EN 13384-2:2015

SLOVENSKI STANDARD
01-junij-2015
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SIST EN 13384-2:2003+A1:2009
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Chimneys - Thermal and fluid dynamic calculation methods - Part 2: Chimneys serving
more than one heating appliance
Abgasanlagen - Wärme- und strömungstechnische Berechnungsverfahren - Teil 2:
Abgasanlagen mit mehreren Feuerstätten
Conduit de cheminée - Méthode de calcul thermo-aéraulique - Partie 2: Conduits de
fumée desservant plus d'un appareil de chauffage
Ta slovenski standard je istoveten z: EN 13384-2:2015
ICS:
91.060.40 Dimniki, jaški, kanali Chimneys, shafts, ducts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 13384-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2015
ICS 91.060.40 Supersedes EN 13384-2:2003+A1:2009
English Version
Chimneys - Thermal and fluid dynamic calculation methods -
Part 2: Chimneys serving more than one heating appliance
Conduits de fumée - Méthodes de calcul thermo-aéraulique Abgasanlagen - Wärme- und strömungstechnische
- Partie 2: Conduits de fumée desservant plus d'un appareil Berechnungsverfahren - Teil 2: Abgasanlagen mit mehreren
de chauffage Feuerstätten
This European Standard was approved by CEN on 24 January 2015.

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-CENELEC 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-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13384-2:2015 E
worldwide for CEN national Members.

Contents Page
Foreword .5
Introduction .6
1 Scope .7
2 Normative references .7
3 Terms and definitions .8
4 General symbols and abbreviations .9
5 Calculation method.9
5.1 General principles.9
5.2 Pressure equilibrium condition . 11
5.2.1 Negative pressure chimneys . 11
5.2.2 Positive pressure chimneys . 12
5.3 Mass flow requirement . 13
5.4 Pressure requirements . 13
5.4.1 Negative pressure chimneys . 13
5.4.2 Positive pressure chimneys . 14
5.5 Temperature requirement . 15
5.6 Calculation procedure . 15
6 Flue gas data characterising the heating appliance . 18
7 Data for chimney and connecting flue pipes . 19
8 Basic data for the calculation . 20
8.1 General . 20
8.2 Air temperatures . 20
8.2.1 External air temperature (T ) . 20
L
8.2.2 Ambient air temperature (T ) . 20
u
8.3 External air pressure (p ) . 20
L
8.4 Gas constant . 20
8.4.1 Gas constant of the air (R ) . 20
L
8.4.2 Gas constant of flue gas (R) . 20
8.5 Density of air (ρ ) . 20
L
8.6 Specific heat capacity of the flue gas (c ) . 20
p
8.7 Water vapour content (σ(H O) ) and condensing temperature (T ) . 20
2 ,j sp
8.8 Correction factor for temperature instability (S ) . 21
H
8.9 Flow safety coefficient (S ) . 21
E
8.10 External coefficient of heat transfer . 21
9 Determination of temperatures . 21
10 Mixing calculations . 23
10.1 General . 23

10.2 Flue gas mass flow ( m ) . 23
,j
10.3 Flue gas temperature at the inlet of the chimney segment (T ) . 23
e,j
10.4 CO -content of the flue gas in the chimney segment (σ(CO ) ) . 23
2 2 ,j
10.5 H O-content of the flue gas (σ(H O) ) . 24
2 2 ,j
10.6 Gas constant of the flue gas (R ) . 24
,j
10.7 Flue gas data . 24
10.7.1 Specific heat capacity (c ), (c ) . 24
pV,j p,j
10.7.2 Thermal conductivity of the flue gas (λ ), (λ ) . 24
AV,j A,j
10.7.3 Dynamic viscosity (η ), (η ) . 25
AV,j A,j
10.7.4 Condensing temperature (T ) . 25
SP
11 Density and velocity of the flue gas . 25
12 Determination of the pressures . 26
12.1 Pressures at each inlet of the chimney segments . 26
12.1.1 Draught . 26
12.1.2 Positive pressure . 26
12.1.3 Draught due to chimney effect in the chimney segment (P ) . 27
H,j
12.1.4 Pressure resistance in the chimney segment (P ) . 27
R,j
12.2 Minimum draught required at the flue gas inlet into the chimney and maximum allowed
