EN 778:2009

SLOVENSKI STANDARD
01-februar-2010
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SIST EN 778:1999
SIST EN 778:1999/A1:2002
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Domestic gas-fired forced convection air heaters for space heating not exceeding a net
heat input of 70 kW, without a fan to assist transportation of combustion air and/or
combustion products
Gasbefeuerte Warmlufterzeuger mit erzwungener Konvektion zum Beheizen von
Räumen für den häuslichen Gebrauch mit einer Nennwärmebelastung nicht über 70 kW,
ohne Gebläse zur Beförderung der Verbrennungsluft und/oder der Abgase
Générateurs d'air chaud à convection forcée utilisant les combustibles gazeux pour le
chauffage de locaux à usage d'habitation de débit calorifique sur Hi inférieur ou égal à 70
kW, sans ventilateur pour aider l'alimentation en air comburant et/ou l'évacuation des
produits de combustion
Ta slovenski standard je istoveten z: EN 778:2009
ICS:
97.100.20 Plinski grelniki Gas heaters
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 778
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2009
ICS 97.100.20 Supersedes EN 778:1998
English Version
Domestic gas-fired forced convection air heaters for space
heating not exceeding a net heat input of 70 kW, without a fan to
assist transportation of combustion air and/or combustion
products
Générateurs d'air chaud à convection forcée utilisant les Gasbefeuerte Warmlufterzeuger mit erzwungener
combustibles gazeux pour le chauffage de locaux à usage Konvektion zum Beheizen von Räumen für den häuslichen
d'habitation de débit calorifique sur Hi inférieur ou égal à 70 Gebrauch mit einer Nennwärmebelastung nicht über 70
kW, sans ventilateur pour aider l'alimentation en air kW, ohne Gebläse zur Beförderung der Verbrennungsluft
comburant et/ou l'évacuation des produits de combustion und/oder der Abgase
This European Standard was approved by CEN on 12 September 2009.

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 CEN 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 CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 778:2009: E
worldwide for CEN national Members.

Contents Page
Foreword .4
1 Scope .6
2 Normative references .7
3 Terms and definitions .8
3.1 Appliance and its constituent parts .8
3.2 Adjustment, control and safety devices . 10
3.3 Operation of the appliance . 13
3.4 Gases . 15
3.5 Conditions of operation and measurement . 16
3.6 Marking of the appliance and packaging . 17
4 Classification . 17
4.1 Classification of gases . 17
4.2 Classification of appliance . 18
5 Construction and design requirements . 21
5.1 General . 21
5.2 Adjusting, control and safety devices . 27
5.3 Ignition devices . 31
5.4 Flame supervision system . 31
5.5 Start-gas flame establishment . 32
5.6 Main flame establishment . 33
5.7 Main burner . 33
5.8 Facility for remote control . 34
5.9 Thermostats and control of air temperature . 34
5.10 Gas pressure test points . 35
6 Operational requirements . 35
6.1 Safety of operation . 35
6.2 Efficiency . 41
7 Test methods . 42
7.1 General . 42
7.2 Construction and design . 49
7.3 Safety of operation . 50
7.4 Efficiency . 82
8 Marking and instructions . 87
8.1 Marking of the appliance . 87
8.2 Marking of the packaging . 88
8.3 Utilization of symbols on the appliance and packaging . 89
8.4 Instructions . 91
9 Evaluation of POCED conformity and their associated terminals . 93
9.1 General . 93
9.2 Type testing . 93
9.3 Factory production control (FPC) . 93
Annex A (informative) National situations . 96
A.1 General . 96
A.2 Categories listed in the body of the standard and marketed in different countries . 96
A.3 Appliance supply pressures corresponding to the categories given in A.2 . 98
A.4 Special categories marketed nationally or locally . 99
A.5 Test gases corresponding to the special categories given in A.4 . 105
A.6 Gas connections in the various countries . 108
A.7 Flue connections in the various countries . 110
)
Annex B (informative) Equivalence rules . 111
B.1 Conversion to categories within a restricted Wobbe index range . 111
B.2 Conversion to categories within an identical Wobbe index range. 111
B.3 Conversion to categories within a wider Wobbe index range . 112
Annex C (informative) A-deviations . 113
C.1 General . 113
C.2 Switzerland . 113
Annex D (normative) Special national conditions . 114
D.1 Special national conditions . 114
D.2 Belgium. 114
D.3 Italy . 114
D.4 Poland . 114
Annex E (informative) Identification of gas types in use in various countries . 115
Annex F (informative) National solutions for countries whose national bodies are Affiliate
Members of CEN . 116
F.1 Categories listed in the body of the standard and marketed in different countries . 116
F.2 Appliance supply pressures corresponding to the categories given in F.1 . 116
F.3 Special categories marketed nationally or locally . 116
F.4 Gases and test pressures corresponding to the special categories given in F.3 . 116
Annex G (informative) Calculation of conversions of NOx . 117
Annex H (informative) An example of sampling plans . 118
H.1 Sampling plans . 118
H.2 Inspection levels and procedures . 119
Annex ZA (informative) . 120
Annex ZB (normative) Clauses of this European Standard addressing the provisions of the EU
Construction Products Directive . 122
ZB.1 Scope and relevant characteristics . 122
ZB.2 Procedure(s) for attestation of conformity of [construction products] . 124
ZB.3 CE marking and labelling. 126
Bibliography . 128

Foreword
This document (EN 778:2009) has been prepared by Technical Committee CEN/TC 180 “Domestic and non-
domestic gas fired air heaters and non-domestic gas fired overhead radiant heaters”, the secretariat of which
is held by AFNOR.
