SIST EN 15316-3-3:2007
Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies - Part 3-3: Domestic hot water systems, generation
Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies - Part 3-3: Domestic hot water systems, generation
This standard is part of the method for calculation of system energy requirements and system efficiencies.
The scope of this specific part is to standardise the methods for calculation of the heat losses from the domestic hot water generation system and it defines the:
- inputs;
- outputs;
- calculation method.
This standard covers the domestic hot water requirements in all buildings.
The general approach to calculate energy consumptions and losses of domestic hot water systems is as follows:
- calculation of domestic hot water requirements of a dwelling, a zone or a building ( );
- calculation of heat losses due to the distribution or circulation of domestic hot water supplied ( );
- calculation of heat losses in hot water storage units ( ) and heat losses due to the production or generation ( ).
In order to be coherent with calculation methods for space heating systems, emission losses representing taps and control should be taken into account.
Heizsysteme in Gebäuden - Verfahren zur Berechnung der Energieanforderungen und Nutzungsgrade der Anlagen - Teil 3-3: Trinkwassererwärmung, Erzeugung
Diese Norm ist Teil des Verfahrens zur Berechnung der Energieanforderungen und Nutzungsgrade der Anlagen.
Der Anwendungsbereich dieses speziellen Teils umfasst die Normung der Verfahren zur Berechnung der Wärmeverluste der Trinkwarmwasseranlage und definiert Folgendes:
- Inputgrößen;
- Outputgrößen;
- Berechnungsverfahren.
Diese Norm legt die Anforderungen an die Trinkwassererwärmung in allen Gebäuden fest.
Der allgemeine Ansatz bei der Berechnung des Energieverbrauchs und der Verluste von Trinkwarmwasseranlagen ist wie folgt:
- Berechnung des Nutzwärmebedarfs Trinkwarmwasser für ein Wohnhaus, eine Zone oder ein Gebäude (QW);
- Berechnung der Wärmeverluste durch die Verteilung oder Zirkulation des bereitgestellten Trinkwarmwassers (QW, d);
- Berechnung der Wärmeverluste in Warmwasser Speichern (QW, s) und der Wärmeverluste der Erzeugung (QW, g).
Um eine Übereinstimmung mit den Berechnungsverfahren für die Heizungsanlagen zu erreichen, sollten auch Übergabeverluste durch Wasserhähne und Regelvorrichtungen berücksichtigt werden.
Systemes de chauffage dans les bâtiments - Méthode de calcul des exigences énergétiques et des rendements du systeme - Partie 3.3 : Systemes d'eau chaude domestique, production
La présente Norme européenne fait partie d’une série de normes traitant des méthodes de calcul des besoins énergétiques et des rendements des systèmes de chauffage dans les bâtiments. Elle traite, en particulier, des systèmes de production d’eau chaude sanitaire.
L’objet de cette partie spécifique est de normaliser les méthodes de calcul :
des pertes thermiques du système de génération d’eau chaude sanitaire ;
des pertes thermiques du système de génération d’eau chaude sanitaire récupérables pour le chauffage des locaux ;
de l’énergie des auxiliaires des systèmes de génération d’eau chaude sanitaire.
Ces valeurs sont les données d’entrée pour le calcul de l’utilisation totale d’énergie conformément au prEN 15603 et à l’EN 15316-1.
Cette Norme européenne spécifie :
les données d’entrée ;
les méthodes de calcul ;
les données de sortie.
