Heat exchangers - Test procedures for establishing performance of air to air heat recovery components

This European Standard specifies methods to be used for testing of air-to-air heat recovery components (HRC). The main purpose of the HRC shall be to
- preheat or heat and/or
- precool or cool
supply air in ventilation systems or air conditioning systems. Optional HRC can exchange air humidity between exhaust and supply air. The HRC contain the heat exchangers and all necessary features and auxiliary devices for the exchange of sensible heat and (if available) air humidity between exhaust air and supply air. The HRC will be installed in casings or air ducts. If fans are part of the test unit, the effect of the fan power on the measured values shall be corrected.
This European Standard specifies procedures and input criteria required for tests to determine the performance of a HRC at one or several test conditions, each of them with continuous air flows, air temperatures and humidities at both inlet sides. Three different test types are covered:
- Laboratory testing of HRC
- Laboratory testing of HRC installed in non-residential air handling
units (definition according Commission Regulation(EU) No 1253/2014) in design configuration
- On-site (field) testing of HRC in non-residential air handling units
or systems in operation configuration.
This European Standard is applicable to recuperators and regenerators intended for exchange of sensible heat and optionally for exchange of air humidity.
This European Standard prescribes test methods for determining:
1. the temperature and humidity efficiency
2. the pressure drop of exhaust air and supply air sides
3. possible internal leakages; exhaust air transfer ratio (EATR) and
outdoor air correction factor (OACF)and
4. auxiliary energy used for the operation of the HRC.
HRC using heat pumps are not covered by this standard.

Wärmeaustauscher - Prüfverfahren zur Bestimmung der Leistungskriterien von Luft/Luft-Wärmerückgewinnungsanlagen

Dieses Dokument legt Verfahren für die Prüfung von Luft-Luft-Wärmerückgewinnungskomponenten (HRC) fest. Der Hauptzweck der HRC besteht in dem Wärmeaustausch zwischen Fortluft und Zuluft, um Energie zu sparen. Dies führt zu
—   Vorerwärmung oder Erwärmung und/oder
—   Vorkühlung oder Kühlung von
Zuluft in Belüftungssystemen oder Klimaanlagen. Optional kann die HRC Luftfeuchtigkeit zwischen Fortluft und Zuluft austauschen. Die HRC enthält die Wärmeaustauscher und alle notwendigen Funktionen und Hilfsgeräte für den Austausch sensibler Wärme und (sofern verfügbar) Luftfeuchtigkeit zwischen Fortluft und Zuluft. Die HRC wird in Gehäusen oder Kanälen installiert. Wenn Ventilatoren Teil des Prüfgeräts sind, wird die Auswirkung der Ventilatorenleistung auf die Messwerte korrigiert.
Dieses Dokument legt Verfahren und Eingangskriterien für Prüfungen zur Bestimmung der Leistung einer HRC bei einer oder mehreren Prüfbedingungen fest, jeweils mit kontinuierlichen oder stationären Luftströmen, Lufttemperaturen und Feuchtewerten an beiden Eingangsseiten. Drei verschiedene Prüfarten werden behandelt:
—   Prüfart A, Laborprüfung von in Prüfgehäusen (A1) oder HRC-Abschnitten (A.2) installierten HRC;
—   Prüfart B, Laborprüfung von in Nichtwohnungsbelüftungsgeräten  in Bemessungskonfiguration installierten HRC;
—   Prüfart C, Vor-Ort-Prüfung (Feldprüfung) von HRC in Nichtwohnungsbelüftungsgeräten (C1) oder HRC-Abschnitten (C2) in Betriebskonfiguration.
Dieses Dokument gilt für Rekuperatoren, Regeneratoren und HRC mit intermediärem Wärmeübertragungsmedium.
Dieses Dokument schreibt Prüfverfahren für die Bestimmung:
1)   des Temperatur- und Feuchtewirkungsgrads;
2)   des Druckabfalls auf der Fortluft- und Zuluftseite;
3)   möglicher Innenleckage, des Fortluftübertragungsverhältnisses (EATR) und des Außenluft-korrekturfaktors (OACF);
4)   von Außenleckage und
5)   der für den Betrieb der HRC verwendeten Hilfsenergie vor.
HRC, die Wärmepumpe verwenden, werden in diesem Dokument nicht behandelt.