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 April 2010, and conflicting national standards shall be withdrawn at the
latest by April 2010.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 778:1998.
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 ZA, and Annex ZB, which are integral parts of this
document.
This revision modifies EN 778:1998. It has been prepared to incorporate requirements for combustion
products evacuation ducts, POCEDs, supplied as an integral part of the system to support the EU Directive
89/106/EEC on construction products under mandate M 105. To this end, it extends the scope of the standard
to cover type B appliances.
Furthermore, the opportunity presented by this revision has been taken to update the standard in respect to
EN 437:2003.
NOTE For countries requesting special categories (specified in EN 437:2003), the absence of specific information
concerning A.3.3 and A.3.4 implies that the general requirements described in the body of the standard (see 4.1.1, 4.2.2,
4.2.3 and 4.2.5) also apply to these special categories.
 EN 525, Non-domestic direct gas-fired forced convection air heaters for space heating not exceeding a
net heat input of 300 kW
 EN 621, Non-domestic gas-fired forced convection air heaters for space heating not exceeding a net heat
input of 300 kW, without a fan to assist transportation of combustion air and/or combustion products
 EN 1020, Non-domestic gas-fired forced convection air heaters for space heating not exceeding a net
heat input of 300 kW, incorporating a fan to assist transportation of combustion air and/or combustion
products
 EN 1196, Domestic and non-domestic gas-fired air heaters ― Supplementary requirements for
condensing air heaters
 EN 1319, Domestic gas-fired forced convection air heaters for space heating, with fan-assisted burners
not exceeding a net heat input of 70 kW
 EN 12669, Direct gas-fired hot air blowers for use in greenhouses and supplementary non-domestic
space heating
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

1 Scope
This European Standard specifies the requirements and test methods for the safety and efficiency of domestic
gas-fired air heaters with (an) atmospheric burner(s) and without a fan to assist the transportation of
combustion air and/or flue gases, hereafter referred to as "appliances".
This European Standard applies to Type B , B , B , B , B , B C , C , C and C appliances
11 11AS 11BS 41 41AS 41BS 11 21 31 41
with an input not exceeding 70 kW (net cv-basis), intended primarily for use in single unit residential dwellings.
Provision of the heated air may be by means of ducting.
This European Standard does not apply to:
a) appliances of the condensing type;
b) appliances for outdoor installation;
c) dual purpose air conditioning appliances (heating and cooling);
d) appliances where the air is heated by an intermediate fluid;
e) appliances with forced draught burners;
f) appliances fitted with a manual or automatic means of adjusting the combustion air supply or the
combustion products evacuation (including flue dampers);
g) portable or transportable forced convection appliances;
h) appliances having multiple heating units with a single draught diverter;
i) appliances fitted with more than one flue outlet;
j) C and C appliances for 3rd family gases;
21 41
NOTE For C appliances, see all requirements and test methods that are valid for C appliances, unless otherwise
41 21
stated.
k) appliances that are designed for continuous condensation within the flue system under normal operating
conditions;
l) appliances having Products Of Combustion Evacuation Ducts (POCED), that are non-metallic.