and P ) and maximum and minimum differential pressure at the flue gas
draught (P
Ze Zemax
and P ) . 29
inlet into the chimney (P
ZOe ZOemin
12.2.1 Minimum required and maximum allowed draught . 29
12.2.2 Maximum available and minimum allowed differential pressure . 29
12.2.3 Calculated pressure resistance of the connecting flue pipe (P ) . 30
V,j
12.2.4 Calculated pressure resistance of the air supply (P ) . 32
Bc,j
13 Inner wall temperature . 33
14 Cascade installations . 33
14.1 Principle of the calculation method . 33
14.2 Pressure equilibrium condition . 34
14.2.1 Negative pressure cascade installation . 34
14.2.2 Positive pressure cascade installation . 35
14.3 Mass flow requirement . 36
14.4 Pressure requirements . 36
14.4.1 Negative pressure chimneys . 36
14.4.2 Positive pressure chimneys . 37
14.5 Temperature requirement . 38
14.6 Calculation procedure . 38
14.7 Pressures at the outlet of the connecting flue pipe and pressures at the inlet of the

collector segment . 38
14.7.1 Pressure at the flue gas inlet into the collector segment (P or P ). 38
ZC,j,l ZOC,j,l
14.7.2 Pressures required or available at the outlet of the connecting flue pipe (P , P ) . 42
ZeC,j,l ZOeC,j,l
14.8 Inner wall temperature (T ) . 44
iobC,j,l
15 Balanced flue chimney . 44
15.1 Principle of the calculation method . 44
15.2 Pressure equilibrium condition . 44
15.3 Mass flow requirement . 45
15.4 Pressure requirements . 45
15.4.1 Negative pressure chimneys . 45
15.4.2 Positive pressure chimneys . 45
15.5 Temperature requirements . 47
15.6 Calculation procedure for balanced flue chimneys . 47
15.7 Mass flow of the supply air . 49
15.8 Determination of the temperatures in balanced flue chimneys. 50
15.8.1 Separate ducts . 50
15.8.2 Concentric ducts . 50
15.8.3 Concentric connection pipes . 58
15.9 Pressures of the air supply ducts . 64
15.9.1 Draught due to chimney effect of the air supply duct of chimney segment j . 64
15.9.2 Draught due to chimney effect of the air supply duct of connection pipes . 64
15.9.3 Pressure resistance of the air supply duct of the chimney segment j (P ) . 64
RB,j
15.9.4 Pressure resistance of the air supply duct of the connection pipe j (P ) . 66
RBV,j
15.10 Density and velocity of the supply air . 68
15.10.1 Density and velocity of the supply air in the air supply duct averaged over the length of

the chimney segment . 68
15.10.2 Density and velocity of the supply air averaged over the length of the connection pipes . 68
16 Consideration of chimney fans . 69
16.1 General . 69
16.2 Inline fans . 70
16.3 Exhaust fans . 71
Annex A (informative) Recommendations . 72
A.1 General . 72
A.2 Recommendations for the chimney and heating appliances . 72
A.3 Recommendations for connecting flue pipes . 72
Annex B (informative) Characteristics for the heating appliance . 73

Foreword
This document (EN 13384-2:2015) has been prepared by Technical Committee CEN/TC 166 “Chimneys”, the
secretariat of which is held by ASI.
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 October 2015, and conflicting national standards shall be withdrawn at
the latest by October 2015.
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 13384-2:2003+A1:2009.
According to EN 13384-2:2003+A1:2009 the following fundamental changes are given:
— editorial mistakes have been corrected;
— mistakes in formulas have been corrected;
— characteristic values for heating appliances for solid fuel and for liquid fuels in Annex B have been
adapted to actual data;
— for the mixture of fuels a clarification about the rise of the dew point has been added;
— for non-concentric ducts the calculation of the mean temperature of the air supply has been amended;
— the process for iteration for appliances with low impact of the pressure to the flue gas mass flow (e.g.
