heat input or single stage burners have a single heat input. Range-rated burners have a

maximum heat input and a minimum heat input declared by the manufacturer.
---------------------- Page: 11 ----------------------
EN 676:2003 (E)
3.2.2.1.8
maximum heat input
highest value of the heat input declared by the manufacturer
Symbol: Q
F max
3.2.2.1.9
minimum heat input
lowest value of the heat input declared by the manufacturer
Symbol: Q
F min
3.2.2.2 running conditions
3.2.2.2.1
burners for permanent operation

burners that are designed to remain in the running condition for more than 24 h without interruption

3.2.2.2.2
burners for intermittent operation
burners that are designed to remain in the running condition for less than 24 h
3.2.3 Gas line components
3.2.3.1
gas line

part of the burner which is made up of the valves and controls and safety devices in which gas is conveyed

between the inlet connection and the burner head
3.2.3.2
range-rating device

component on the burner intended to be used for adjusting the heat input, within a range of heat inputs stated by

the manufacturer, to suit the actual heat requirements of the installation
This adjustment can be progressive or in discrete steps.
3.2.3.3
automatic shut-off valve
valve which opens when energised and closes automatically when de-energised
3.2.3.4
filter/strainer

device that enables foreign elements, which might otherwise cause failures in the system, to be collected

3.2.4 Adjusting, control and safety devices
3.2.4.1
pressure governor

device which maintains the downstream pressure constant to within fixed limits independent of variations, within a

given range, of the upstream pressure
3.2.4.2
adjustable pressure governor

pressure governor fitted with a means of adjusting the loading on the diaphragm and thus the downstream

pressure
3.2.4.3
gas pressure protection devices

device which compares the actual value of the pressure with the desired value, gives a signal when the actual

value exceeds or drops below the desired value and initiates the controlled shut-down

---------------------- Page: 12 ----------------------
EN 676:2003 (E)
3.2.4.4
flame detector device
device by which the presence of a flame is detected and signalled

It can consist of a flame sensor, an amplifier and a relay for signal transmission. These parts, with the possible

exception of the actual flame sensor, can be assembled in a single housing for use in conjunction with a

programming unit
3.2.4.5
automatic burner control system

system which comprises at least a programming unit and all the elements of a flame detector device. The various

functions of an automatic burner control system can be in one or more housings.
3.2.4.6
programming unit

unit which reacts to signals from control and safety devices, gives control commands, controls the start-up

sequence, supervises the burner operation and causes controlled shut-down, and if necessary safety shut-down

and non-volatile lock-out. The programming unit follows a predetermined sequence of actions and always operates

in conjunction with a flame detector device.
3.2.4.7
safe start check

procedure employing a protection circuit or circuits, to establish whether or not a fault in a safety system or a flame

simulating condition exists prior to start-up
3.2.4.8
controlled shut-down

process by which the power to the gas shut-off valve(s) is removed before any other action takes place, e. g. as a

result of the action of a controlling function
3.2.4.9
safety shut-down

process which is effected immediately following the response of a safety device or the detection of a fault in the

automatic burner control system and which puts the burner out of operation by immediately removing the power to

the gas shut-off valve(s) and the ignition device

NOTE Safety shut-down can also occur as a result of an interruption/decrease of the power supply.

3.2.4.10
non-volatile lock-out

safety shut-down condition of the system, such that a restart can only be accomplished by a manual reset of the

system and by no other means
3.2.4.11
volatile lock-out

safety shut-down condition of the system, such that a restart can only be accomplished by either the manual reset

of the system, or an interruption of the main power and its subsequent restoration

3.2.4.12
start signal

signal, e. g. from a thermostat, which releases the system from its start position and commences the predetermined

programme
3.2.4.13
recycl
...

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