Grelni sistemi v stavbah - Metoda izračuna energijskih zahtev in učinkovitosti sistema - 3-3. del: Hišna proizvodnja tople vode
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies - Part 3-3: Domestic hot water systems, generationXþLQNRYLWRVWLSystemes de chauffage dans les bâtiments - Méthode de calcul des exigences énergétiques et des rendements du systeme - Partie 3.3 : Systemes d'eau chaude domestique, productionHeizsysteme in Gebäuden - Verfahren zur Berechnung der Energieanforderungen und Nutzungsgrade der Anlagen - Teil 3-3: Trinkwassererwärmung, ErzeugungTa slovenski standard je istoveten z:EN 15316-3-3:2007SIST EN 15316-3-3:2007en,de91.140.10Sistemi centralnega ogrevanjaCentral heating systemsICS:SLOVENSKI
STANDARDSIST EN 15316-3-3:200701-december-2007
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15316-3-3October 2007ICS 91.140.10 English VersionHeating systems in buildings - Method for calculation of systemenergy requirements and system efficiencies - Part 3-3:Domestic hot water systems, generationSystèmes de chauffage dans les bâtiments - Méthode decalcul des besoins énergétiques et des rendements dessystèmes - Partie 3-3 : Systèmes de production d'eauchaude sanitaire, générationHeizungsanlagen in Gebäuden - Verfahren zur Berechnungder Energieanforderungen und Nutzungsgrade der Anlagen- Teil 3-3: Trinkwassererwärmung, ErzeugungThis European Standard was approved by CEN on 18 August 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial 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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15316-3-3:2007: E
EN 15316-3-3:2007 (E) 2 Contents Page Foreword.4 Introduction.6 1 Scope.7 2 Normative references.7 3 Terms and definitions.7 4 Symbols, units and indices.10 5 Energy output of the domestic hot water generation sub-system.11 5.1 General.11 5.2 Domestic hot water systems with a single heat generator.11 5.3 Domestic hot water systems with multiple heat generators.12 5.3.1 General.12 5.3.2 Domestic hot water systems with different types of heat generators in a series configuration.12 5.3.3 Domestic hot water systems with multiple heat generators in a parallel configuration.12 6 Indirectly heated hot water storage vessel.13 7 Primary circulation pipes.14 7.1 General.14 7.2 Thermal losses by a simple estimation method.14 7.3 Thermal losses by a detailed calculation method.14 8 Direct heated domestic hot water generation devices.14 8.1 General.14 8.2 Heat generation systems in single-family dwellings.15 8.3 Heat generation systems others than for single-family dwellings.16 8.3.1 Oil and gas fired boilers.16 8.3.2 Direct gas fired domestic storage water heater.16 8.3.3 Direct electrical heated domestic storage water heaters.16 8.3.4 Alternative generators.17 9 Auxiliary energy.17 9.1 Total auxiliary energy consumption.17 9.2 Auxiliary energy consumption for primary circulation pumps.18 9.3 Auxiliary energy consumption for direct heated domestic hot water generation devices.18 10 Recoverable heat losses, recovered heat losses and unrecoverable heat losses.18 Annex A (informative)
Calculation of thermal loss from a gas or oil fired boiler
in systems other than for single family dwellings.20 A.1 Calculation of total boiler thermal loss.20 A.2 Calculation of heat loss during boiler operation.20 A.3 Calculation of stand-by heat loss.21 A.3.1 General.21 A.3.2 Average boiler temperature during a stand-by period.21 A.3.3 Load factor of a boiler.21 A.3.4 Auxiliary energy consumption for a boiler.22 A.3.5 Nominal output efficiency of a boiler.22 Annex B (informative)
Thermal loss from a gas fired domestic storage water heater.24 Annex C (informative)
Thermal loss from an electrical heated domestic
storage water heater (with continuous power on).26
EN 15316-3-3:2007 (E) 3 Annex D (informative)
Thermal loss from an electrical heated domestic storage water heater (with timed power on).27 Bibliography.31
EN 15316-3-3:2007 (E) 4 Foreword This document (EN 15316-3-3:2007) has been prepared by Technical Committee CEN/TC 228 “Heating systems in buildings”, the secretariat of which is held by DS. 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 2008, and conflicting national standards shall be withdrawn at the latest by April 2008. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive 2002/91/EC on the energy performance of buildings (EPBD). It forms part of a series of standards aimed at European harmonisation of the methodology for calculation of the energy performance of buildings. An overview of the whole set of standards is given in prCEN/TR 15615.' The subjects covered by CEN/TC 228 are the following: design of heating systems (water based, electrical etc.); installation of heating systems; commissioning of heating systems; instructions for operation, maintenance and use of heating systems; methods for calculation of the design heat loss and heat loads; methods for calculation of the energy performance of heating systems. Heating systems also include the effect of attached systems such as hot water production systems. All these standards are systems standards, i.e. they are based on requirements addressed to the system as a whole and not dealing with requirements to the products within the system. Where possible, reference is made to other European or International Standards, a.o. product standards. However, use of products complying with relevant product standards is no guarantee of compliance with the system requirements. The requirements are mainly expressed as functional requirements, i.e. requirements dealing with the function of the system and not specifying shape, material, dimensions or the like. The guidelines describe ways to meet the requirements, but other ways to fulfil the functional requirements might be used if fulfilment can be proved. Heating systems differ among the member countries due to climate, traditions and national regulations. In some cases requirements are given as classes so national or individual needs may be accommodated. In cases where the standards contradict with national regulations, the latter should be followed.