Échangeurs thermiques - Procédures d'essai pour la détermination de la performance des composants de récupération de chaleur air/air

Le présent document précise les méthodes à utiliser pour les essais sur les composants de récupération de chaleur air-air (HRC). L'objectif principal du HRC est d'échanger la chaleur entre l'air extrait et l'air neuf afin d'économiser l'énergie, ce qui se traduit par
—   le préchauffage ou chauffage, et/ou
—   le pré-refroidissement ou refroidissement
de l'air fourni dans les systèmes de ventilation ou de climatisation. Le cas échéant, les HRC peuvent échanger de l'humidité de l'air entre l'air extrait et l'air neuf. Le HRC contient les échangeurs thermiques et l'ensemble des fonctions et dispositifs auxiliaires nécessaires à l'échange de chaleur sensible et (si disponible) d'humidité de l'air entre l'air extrait et l'air neuf. Les HRC seront installés dans des enveloppes ou des conduits. Si les ventilateurs font partie de l'unité d'essai, l'effet de la puissance du ventilateur sur les valeurs mesurées sera corrigé.
Le présent document précise les procédures et les critères d'entrée requis pour les essais visant à déterminer la performance d'un HRC dans une ou plusieurs conditions d'essai, chacune d'entre elles ayant des flux d'air, des température et taux d'humidité de l'air continus et stationnaires des deux côtés d'entrée. Trois types d'essais différents sont traités :
—   Type d'essai A, essais en laboratoire du HRC installé dans des enveloppes d'essai (A1) ou dans des sections (A2) de HRC ;
—   Type d'essai B, essais en laboratoire du HRC installé dans des unités  de ventilation non résidentielles en configuration de conception ;
—   Essai de type C, essai sur site (sur le terrain) du HRC dans des unités de ventilation non résidentielles (C1) ou dans des sections (C2) de HRC en configuration de fonctionnement.
Le présent document s'applique aux récupérateurs, régénérateurs et HRC avec fluide intermédiaire.
Le présent document décrit des méthodes d'essai pour déterminer :
1)   le rendement en température et en humidité,
2)   la chute de pression côtés air extrait et air neuf,
3)   les fuites internes éventuelles ; le rapport de transfert d'air extrait (EATR) et le facteur de correction d'air extérieur (OACF),
4)   les fuites externes et
5)   l'énergie auxiliaire utilisée pour le fonctionnement du HRC.
Les HRC utilisant des pompes à chaleur ne sont pas couverts par le présent document.

Prenosniki toplote - Preskusni postopki za ugotavljanje lastnosti komponent za rekuperacijo toplote zrak-zrak

Ta evropski standard določa metode, ki se uporabljajo za preskušanje komponent za rekuperacijo toplote zrak-zrak (HRC). Glavni namen komponente za rekuperacijo toplote je:
– predgretje ali segrevanje in/ali
– predhodno hlajenje ali hlajenje
dovajanje zraka v prezračevalne ali klimatske sisteme. Izbirna komponenta za rekuperacijo toplote lahko izmenjuje vlažnost zraka med odvodnim in dovodnim zrakom. Komponenta za rekuperacijo toplote vsebuje toplotne izmenjevalnike in ima vse potrebne lastnosti ter pomožne naprave za izmenjavo zaznavne toplote in (če je na voljo) vlažnost zraka med odvodnim in dovodnim zrakom. Komponenta za rekuperacijo toplote se namesti v ohišja ali zračne kanale. Če so ventilatorji del preskusne enote, je treba popraviti učinek moči ventilatorja na izmerjene vrednosti.
Ta evropski standard določa postopke in vhodna merila, ki so potrebna za preskuse delovanja komponent za rekuperacijo toplote pri enem ali več preskusnih pogojih, pri vsakem od njih z neprekinjenimi zračnimi tokovi, temperaturami zraka in vlažnostjo na obeh vstopnih straneh. Zajete so tri različne vrste preskusov:
– laboratorijsko preskušanje komponent za rekuperacijo toplote;
– laboratorijsko preskušanje komponent za rekuperacijo toplote, nameščenih v nestanovanjskih klimatskih
napravah (opredelitev v skladu z Uredbo Komisije (EU) št. 1253/2014) v načrtovalni konfiguraciji;
– preskušanje delujočih komponent za rekuperacijo toplote na mestu uporabe (terensko) v nestanovanjskih klimatskih napravah
ali sistemih v obratovalni konfiguraciji.
Ta evropski standard se uporablja za rekuperatorje in regeneratorje, namenjene izmenjavi zaznavne toplote in po izbiri za izmenjavo vlažnosti zraka.
Ta evropski standard določa preskusne metode za določanje:
1. učinkovitosti temperature in vlažnosti,
2. padca tlaka odvodnega in dovodnega zraka,
3. morebitnega notranjega puščanja; razmerje prenosa odvodnega zraka (EATR) in
korekcijskega faktorja za zunanji zrak (OACF) ter
4. pomožne energije, ki se uporablja za delovanje komponent za rekuperacijo toplote.
Ta standard ne zajema komponent za rekuperacijo toplote, ki uporabljajo toplotne črpalke.