This European Standard is applicable to appliances which are intended to be type tested. It also includes
requirements concerning the evaluation of conformity, including factory production control, but these
requirements only apply to POCEDs and their associated terminals.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 88-1:2007, Pressure regulators and associated safety devices for gas appliances — Part 1: Pressure
regulators for inlet pressures up to and including 500 mbar
EN 125:1991, Flame supervision devices for gas burning appliances — Thermo-electric flame supervision
devices
EN 126:2004, Multifuctional controls for gas burning appliances
EN 161:2007, Automatic shut-off valves for gas burners and gas appliances
EN 257:1992, Mechanical thermostats for gas-burning appliances
EN 298:2003, Automatic gas burner control systems for gas burners and gas burning appliances with or
without fans
EN 437:2003, Test gases — Test pressures — Appliance categories
EN 1859:2000, Chimneys — Metal Chimneys — Test methods
EN 10226-1:2004, Pipe threads where pressure tight joints are made on the threads — Part 1: Taper external
threads and parallel internal threads — Dimensions, tolerances and designation
EN 10226-2:2005, Pipe threads where pressure tight joints are made on the threads — Part 2: Taper external
threads and taper internal threads — Dimensions, tolerances and designation
EN 60335-1:2002, Household and similar electrical appliances — Safety — Part 1: General requirements (IEC
60335-1:2001, modified)
EN 60335-2-102:2006, Household and similar electrical appliances — Safety — Part 2-102: Particular
requirements for gas, oil and solid-fuel burning appliances having electrical connections
(IEC 60335-2- 102:2004, modified)
EN 60529:1992, Degrees of protection provided by enclosures (IP code) (IEC 60529:1989)
EN 60730-1:2000, Automatic electrical controls for household and similar use — Part 1: General requirements
(IEC 60730-1:1999, modified)
EN 60730-2-1:1997, Automatic electrical controls for household and similar use — Part 2-1: Particular
requirements for electrical controls for electrical household appliances (IEC 60730-2-1:1989, modified)
EN 60730-2-9:2002, Automatic electrical controls for household and similar use — Part 2-9: Particular
requirements for temperature sensing controls (IEC 60730-2-9:2000, modified)
EN 61058-1:2002, Switches for appliances — Part 1: General requirements (IEC 61058-1:2000 + A1:2001,
modified)
EN ISO 228-1:2003, Pipe threads where pressure-tight joints are not made on the threads — Part 1:
Dimensions, tolerances and designation (ISO 228-1:2000)
EN ISO 3166-1:2006, Codes for the representation of names of countries and their subdivisions Part 1:
Country codes (ISO 3166-1:2006)
EN ISO 6976:2005, Natural gas — Calculation of the calorific value, density, relative density and Wobbe index
from composition (ISO 6976:1995 including Corrigendum 1:1997, Corrigendum 2:1997 and Corrigendum
3:1999)
ISO 1182:2002, Reaction to fire tests for building products — Non-combustibility test
ISO 7005-1:1992, Metallic flanges — Part 1: Steel flanges
ISO 7005-2:1988, Metallic flanges — Part 2: Cast iron flanges
ISO 7005-3:1988, Metallic flanges — Part 3: Copper alloy and composite flanges
CR 1404, Determination of emissions from appliances burning gaseous fuels during type-testing
3 Terms and definitions
3.1 Appliance and its constituent parts
3.1.1
domestic air heater
appliance designed for the heating by means of warm air and possibly ventilation of a single unit residential
dwelling
3.1.2
forced convection air heater
appliance designed to provide space heating from a central source by distributing heated air, by means of an
air moving device, either through ducting or directly into the heated space
3.1.3
gas inlet connection
part of the appliance intended to be connected to the gas supply
3.1.4
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); flat joints
3.1.5
gas circuit
part of the appliance that conveys or contains the gas between the appliance gas inlet connection and the
burner(s)
3.1.6
restrictor
device with an orifice, which is placed in the gas circuit so as to create a pressure drop and thus reduce the
gas pressure at the burner to a predetermined value for a given supply pressure and rate
3.1.7
gas rate adjuster
component allowing an authorized person to set the gas rate of the burner to a predetermined value according
to the supply conditions
NOTE 1 Adjustment may 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.
3.1.8
setting an adjuster
immobilization of an adjuster (by some means such as e.g. a screw) after the manufacturer or installer has
adjusted it setting an adjuster
3.1.9
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;
the adjuster is then said to be "sealed" in its adjustment position
NOTE 1 A factory sealed adjuster is considered to be non-existent.
NOTE 2 A regulator is considered to be non-existent if it has been factory sealed in a position such that it is not
operational in the range of supply pressures corresponding to the appliance category.
3.1.10
putting an adjuster or a control out of service
putting an adjuster or a control (e.g. of temperature, pressure) out of action and sealing it in this position
the appliance then functions as if the adjuster or control had been removed
3.1.11
injector
component that admits the gas into a burner
3.1.12
main burner
burner that is intended to assure the thermal function of the appliance
3.1.13
ignition device
any 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.
3.1.14
ignition burner
burner whose flame is intended to ignite another burner
3.1.15
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".