EN 15316-3-3:2007 (E) 5 EN 15316 Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies consists of the following parts: Part 1: General Part 2-1: Space heating emission systems Part 2-3: Space heating distribution systems Part 3-1: Domestic hot water systems, characterisation of needs (tapping requirements) Part 3-2: Domestic hot water systems, distribution Part 3-3: Domestic hot water systems, generation Part 4-1: Space heating generation systems, combustion systems (boilers) Part 4-2: Space heating generation systems, heat pump systems Part 4-3: Heat generation systems, thermal solar systems Part 4-4: Heat generation systems, building-integrated cogeneration systems Part 4-5: Space heating generation systems, the performance and quality of district heating and large volume systems Part 4-6: Heat generation systems, photovoltaic systems Part 4-7: Space heating generation systems, biomass combustion systems 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 United Kingdom.
EN 15316-3-3:2007 (E) 6 Introduction This European Standard is one of a number of standards that together describe methods for calculation of system energy requirements and system efficiencies related to domestic hot water systems. In particular this European Standard specifies methods for calculation of the input energy requirements and energy losses of the generation units. The user needs to refer to other European Standards or to national documents for input data and detailed calculation procedures not provided by this European Standard. Only the calculation methods are normative. Values necessary to complete the calculations should be given in a national annex.
EN 15316-3-3:2007 (E) 7 1 Scope This European Standard is part of a set of standards covering the methods for calculation of system energy requirements and system efficiencies of heating systems in buildings. In particular this standard is one of a number of standards dealing with domestic hot water systems. The scope of this specific part is to standardise the methods for calculation of: thermal losses from the domestic hot water generation system; recoverable thermal losses for space heating from the domestic hot water generation system; auxiliary energy of the domestic hot water generation systems. These values are input data for calculation of the overall energy use according to prEN 15603 and
EN 15316-1. This European Standard specifies the: inputs; calculation methods; outputs. 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 15316-3-2, Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies — Part 3-2 Domestic hot water systems, distribution prEN 50440, Efficiency of domestic electrical storage water-heaters 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 auxiliary energy electrical energy used by technical building systems for heating, cooling, ventilation and/or domestic hot water to support energy transformation to satisfy energy needs NOTE 1 This includes energy for fans, pumps, electronics etc. Electrical energy input to a ventilation system for air transport and heat recovery is not considered as auxiliary energy, but as energy use for ventilation. NOTE 2 In EN ISO 9488, the energy used for pumps and valves is called "parasitic energy". 3.2 building construction as a whole, including its envelope and all technical building systems, for which energy is used to condition the indoor climate, to provide domestic hot water and illumination and other services related to the use of the building
EN 15316-3-3:2007 (E) 8 NOTE The term can refer to the building as a whole or to parts thereof that have been designed or altered to be used separately. 3.3 calculation period period of time over which the calculation is performed NOTE The calculation period can be divided into a number of calculation steps. 3.4 domestic hot water heating process of heat supply to raise the temperature of the cold water to the intended delivery temperature 3.5 energy need for domestic hot water heat to be delivered to the needed amount of domestic hot water to raise its temperature from the cold network temperature to the prefixed delivery temperature at the delivery point, not taking into account the technical building thermal systems 3.6 energy use for space heating or cooling or domestic hot water energy input to the space heating or cooling system or the domestic hot water system to satisfy the energy need for space heating or cooling (including dehumidification) or domestic hot water, respectively NOTE If the technical building system serves several purposes (e.g. space heating and domestic hot water), it can be difficult to split the energy use into that used for each purpose. It can be indicated as a combined quantity (e.g. energy need for space heating and domestic hot water). 3.7 gross calorific value quantity of heat released by a unit quantity of fuel, when it is burned completely with oxygen at a constant pressure equal to 101 320 Pa, and when the products of combustion are returned to ambient temperature NOTE 1 This quantity includes the latent heat of condensation of any water vapour contained in the fuel and of the water vapour formed by the combustion of any hydrogen contained in the fuel. NOTE 2 According to ISO 13602-2, the gross calorific value is preferred to the net calorific value. NOTE 3 The net calorific value does not take into account the latent heat of condensation. 3.8 heating or cooling season period of the year during which a significant amount of energy for heating or cooling is needed NOTE The season lengths are used to determine the operation period of technical systems. 3.9 heat recovery heat generated by a technical building system or linked to a building use (e.g. domestic hot water) which is utilised directly in the related system to lower the heat input and which would otherwise be wasted (e.g. preheating of the combustion air by flue gas heat exchanger) 3.10 part load operation operation state of the technical system (e.g. heat pump), where the actual load requirement is below the actual output capacity of the device