CHP with combustion engine) has been simplified;
— for chimney fans a calculation procedure has been added;
This standard is one of a series of standards prepared by CEN/TC 166 comprising product standards and
execution standards for chimneys.
National installation rules are not regarded in the standard.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
This European Standard “Chimneys — Thermal and fluid dynamic calculation methods” consists of three
Parts:
— Part 1: Chimneys serving one heating appliance
— Part 2: Chimneys serving more than one heating appliance
— Part 3: Methods for the development of diagrams and tables for chimneys serving one heating appliance
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Introduction
The calculation described in this standard is complex and is intended to be solved by using a computer
programme. The general principles of this calculation method of EN 13384-1 also apply to this standard.
This standard is in support of the execution standards for a chimney installation serving more than one
heating appliance.
The execution standard identifies limitations and safety considerations associated with the design, installation,
commissioning and maintenance of a chimney serving more than one heating appliance (not dealt within the
calculation method).
1 Scope
This part of EN 13384 specifies methods for calculation of the thermal and fluid dynamic characteristics of
chimneys serving more than one heating appliance.
This part of EN 13384 covers both the cases, either
a) where the chimney is connected with more than one connecting flue pipe from individual or several
appliances in a multi-inlet arrangement; or
b) where the chimney is connected with an individual connecting flue pipe connecting more than one
appliance in a cascade arrangement.
The case of multiple inlet cascade arrangement is covered by the case a).
This part of EN 13384 deals with chimneys operating under negative pressure conditions (there can be
positive pressure condition in the connecting flue pipe) and with chimneys operating under positive pressure
conditions and is valid for chimneys serving heating appliances for liquid, gaseous and solid fuels.
This part of EN 13384 does not apply to:
— chimneys with different thermal resistance or different cross-section in the various chimney segments.
This part does not apply to calculate energy gain;
— chimneys with open fire places, e.g. open fire chimneys or chimney inlets which are normally intended to
operate open to the room;
— chimneys which serve different kinds of heating appliances regarding natural draught, fan assisted, forced
draught or combustion engine. Fan assisted appliances with draught diverter between the fan and the
chimney are considered as natural draught appliances;
— chimneys with multiple inlets from more than 5 storeys. (This does not apply to balanced flue chimney.);
— chimneys serving heating appliances with open air supply through ventilation openings or air ducts, which
are not installed in the same air supply pressure region (e.g. same side of building).
For positive pressure chimneys this part only applies if any heating appliance which is out of action can be
positively isolated to prevent flue gas back flow.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 1443:2003, Chimneys - General requirements
EN 13384-1:2015, Chimneys - Thermal and fluid dynamic calculation methods - Part 1: Chimneys serving one
appliance
EN 15287-1:2007+A1:2010, Chimneys - Design, installation and commissioning of chimneys - Part 1:
Chimneys for non-roomsealed heating appliances
EN 15287-2:2008, Chimneys - Design, installation and commissioning of chimneys - Part 2: Chimneys for
roomsealed appliances
prEN 16475-2, Chimneys - Accessories - Part 2: Chimney fans - Requirements and test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1443:2003, EN 13384-1:2015,
EN 15287-1:2007+A1:2010, EN 15287-2:2008 and the following apply.
3.1
chimney segment
part of a chimney between two consecutive flue gas connections or between the last flue gas connection and
the chimney outlet
3.2
collector segment
part of a connecting flue pipe between two consecutive flue gas connections or between the last flue gas
connection and the chimney inlet
3.3
flue gas mass flow

m
mass of the flue gas leaving the heating appliance through the connecting flue pipe per unit of time
Note 1 to entry: In case of a chimney serving more than one heating appliance, the air being transported through an
appliance which is out of action is also given the term flue gas mass flow.