3.1.16
combustion circuit
combustion circuit comprises the air supply circuit, the combustion chamber, the heat exchanger and the
combustion products evacuation circuit so far as this is part of the appliance
3.1.17
combustion chamber
enclosure inside which combustion of the air-gas mixture takes place
3.1.18
flue outlet
part of an appliance that connects with a flue to evacuate the products of combustion
3.1.19
draught diverter
device placed in the combustion products circuit to reduce the influence of flue-pull and that of down-draught
on the burner performance and combustion
3.1.20
flue terminal
device fitted at the end of the duct system which enables the discharge of flue gases and may, at the same
time, allow entry of combustion air
3.1.21
POCED
combustion products evacuation duct that is intended to be used only with a specific appliance/system; this
duct being either supplied with the appliance/system or specified in the manufacturers instructions
3.2 Adjustment, control and safety devices
3.2.1
range rating device
component on the appliance intended to be used by the installer to adjust the heat input of the appliance,
within a range of heat inputs stated by the manufacturer, to suit the actual heat requirements of the installation
NOTE This adjustment may be progressive (e.g. by use of a screw adjuster) or in discrete steps (e.g. by changing
restrictors).
3.2.2
automatic burner system
burner system in which, when starting from the completely shut-down condition, the start–gas flame is
detected and proved and the main gas valve(s) is(are) actuated without manual intervention
3.2.3
automatic burner control system
system comprising at least a programming unit and all the elements of a flame detector device;
the various functions of an automatic burner control system may be in one or more housings [EN 298:2003]
3.2.4
non-automatic burner control system
burner system with an ignition burner which is ignited manually
3.2.5
programming unit
device 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 lock-out;
the programming unit follows a predetermined sequence of actions and always operates in conjunction with a
flame detector device [EN 298:2003]
3.2.6
Programme
sequence of control operations determined by the programming unit involving switching on, starting up,
supervising and switching off the burner;
safety actions such as safety shut down and lock out are also part of the programme [EN 298:2003]
3.275
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, may be assembled in a single housing for use in conjunction with a
programming unit [EN 298:2003]
3.2.8
flame signal
signal given by the flame detector device, normally when the flame sensor senses a flame [EN 298:2003]
3.2.9
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]
3.2.10
1)
pressure regulator
device which maintains the outlet pressure constant independent of the variations in inlet pressure and/or flow
rate within defined limits
3.2.11
adjustable pressure regulator
regulator provided with means for changing the outlet pressure setting
3.2.12
flame supervision device
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
3.2.13
automatic shut-off valve
valve designed to open when energized and to close automatically when de-energized

1)
The term "regulator" is used in this case and for a volume regulator.

3.2.14
room temperature control thermostat
device controlling the operation of the appliance (by on/off, high/low or modulating control) and enabling the
room temperature to be kept automatically, within a given tolerance, at a predetermined value
3.2.15
overheat cut-off device
device that shuts off and locks out the gas supply before the appliance is damaged and/or before safety is put
into question, and that requires manual intervention to restore the gas supply
3.2.16
temperature limiter
device which is intended to keep a temperature below one particular value during normal operation conditions
and which may have a provision for setting by the user
3.2.17
overheat limit device
device which is intended to keep a temperature below one particular value during abnormal operation
conditions and which has either no provision for setting or is provided with a maximum temperature limit stop
NOTE The overheat limit device may be of the automatic or the manual reset type.
3.2.18
fan control
control that starts and/or stops the air delivery fan when the temperature of the delivered air reaches certain
predetermined values
3.2.19
temperature sensing element; temperature sensor
component that detects the temperature of the environment to be supervised or controlled
3.2.20
combustion product discharge safety system
system that automatically shuts off the gas supply to the main burner, and perhaps to the ignition burner,
when spillage of combustion products from the draught diverter is detected
3.2.21
atmosphere sensing device
device designed to shut off the gas supply before the concentration of combustion products of the surrounding
atmosphere reaches a set value
3.2.22
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
3.2.23
high/low control
automatic control which permits an appliance to operate either at the nominal heat input or at a fixed reduced
heat input
3.2.24
closed position indicator switch
switch fitted to an automatic shut-off valve which indicates when the closure member is in the closed position
3.2.25
proof of closure switch
switch fitted to an automatic shut-off valve with mechanical overtravel which indicates when the closure
member is in the closed position
3.2.26
valve proving system
system to check the effective closure of automatic shut-off valves
3.3 Operation of the appliance
3.3.1
volume flow rate
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 h (m /h), litres per min (l/min), cubic decimetres per h
3 3
(dm /h) or cubic decimetres per second (dm /s). [EN 437:2003]
3.3.2
mass flow rate
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]
3.3.3
heat input
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]
3.3.4
nominal heat input
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
3.3.8
light-back at the injector
ignition of the gas at the injector, either as a result of light-back into the burner or by the propagation of a
flame outside the burner
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
3.3.11
first safety time
interval between the ignition burner gas valve, the start gas valve or main gas valve, as applicable, being
energized and the ignition burner gas valve, start gas valve or main gas valve, as applicable, being de-
energized if the flame detector signals the absence of a flame at the end of this interval
NOTE Where there is no second safety time, this is called the safety time.