General Information

Status
Published
Public Enquiry End Date
02-Jun-2020
Publication Date
13-Apr-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
07-Apr-2022
Due Date
12-Jun-2022
Completion Date
14-Apr-2022

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 308:2022
01-junij-2022
Nadomešča:
SIST EN 308:1997
Prenosniki toplote - Preskusni postopki za ugotavljanje lastnosti komponent za
rekuperacijo toplote zrak-zrak
Heat exchangers - Test procedures for establishing performance of air to air heat
recovery components
Wärmeaustauscher - Prüfverfahren zur Bestimmung der Leistungskriterien von Luft/Luft-
Wärmerückgewinnungsanlagen
Échangeurs thermiques - Procédures d'essai pour la détermination de la performance
des composants de récupération de chaleur air/air
Ta slovenski standard je istoveten z: EN 308:2022
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
toplote
SIST EN 308:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 308:2022

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SIST EN 308:2022


EN 308
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2022
EUROPÄISCHE NORM
ICS 27.060.30 Supersedes EN 308:1997
English Version

Heat exchangers - Test procedures for establishing
performance of air to air heat recovery components
Échangeurs thermiques - Procédures d'essai pour la Wärmeaustauscher - Prüfverfahren zur Bestimmung
détermination de la performance des composants de der Leistungskriterien von Luft/Luft-
récupération de chaleur air/air Wärmerückgewinnungsanlagen
This European Standard was approved by CEN on 13 September 2021.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, 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: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 308:2022 E
worldwide for CEN national Members.

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SIST EN 308:2022
EN 308:2022 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
3.1 Air categories . 7
3.2 Thermal performance characteristics . 8
3.3 Air flow and leakage . 10
3.4 Pressure . 12
3.5 General terms and definitions . 13
3.6 Categories of heat recovery components . 13
3.7 Test types . 16
3.8 Uncertainty of measurement . 17
4 Symbols and abbreviations . 19
4.1 Symbols . 19
4.2 Subscripts . 21
4.3 Abbreviations . 21
5 Test requirements . 22
5.1 Specification of the-heat recovery components . 22
5.2 Precision classes . 22
5.3 Measurement equipment . 24
5.4 Determination of the air flow rates . 27
5.5 Test in laboratory . 28
5.6 Leakages . 30
5.7 Heat recovery components with run around coil system . 31
5.8 Uncertainty of the outdoor air correction factor . 31
6 Test procedures . 32
6.1 General. 32
6.2 Test type A . 49
6.3 Test type B . 53
6.4 Test type C . 56
7 Test Results . 57
7.1 Description of the heat recovery components concept, geometry and features . 57
7.2 Leakage . 59
7.3 Efficiency . 60
7.4 Pressure drop . 60
7.5 Other indications . 60
7.6 Reporting of values and precision . 60
7.7 Test report . 62
Annex A (informative) Testing equipment . 63
Annex B (informative) Deviation of different humidity definitions . 71
Annex C (normative) Uncertainty of measurement . 72
2

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SIST EN 308:2022
EN 308:2022 (E)
Annex D (informative) Estimation of Exhaust air transfer ratio . 78
Annex E (normative) Simplified test setup for static internal leakage . 81
Annex F (informative) Overviews of test procedures . 82
Bibliography . 86