3.3.1
declared flue gas mass flow
m
W,j
flue gas mass flow given by the manufacturer of the heating appliance j with respect to the heat output used in
the calculation
3.3.2
calculated flue gas mass flow
m
Wc,j
flue gas mass flow calculated with respect to calculated draught and the working conditions of the heating
appliance j
3.4
calculated flue gas temperature
T
Wc,j
flue gas temperature at the outlet of the heating appliance j depending on the calculated flue gas mass flow
3.5
calculated draught of the flue gas of the heating appliance
P
Wc,j
draught at the flue gas outlet of the heating appliance j depending on the calculated flue gas mass flow
3.6
flue damper
device to close or partially close the flue
3.7
balanced flue chimney
chimney where the point of air entry to the combustion air duct is adjacent to the point of discharge of
combustion products from the flue, the inlet and outlet being so positioned that wind effects are substantially
balanced
3.8
cascade arrangement
arrangement where two or more appliances situated in the same space are connected by a common
connecting flue pipe to the chimney
3.9
multi inlet arrangement
arrangement where two or more appliances are connected to the chimney by individual connecting flue pipes
3.10
air duct
independent duct in a building or a structural part of a flue terminal conveying combustion air to a room-sealed
appliance
3.11
pressure equalizing opening
opening or duct that directly connects the air duct with the flue at its base
4 General symbols and abbreviations
Symbols, terminology and units are given to make the text of this standard understandable. A list of general
symbols and abbreviations is given in EN 13384-1 Indices added to symbols for purposes of the calculation
method for chimneys serving more than one heating appliance relate to one chimney segment and/or
connection flue pipe section. An example of an indices numbering scheme is given in Figures 1 and 2. Indices
numbering shall begin at the lowest, farthest appliance connection. For more than one cascade
system/connection, the indices numbering scheme for the calculation formula should be adopted in a similar
manner to that for a single cascade scheme. Symbols assigned to a specific section will be indicated by the
number of the section after the comma (e. g. H is the effective height of a section of a chimney segment
,1
between the outlet of the connecting flue pipe of the heating appliance in the lowest position and the outlet of
the connecting flue pipe of the next heating appliance).
Each symbol and abbreviation is explained at the formula where it is used.
5 Calculation method
5.1 General principles
The calculation is based upon determining the mass flow distribution in the chimney which fulfils the pressure
equilibrium condition (Formula (1)) at each flue gas inlet to the chimney (see Figure 1). After such a
distribution has been found four requirements shall be verified:
a) the mass flow requirement (Formulas (4) and (5))
b) the pressure requirement for minimum draught or maximum positive pressure (Formulas (6) or (6b) and
(6c))
c) the pressure requirement for maximum draught or minimum positive pressure (Formulas (6a) or (6d))
d) the temperature requirement (Formula (7))
NOTE 1 The calculation is affected by the specific installation design. For recommendations for the installation of
appliance and connection flue pipes see Annex A.
NOTE 2 The pressure requirements for maximum draught or minimum positive pressure are only required if there is a
limit for the maximum draught for the (negative pressure) heating appliance or a minimum differential pressure of the
(positive pressure) heating appliance.
In order to verify the criteria two sets of external conditions are used:
— the calculation of the minimum draught and maximum positive pressure (draught) is made with conditions
for which the capacity of the chimney is minimal (i.e. high outside temperature); and also
— the calculation of the maximum draught and minimum positive pressure and of the inner wall temperature
with conditions for which the inside temperature of the chimney is minimal (i.e. low outside temperature).
The validation of the mass flow requirement and pressure requirement shall be done at following working
conditions, using the external and ambient air temperatures specified in EN 13384-1.
— All heating appliances are simultaneously operating at nominal heat output.
— All heating appliances are simultaneously operating at minimum heat output
— A single heating appliance operating at nominal heat output and all other appliances out of action (all
possible cases)
— A single heating appliance operating at minimum heat output and all other appliances out of action (all
possible cases)
For positive pressure chimneys a single heating appliance operating at minimum nominal heat output and all
other appliances operating at maximum nominal heat output (all possible cases) If the control of the
installation guarantees that not all appliances will be in operation simultaneously, the validation of the mass
flow requirement and pressure requirement may be done with the maximum number of appliances which will
be in operation under the most adverse condition.