EN 15316-3-3:2007 (E) 9 3.11 recoverable system thermal loss part of a system thermal loss which can be recovered to lower either the energy need for heating or cooling or the energy use of the heating or cooling system NOTE This depends on the calculation approach chosen to calculate the recovered gains and losses (holistic or simplified approach). 3.12 recovered system thermal loss part of the recoverable system thermal loss which has been recovered to lower either the energy need for heating or cooling or the energy use of the heating or cooling system 3.13 system boundary boundary that includes within it all areas associated with the building (both inside and outside the building) where energy is consumed or produced NOTE Inside the system boundary, the system losses are taken into account explicitly, outside the system boundary they are taken into account by the conversion factor. 3.14 system thermal loss thermal loss from a technical building system for heating, cooling, domestic hot water, humidification, dehumidification, or ventilation or lighting that does not contribute to the useful output of the system NOTE 1 A system loss can become an internal heat gain for the building, if it is recoverable. NOTE 2 Thermal energy recovered directly in the subsystem is not considered as a system thermal loss but as heat recovery and directly treated in the related system standard. NOTE 3 Heat dissipated by the lighting system or by other services (e.g. appliances of computer equipment) is not part of the system thermal losses, but part of the internal heat gains. 3.15 tapping program 24-hour cycle that defines a number of domestic hot water draw-off requirements: succession of energy needs corresponding to uses of domestic hot water during a day NOTE The tapping program is also called tapping cycle and tapping patterns. 3.16 technical building system technical equipment for heating, cooling, ventilation, domestic hot water, lighting and electricity production composed by sub-systems NOTE 1 A technical building system can refer to one or to several building services (e.g. heating system, space heating and domestic hot water system). NOTE 2 Electricity production can include cogeneration and photovoltaic systems. 3.17 technical building sub-system part of a technical building system that performs a specific function (e.g. heat generation, heat distribution, heat emission)
EN 15316-3-3:2007 (E) 10 4 Symbols, units and indices For the purposes of this document, the following symbols and units (Table 1) and indices (Table 2) apply. Table 1 — Symbols and units Symbol Name of quantity Unit A area m2 D diameter m L length m t time, period of time
s Q quantity of heat, energy
J P electrical power W V volume
m3 W auxiliary (electrical) energy
J x, y, z constants - ϕ load factor
. part - η efficiency
- θ celsius temperature
°C X coefficient of relative quantity of energy delivered versus maximum energy stored -
EN 15316-3-3:2007 (E) 11 Table 2 — Indices amb ambiant ls loss p pipe avg average max maximum sby
stand-by del delivered meas measured sol solar dis distribution mn arithmetic mean st storage e external nd need Tot total em emission nom nominal ve ventilation gen generation off off W domestic hot water in input to system on on x indices ind independent out output from system
int internal p primary
5 Energy output of the domestic hot water generation sub-system 5.1 General The heat generator for a domestic hot water system shall provide the energy required for meeting the energy need for domestic hot water and for compensating the losses in the other sub-systems (e.g. distribution). The energy requirement on the heat generator is given by: lspWlsstWlsdisWWoutgenWQQQQQ,,,,,,,,+++= (MJ/day)
(1) where outgenWQ,, is the total generation output (MJ/day); WQ
is the domestic hot water requirement (see EN 15316-3-1) (MJ/day); lsdisWQ,,
is the thermal loss from domestic hot water distribution system (see EN 15316-3-2) (MJ/day); lsstWQ,,
is the thermal loss from the domestic hot water storage vessel (if present) (MJ/day); lspWQ,,
is the thermal loss from primary pipes (if present) (MJ/day). If the heat generator or generators also provide space heating, the performance of the heat generator shall be calculated separately for operation during the summer period, when there is no space heating demand, and operation during the winter period, when both space heating and domestic hot water is being provided. 5.2 Domestic hot water systems with a single heat generator If a single heat generator is applied, the total generation output has to be provided from that heat generator.