3

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SIST EN 308:2022
EN 308:2022 (E)
European foreword
This document (EN 308:2022) has been prepared by Technical Committee CEN/TC 110 “Heat
exchangers”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2022, and conflicting national standards shall
be withdrawn at the latest by September 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 308:1997.
This edition includes the following significant technical changes with respect to EN 308:1997:
— Scope: flue gas heat recovery devices are no more included.
— In addition to laboratory tests of heat recovery components (HRC), laboratory tests for HRC fitted
into air handling units and on-site tests of HRC are defined.
— Different precision classes for tests are defined.
— Leakage testing has been refined. Exhaust air transfer ratio (EATR) and outdoor air correction factor
(OACF) are implemented.
— Differences of the sensible and latent efficiency can occur due to leakages and bad heat balance.
— Several terms and definitions are changed, e.g. categories of heat recovery components.
— Type A test is only on the heat exchanger and does not necessarily give a representative value when
it is installed, corrections may be needed.
EN 13053 refers to EN 308 regarding the test setup and the test procedure. EN 13053 is a standard
harmonized with the Commission Regulation (EU) 1253/2014 [5].
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
4

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SIST EN 308:2022
EN 308:2022 (E)
Introduction
This document specifies methods for the performance testing of air-to-air heat recovery components
(HRC) used in ventilation systems. This document does not contain any information on air handling units,
ductwork and components of air distribution, which are covered by other European Standards. The
document applies for laboratory and in on-site testing. Further it applies to different purposes of tests,
which can be e.g. certification of products, acceptance of installed products, market surveillance or quality
tests of manufacturers.
These different applications do not require the same precision of measurements results. Therefore,
different precision classes are defined. Table 1 gives informative examples for the application of the
different test types and precision classes. For low quality products, low quality installations and/or
simplified testing, a ‘not classified’ precision class can occur for all test types.
Table 1 — Examples for the application of the different test types and precision classes
Precision class P1 Precision class P2 Precision class P3 not classified
Test Type
(high precision) (medium precision) (low precision)
Test type A — certification or — test of — not intended use — not intended
declaration of functionality use
HRC installed in a test
products
casing or HRC-section
— performance test
Tested in laboratory
Test type B — test under ideal — certification or — test of — not intended
conditions declaration of functionality use
HRC installed in an
products
a
AHU
— performance test
Tested in laboratory

Test type C — not intended use, — test under ideal — typical test — test of
but possible conditions in real conditions in real functionality
HRC installed in an
under ideal systems systems
a
AHU or in duct work of
conditions and
— performance test
an installed ventilation
laboratory-like
system

test equipment
Tested on-site
a
  The HRC is installed in an AHU (air handling unit) by the manufacturer of the AHU.
Customers and manufacturers are free to define the aspired precision class for testing of their products,
but it will be taken into account that the available precision class depends on the test conditions, the HRC
itself, the measurement equipment and the environment conditions.
This document is one of a series of European Standards dedicated to heat exchangers.
Note 1 Testing procedure of residential ventilation units, RVU’s, is covered by EN 13141-7 and EN 13141-8.
Note 2 EN 13053 deals with non-residential ventilation units, NRVU’s, specifically Air Handling Units (AHU’s).
For testing of the heat recovery, EN 13053 refers to EN 308.
5

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SIST EN 308:2022
EN 308:2022 (E)
1 Scope
This document specifies methods to be used for testing of air-to-air heat recovery components (HRC).
The main purpose of the HRC is to exchange heat between exhaust air and supply air in order to save
energy, which results in
— preheat or heat, and/or
— precool or cool
supply air in ventilation systems or air conditioning systems. Optionally HRC can exchange air humidity
between exhaust and supply air. The HRC contains the heat exchangers and all necessary features and
auxiliary devices for the exchange of sensible heat and (if available) air humidity between exhaust air and
supply air. The HRC will be installed in casings or ducts. If fans are part of the test unit, the effect of the
fan power on the measured values will be corrected.
This document specifies procedures and input criteria required for tests to determine the performance
of a HRC at one or several test conditions, each of them with continuous and stationary air flows, air
temperatures and humidities at both inlet sides. Three different test types are covered:
— Test type A, Laboratory testing of HRC installed in test casings (A1) or a HRC sections (A2);
1
— Test type B, Laboratory testing of HRC installed in non-residential ventilation units in design
configuration;
— Test type C, on-site (field) testing of HRC in non-residential ventilation units (C1) or a HRC sections
(C2) in operation configuration.
This document is applicable to recuperators, regenerators, and HRC with intermediary heat transfer
medium.
This document prescribes test methods for determining:
1) the temperature and humidity efficiency,
2) the pressure drop of exhaust air and supply air sides,
3) possible internal leakages; exhaust air transfer ratio (EATR) and outdoor air correction factor
(OACF),
4) external leakages and
5) auxiliary energy used for the operation of the HRC.
HRC using heat pumps are not covered by this document.