The validation for the mass flow requirement and pressure requirement for working conditions with heating
appliances at minimum heat output is not required in the following cases:
— the heating appliances do not have any heat output range
— the heating appliances have a heat output which is limited to a fixed value as specified on a label on the
appliance. In this case the nominal heat output is the given heat output on the label.
— heating appliances heated with solid fuels without fan and appliances with regulated air supply.
The validation of the mass flow requirement for working conditions with appliances at nominal heat output is
not required in the following case:
— the heating appliances have a flue gas mass flow at minimum heat output higher than or equal to the flue
gas mass flow at nominal heat output.
The temperature requirement shall be validated for the following relevant working condition, using the ambient
and external air temperatures as specified in EN 13384-1:
— heating appliances for solid fuels without fan and heating appliances with regulated air supply are in
operation at nominal heat output,
— heating appliances with a draught diverter which provide domestic hot water only are out of action. These
heating appliances operate with a considerable secondary air (These operate only a short time and
therefore it can be assumed that condensation will not cause damage or a lack in safety);
— heating appliances with a fixed output range are in operation at this (nominal) heat output;
— all other heating appliances are in operation at minimum heat output.
When chimneys suitable for operating under wet conditions are located inside a building the check of the
temperature requirement is necessary only for the top of the chimney.
The validation of the temperature requirement is not necessary when the chimney serves only domestic gas
fired water heaters with instantaneous production and domestic gas fired storage water heaters.
If the chimney system includes a draught regulator, the system is handled as a cascade system.
5.2 Pressure equilibrium condition
5.2.1 Negative pressure chimneys
The following formulas shall be fulfilled for each chimney segment j at all relevant working conditions:
P −≤P 0,1, in Pa (1)
Z, jjZe,
N
P =−P+ (P − P ) , in Pa (2)
Z, j L H,k R,k
∑
k= j
P = P + P + P , in Pa (3)
Ze,j Wc,j V,j Bc,j
where
P draught at the flue gas inlet to the chimney segment j, in Pa
Z,j
P theoretical draught due to chimney effect in chimney segment k, in Pa
H,k
P pressure resistance of the chimney segment k, in Pa
R,k
P calculated draught of the heating appliance, in Pa
Wc,j
P calculated pressure resistance of the connecting flue pipe of chimney segment j, in Pa
V,j
P calculated pressure resistance of the air supply for the heating appliance j, in Pa
Bc,j
P required draught at the flue gas inlet to the chimney segment j, in Pa
Ze,j
P wind velocity pressure, in Pa
L
N number of heating appliances
Key
1 chimney
2 connecting flue pipe j
3 heating appliance j
4 connecting flue pipe 2
5 heating appliance 2
6 connecting flue pipe 1
7 heating appliance 1
8 chimney segment 1
9 chimney segment j
Figure 1 — Example of multiple inlet arrangement and numbering pressure values and temperature
values of a chimney serving more than one heating appliance
5.2.2 Positive pressure chimneys
The following formulas shall be fulfilled for each chimney segment j at all relevant working conditions:
P − P ≤ 0,1, in Pa (3a)
ZOe, j ZO, j
N
P =P+−(PP ) , in Pa (3b)
ZO,j L ∑ R,k H,k
k= j
P P− PP− , in Pa (3c)
ZOe, j WOc,j V,j Bc,j
where
P positive pressure at the flue gas inlet to the chimney segment j, in Pa
ZO,j
=
PH,k theoretical draught due to chimney effect in chimney segment k, in Pa
P pressure resistance of the chimney segment k, in Pa
R,k
P
WOc,j calculated positive differential pressure of the heating appliance j, in Pa
PV,j calculated pressure resistance of the connecting flue pipe of chimney segment j, in Pa
P calculated pressure resistance of the air supply for the heating appliance j, in Pa
Bc,j
P
ZOe,j maximum differential pressure at the flue gas inlet to the chimney segment j, in Pa
PL wind velocity pressure,
N number of heating appliances
5.3 Mass flow requirement
Formulas (4) and/or (5) shall be verified for all relevant working conditions (see 5.6).