EN 15316-3-3:2007 (E) 12 5.3 Domestic hot water systems with multiple heat generators 5.3.1 General If more than one heat generator is applied to provide the required heat energy for domestic hot water, the contribution from each heat generator is calculated on the basis of the nominal output of each individual heat generator. If any or all of these heat generators have separate primary pipe circuits, the primary pipe losses and the auxiliary energy consumption should be calculated separately for each circuit. 5.3.2 Domestic hot water systems with different types of heat generators in a series configuration If the domestic hot water is heated by different types of heat generators in a series configuration, the contribution of each individual heat generator shall be determined. Calculations are to be performed in the sequence of application of the heat generators for energy generation. NOTE Normally it is assumed, that the domestic hot water can be heated by a maximum of three heat generators: pre-heating by e.g. solar panels, base heating and supplementary heating to meet the peak load. If heat energy is supplied to the domestic hot water system from other types of appliances (e.g. exhaust air heat pump, see EN 15450 and prEN 15316-4-2), only the remaining heat demand is covered by the supplementary heat generator (e.g. a boiler). 5.3.3 Domestic hot water systems with multiple heat generators in a parallel configuration If more than one heat generator is applied in a parallel configuration to provide the required heat energy for domestic hot water, the proportional contribution igenW,,α of each unit is calculated from the ratio of the nominal output of that unit to the total nominal output of the installation available for heating the domestic hot water. outgenWiinomgenWinomgenWoutgenWigenWioutgenWQQQQQ,,,,,,,,,,,,,,,**∑==α (MJ/day) (2) For heating the domestic water, a number of heat generators (e.g. solar panel, boiler, heat pump, or electrical ancillary heating) can be available. The total heat requirement for all loads shall correspond to the total heat output of all heat generators: ∑∑=kjQQkin,dis,W,jout,gen,W, (MJ) (3) where joutgenWQ,,,
is the energy output of heat generator j during the time period considered (MJ); kindisWQ,,, is the energy input to the distribution system k during the time period considered (MJ). If more than one heat generator is applied, the total heat demand of the distribution system indisWQ,, is distributed amongst the available heat generators. The calculations are to be performed independently for each heat generator j on the basis of outgenWQ,, and jgenW,,α.
EN 15316-3-3:2007 (E) 13 6 Indirectly heated hot water storage vessel The storage thermal loss from an indirectly heated hot water storage vessel can be obtained from the stand-by heat loss of the vessel. The total heat dissipated from the storage vessel over the time period considered is quantified as a loss. The storage thermal loss is calculated from the stand-by heat loss with adjustment to actual temperature difference as follows: sbystWsbystWavgambavgstWlsstWQQ,,,,,,,,,)(∗∆−=θθθ (MJ/day) (4) where avgstW,,θ
is the average temperature of stored water (oC); avgamb,θ
is the average ambient temperature (oC); sbystW,,θ∆ is the average temperature difference applied at stand-by heat loss tests (oC); sbystWQ,,
is the stand-by heat loss (MJ/day). The weekly, monthly or annual thermal losses are obtained by multiplying the thermal loss per day by the appropriate number of days. The stand-by heat loss of the storage vessel has to be measured in accordance with a European Standard or national standard, e.g. EN 12897, appropriate for the vessel size and type. The measured stand-by heat loss is based on the actual temperatures during the period of operation. The standard to be used for the measurement shall be specified in a national annex. If the stand-by heat loss of the storage vessel is not available, a value can be calculated on the basis of an equation of the form; zstWsbystWVyxQ,,,∗+= (MJ/day) (5) where stWV,
is the volume per vessel (litres); zandyx,
are constants. Values for the constanst x, y and z shall be given in a national annex. The stand-by heat loss from older storage vessels can be estimated in a similar way, where values for the constants x, y and z shall also be given in a national annex. Alternatively, a national annex may specify the stand-by heat loss based on storage volume and insulation type and thickness. If the hot water storage vessel is located within the heated space of the building, part of the storage thermal loss may be recovered (see Clause 10). Connecting pipes to the storage water heater may increase the storage thermal loss, particularly if the pipes are not insulated. These additional losses are caused by circulation set up in the connecting pipes between
EN 15316-3-3:2007 (E) 14 the hot water in the storage vessel and cooler water in the pipes away from the vessel. If these losses are to be taken into account, the method shall be given in a national annex. 7 Primary circulation pipes 7.1 General Where the domestic hot water is supplied from an indirectly heated hot water storage vessel, the heat energy is supplied from a separate heat generator. The hot water storage vessel may be located adjacent to or remote from the heat generator. Thermal losses lspWQ,, occur from the primary circulation pipes between the heat generator and the hot water storage vessel, and these losses can be calculated by two different methods: a simple estimation method; a detailed calculation method. The hot water storage vessel may be incorporated into the heat generator appliance and thus the thermal loss of the primary circulation pipes may be taken into account by the overall appliance efficiency measurements. For gas appliances with a hot water storage vessel incorporated and intended to be installed in single family dwellings, measurements according to EN 13203-2 include the thermal loss of the primary circulation pipes. 7.2 Thermal losses by a simple estimation method A simple method for estimating the thermal losses from primary circulation pipes is to use a fixed representative value. For application of this method, appropriate values shall be given in a national annex. 7.3 Thermal losses by a detailed calculation method For this detailed calculation method the methods for calculation of thermal losses from pipes given in
EN 15316-3-2 shall be followed for the primary circulation pipes. Calculation of the thermal losses from the primary circulation pipes should be based on the actual length of the pipes, if available. If the detailed pipe network plan i
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