1
Definition according Commission Regulation (EU) No 1253/2014 [5].
6

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SIST EN 308:2022
EN 308:2022 (E)
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1886, Ventilation for buildings — Air handling units — Mechanical performance
EN 13053, Ventilation for buildings — Air handling units — Rating and performance for units, components
and sections
JCGM 100, Evaluation of measurement data — Guide to the expression of uncertainty in measurement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Air categories
3.1.1
exhaust air inlet
air to be exhausted from the application, before entering the HRC
Note 1 to entry: In ventilation systems, this air is usually called extract air.
Note 2 to entry: Figure 1 shows the definition of the air flow categories in heat recovery components (HRC).

Key
11 Exhaust air inlet 22 Supply air outlet
12 Exhaust air outlet HRC Heat recovery component
21 Supply air inlet C Casing
Figure 1 — Air categories
3.1.2
exhaust air outlet
air in exhaust condition, intended to be blown back to the environment, after leaving the HRC
7

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SIST EN 308:2022
EN 308:2022 (E)
Note 1 to entry: In ventilation systems, this air is usually called exhaust air.
Note 2 to entry: See Figure 1.
3.1.3
supply air inlet
air intended for the application, before entering the HRC
Note 1 to entry: In ventilation systems, this air is usually called outdoor air. Sometimes this air does not come
directly from outdoor (preheated space, ground heat exchanger, etc.)
Note 2 to entry: See Figure 1.
3.1.4
supply air outlet
air intended for the application, after leaving the HRC
Note 1 to entry: See Figure 1.
3.2 Thermal performance characteristics
3.2.1
temperature efficiency
η
t,efy

transfer of sensible heat from exhaust to supply air, with correction of the temperature increase of the
supply air outlet caused by the EATR and a correction in case of a bad heat balance, to be used for the
description of the performance characteristic of a HRC
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: No definitions of temperature efficiency on the exhaust-air side are included. If data on the
exhaust-air side is required, conditions can be calculated by heat and mass balances, considering leakage and EATR.
Note 3 to entry: The temperature efficiency depends on the supply air mass flow and on the mass flow ratio
between the supply air flow and the exhaust air flow.
3.2.2
temperature gross efficiency
η
t,gro

temperature difference on the supply air side divided by the temperature difference between exhaust air
inlet and supply air inlet
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: The temperature gross efficiency does not regard internal or external leakages or heat flow
through the casing. The temperatures θ , θ and θ can differ from measured values, see 6.1.6.2.
11 21 22
Note 3 to entry: In Regulation (EU) 1253/2014 [5], the same equation is used. There, the definition is called
‘thermal efficiency of a non-residential HRS (η )’ and shall be measured under dry reference conditions, with
t_nrvu
balanced mass flows, an indoor-outdoor air temperature difference of 20 K, excluding thermal heat gain from fan
motors and from internal leakages.
8

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SIST EN 308:2022
EN 308:2022 (E)
3.2.3
temperature net efficiency
η

t,net
net transfer of sensible heat from exhaust to supply air, with correction of the temperature change of the
supply air outlet caused by the EATR
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: The temperature net efficiency does not regard external leakages or heat flow through the casing.
The temperatures θ , θ and θ can differ from measured values, see 6.1.6.2.
11 21 22
Note 3 to entry: Temperature net efficiency calculation is required if EATR is determined (see 5.5.2).
3.2.4
temperature effectiveness
ε