3.3.12
second safety time
where there is a first safety time to either a ignition burner or start gas flame only, the interval between the
main gas valve being energized and the main gas valve being de-energized if the flame detector signals the
absence of a flame
3.3.13
waiting time
time between safety shut-down any (re)start attempt
3.3.14
start gas
gas that is supplied at the start gas rate to establish the start gas flame
3.3.15
start gas rate
restricted gas flow rate admitted either to a separate ignition burner or to the main burner during the first
safety time
3.3.16
start gas flame
flame established at the start gas rate either at the main burner or at a separate ignition burner
3.3.17
running condition of the system
running condition 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;
the resulting state of the system is defined by deactivated terminals for the gas shut-off valves and the ignition
device [EN 298:2003]
3.3.20  Lock-out
3.3.20.1
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 [EN 298:2003]
3.3.20.2
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 electrical supply and its subsequent restoration [EN 298:2003]
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 ends with the restoration of the running condition or, if there is no flame signal at the end of the
safety time, with non-volatile lock-out
3.3.22
automatic recycling
process by which, following loss of flame signal during the running condition or accidental interruption of the
operation of the appliance, the gas supply is interrupted and the complete start sequence is automatically re-
initiated. This process ends with the restoration of the running condition or, if there is no flame signal at the
end of the safety time, or, if the cause of the accidental interruption has not disappeared, with volatile lock-out
or non-volatile lock-out
3.3.23
ignition opening time
time interval between ignition of the supervised flame and the moment when the valve is held open
3.3.24
extinction safety time
time interval between extinction of the supervised flame and the gas supply being shut off to the main burner
and/or to the ignition burner
3.4 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 millibars (mbar) or bars.
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 millibars (mbar) - 1 mbar = 10 Pa [EN 437:2003]
3.4.6
normal pressure
p
n
pressure under which the appliance operates in nominal conditions when supplied with the corresponding
reference gas [EN 437:2003]
3.4.7
limit pressure
(maximum limit pressure p and minimum limit pressure p )
max min
pressures representative of the extreme variations in the appliance supply conditions [EN 437:2003]
3.4.8
pressure couple
combination of two distinct gas distribution pressures applied by reason of the significant difference existing
between the Wobbe indices within a single family or group in which:
 the higher pressure corresponds only to gases of low Wobbe index;
 the lower pressure corresponds to gases of high Wobbe index [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
3.4.10
calorific value
quantity of heat produced by the complete combustion, at a constant pressure equal to 1 013,25 mbar, of a
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 H in which the water produced by combustion is assumed to be condensed;
s
 the net calorific value H in which the water produced by combustion is assumed to be in the vapour
i
state
NOTE The calorific value is expressed either in megajoules per cubic metre of dry gas at the reference conditions
(MJ/m )or in megajoules per kilogram of dry gas (MJ/kg) [EN 437:2003]
3.4.11
Wobbe index
gross Wobbe index: W ; net Wobbe index: W
s i
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
NOTE The Wobbe index is expressed either in megajoules per cubic metre of dry gas at the reference conditions
(MJ/m ) or in megajoules per kilogram of dry gas (MJ/kg) [EN437:2003]
3.5 Conditions of operation and measurement
3.5.1
reference conditions:
 for calorific values, temperature: 15 °C;
 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
3.5.3
hot condition
condition of the appliance required for some tests and obtained by heating to thermal equilibrium at the
nominal heat input specified by the manufacturer, any thermostat remaining fully open
3.5.4
thermal equilibrium
operating state of the appliance corresponding to a particular setting of the input, in which the measured value
of the flue gas temperature remains steady within a tolerance of ± 2 % (°C reading) over a period of 10 min
3.6 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 putting the appliance on the market and/or of installation, the appliance shall be capable of
operating, without adjustment or modification, with one of the gases distributed in the country concerned, at
the appropriate supply pressure
NOTE 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;
subsequent modification or adjustment is essential in order that it can be utilized safely and correctly in this
country
4 Classification
4.1 Classification of gases
Gases are classified into three families, possibly div
...