For each heating appliance in operation at nominal or minimum heat output:
m ≥ m , in kg/s (4)
Wc,j W,j
and for each heating appliance out of action:
m ≥ 0 , in kg/s (5)
Wc,j
where
calculated mass flow of the heating appliance, in kg/s
m
Wc,j
declared mass flow of the heating appliance, in kg/s
m
W,j
Where a damper is applied, flow resistance shall be taken as 0 unless additional data are available.
5.4 Pressure requirements
5.4.1 Negative pressure chimneys
For negative pressure chimneys it has to be additionally checked that the negative pressure (minimum
draught) in the chimney (P ) is more than or equal to the negative pressure in the room where the heating
Z,j
appliance is placed at calculated draught conditions for air supply. The check on this pressure requirement
shall be done using the same conditions as specified for the check on the mass flow requirement (see 5.3 and
5.6). The following relations shall be verified:
P ≥ P , in Pa (6)
Z,j Bc,j
where
P draught at the inlet to the chimney segment j, in Pa
Z,j
P calculated pressure resistance of the air supply for the heating appliance j, in Pa
Bc,j
If required it has to be additionally checked that the negative pressure (draught) in the chimney (P ) is less
Zmax,j
than or equal to the maximum allowed draught (P ) caused by the heating appliance. The Formula (6a)
Zemax,j
shall be verified for all relevant working conditions (see 5.6).
The check of this pressure requirement shall be done with a separate calculation using the newly calculated
flue mass flows that fulfil the pressure equilibrium conditions at an external air temperature of T = 258,15 K (t
L L
= -15 °C, see EN 13384-1).
N
P = (P − P ) ≤ P + P + P = P , in Pa (6a)
Zmax, j H,k R,k Wmax,j V,j Bc,j Zemax,j
∑
k= j
where
P maximum draught at the flue gas inlet into the chimney segment j, in Pa
Zmax,j
P
maximum allowed draught at the flue gas inlet into the chimney segment j, in Pa
Zemax,j
P theoretical draught due to chimney effect in chimney segment k, in Pa
H,k
P
pressure resistance of the chimney segment k, in Pa
R,k
P maximum draught for the heating appliance j, in Pa
Wmax,j
P calculated pressure resistance of the connecting flue pipe of chimney segment j, in Pa
V,j
P calculated pressure resistance of the air supply for the heating appliance j, in Pa
Bc,j
NOTE The values of P , P , P and P in Formulas (2) and (6a) are normally different because the conditions
H,k R,k V,j Bc,j
are different.
5.4.2 Positive pressure chimneys
For positive pressure chimneys it has to be additionally checked that the maximum positive pressure in the
connecting flue pipe (P + P ) and in the chimney (P ) is not higher than the excess pressure for which
ZO,j V,j ZO,j
both are designated (P and P ). The check on the pressure requirement shall be done using the
ZV excess Z excess
same conditions as specified for the check on the mass flow requirement (see 5.3 and 5.6). The following
relations shall be verified:
P ≤ P , in Pa (6b)
ZO,j Z excess
P + P ≤ P , in Pa (6c)
ZO,j V,j ZV excess
where
P positive pressure at the flue gas inlet to the chimney segment j, in Pa
ZO,j
P calculated pressure resistance of the connecting flue pipe of chimney segment j, in Pa
V,j
P is the maximum allowed pressure from the designation of the chimney, in Pa
Z excess
P is the maximum allowed pressure from the designation of the connecting flue pipe, in Pa
ZV excess
If required it has to be additionally checked that the minimum positive pressure in the chimney (P ) is
ZOmin,j
more than or equal to the minimum allowed positive pressure (P ) caused by the heating appliance. The
ZOemin,j
relation (6d) shall be verified for all relevant working conditions (see 5.6).
The check of this pressure requirement shall be done with a separate calculation using the newly calculated
flue mass flows that fulfil the pressure equilibrium conditions at an external air temperature of
T = 258,15 K (t = -15 °C, see EN 13384-1).
L L
N
P = (P − P ) ≥ P − P − P = P , in Pa (6d)
ZOmin,j ∑ R,k H,k WO min,j Bc,j V,j ZOe min,j
k= j
where
P minimum positive pressure at the flue gas inlet into the chimney segment j, in Pa
ZOmin,j
P minimum differential pressure at the flue gas inlet into the chimney segment j, in Pa
ZOemin,j
P
theoretical draught due to chimney effect in chimney segment k, in Pa
H,k
P pressure resistance of the chimney segment k, in Pa
R,k
P
minimum differential pressure of the heating appliance j, in Pa
WOmin,j
P calculated pressure resistance of the air supply for the heating appliance j, in Pa
Bc,j
P calculated pressure resistance of the connecting flue pipe of chimney segment j, in Pa
V,j
NOTE The values of P and P in Formulas (3b) and (6d) are normally different because the conditions are
H,k R,k
different.
5.5 Temperature requirement
The relation (7) shall be verified for all relevant working conditions (see 5.6).
The check of the temperature requirement shall be done with a separate calculation using the newly
calculated flue mass flows that fulfil the pressure equilibrium conditions at an external air temperature of T
o,j
u
(see EN 13384-1)
T ≥ T , in K (7)
iob,j g,j
where
T temperature of the inner wall of the chimney segment j at the end, in K
iob,j
T temperature limit for chimney segment j, in K
g,j
The temperature limit T for chimneys suitable for operating under dry conditions is equal to the condensing
g,j
temperature T of the flue gas (see 8.6). T = T
sp,j g,j sp,j
The temperature limit T for chimneys suitable for operating under wet conditions is equal to the freezing
g,j
point of water: T = 273,15 K.
g,j
NOTE The following cases can be exempted from meeting the temperature requirement provided that it is accepted
that in case the requirement for temperature should be not fulfilled no guarantee can be given that no moisture appears. In
this cases insulation is advised.
— heating appliances which are substituted to a usual chimney which is already in operation and
— the heat output of the heating appliances which are connected and/or substituted does not exceed 30 kW
for each and
— the flue gas losses are not more or equal than 8 % and
— an effective air conditioning of the chimney during standstill periods is given by draught diverters or
dampers and
— sufficient standstill periods are given (e. g. the minimum steady state heat output of the heating appliance
is not less than 20 % as the required heat).
5.6 Calculation procedure
For the calculation of the pressure and temperature values in a chimney serving more than one heating
appliance an iterative procedure is necessary. This calculation procedure is based on the application of mass
and energy conservation formulas under quasi steady state conditions.
In each point of connection between various ducts (at the end of connecting flue pipes, the beginning and the
end of the chimney segments), all called nodes (see Figure 2), the following procedure shall be used:

Figure 2 — Designation of flow numbering for each node j (see Formulas (8) and (9))
— The mass flow and the temperature shall be calculated with Formulas (8) and (9).
m + m = m , in kg/s (8)
,j-1 V,j ,j
m⋅c ⋅T + mm⋅c ⋅T = ⋅⋅cT , in J/s (9)
,j-1 p,j-1 o,j-1 V,j pV,j oV,j ,j p,j e,j
where
flue gas mass flow in chimney segment j-1, in kg/s
m
,j-1
flue gas mass flow in connecting flue pipe, in kg/s
m
V,j
flue gas mass flow in chimney segment j, in kg/s
m
,j
c specific heat capacity of flue gas in chimney segment j-1, in J/( kg ⋅ K)
p,j-1
c specific heat capacity of flue gas in connecting flue pipe j, in J/( kg ⋅ K)
pV,j
c specific heat capacity of flue gas in chimney segment j, in J/( kg ⋅ K)
p,j
T temperature of the flue gas at the end of chimney segment j-1, in K
o,j-1
T temperature of the flue gas at the end of connecting flue pipe j, in K
oV,j
T temperature of the flue gas at the inlet of chimney segment j, in K
e,j
— The draught or positive pressure at the beginning of the chimney segment (at point 3), i
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