t
temperature gross efficiency, multiplied with the ratio of the mass flow rate of supply air outlet to the
minimum mass flow rate of supply outlet or exhaust air inlet
Note 1 to entry: The determination is according to 6.1.7.
Note 2 to entry: The temperature effectiveness describes the ratio of the effective sensible heat transfer from the
exhaust air side to the supply air side compared with the theoretical possible sensible heat transfer.
Note 3 to entry If the efficiency is very high, condensation occurs and the airflows are very unbalanced, the
effectiveness value can be higher than 1.
3.2.5
humidity efficiency
η

x,efy
transfer of latent heat from exhaust to supply air, with correction of the humidity change of the supply
air outlet caused by the EATR and a correction in case of a bad heat balance
Note 1 to entry: The humidity efficiency is determined according to 6.1.6.
Note 2 to entry: No definitions of humidity efficiency on the exhaust-air side are included. If data on the exhaust-
air side is required, conditions can be calculated by heat and mass balances, considering leakage and EATR.
Note 3 to entry: The humidity efficiency depends on the supply air flow and on the mass flow ratio between the
supply air flow and the exhaust air flow.
3.2.6
humidity gross efficiency
η

x,gro
absolute humidity difference on the supply air side divided by the absolute humidity difference between
exhaust air inlet and supply air inlet
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: No definitions of efficiency on the exhaust-air side are included. If data on the exhaust-air side is
required, conditions can be calculated by mass balances, considering leakages.
9

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SIST EN 308:2022
EN 308:2022 (E)
3.2.7
humidity net efficiency
η

x, net
net transfer of latent heat exhaust to supply air, with correction of the humidity change of the supply air
outlet caused by the EATR
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: Humidity net efficiency calculation is required if EATR is determined (see 5.5.2).
3.2.8
humidity effectiveness
ε

x
humidity efficiency, multiplied with the ratio of the dry mass flow rate of supply air outlet to the minimum
dry mass flow rate of supply outlet or exhaust air inlet
Note 1 to entry: The determination is according to 6.1.7.
3.3 Air flow and leakage
3.3.1
nominal leakage rate
ratio of the leakage (air volume flow) to the nominal air volume flow, at standard conditions
3.3.2
external leakage
q
ve
leakage from casing to or from the ambient air
Note 1 to entry: The external leakage is usually measured under static pressure difference. For calculations
considering the impact of the external leakage on measurement uncertainty, the external leakage in operational
mode has to be determined usually by calculation or estimation.
3.3.3
internal leakage
q
vi
umbrella term for the following definitions:
— test setup leakage;
— static internal leakage;
— dynamic internal leakage
3.3.4
test setup internal leakage
q
vi,setup
internal leakage of the test casing for Test Type A1, measured with static pressure difference
10

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SIST EN 308:2022
EN 308:2022 (E)
3.3.5
static internal leakage
q
vi,stat
internal leakage of the unit under test, measured with static pressure difference
Note 1 to entry: The static internal leakage is used as quality indicator for a HRC, where EATR and OACF are not
determined. This concerns constructions with no or only minor leakages, such as plate heat exchangers.
Note 2 to entry: The unit under test is defined by the test type.
3.3.6
dynamic internal leakage
internal leakage of the HRC, measured in operation conditions with air flow on both sides
Note 1 to entry: The dynamic internal leakage is characterized by EATR and OACF. EATR and OACF shall be
declared as a pair at identical conditions.
3.3.7
air flow
mass flow and volume flow of air
Note 1 to entry: If a clarification (mass or volume) is necessary the term is complemented with the applicable
symbol.
Note 2 to entry: Used as an umbrella term.
3.3.8
exhaust air transfer ratio
EATR
transfer of exhaust air into the supply air side in HRC and which provides information on the ratio of
exhaust air in the supply air
Note 1 to entry: The EATR can be measured with tracer gas. The determination is according to 6.1.2.
Note 2 to entry: The subscript shows how the EATR is determined or measured respectively:
— EATR : According to Test Type A1
A1
— EATR : According to Test Type A2
A2
— EATR : According to Test Type B
B
— EATR : According to Test Type C
C
Note 3 to entry: The EATR depends on pressure difference and airflows. Therefore, the test conditions at which
EATR is determined always have to be declared.
Note 4 to entry: Procedures for the estimation of the EATR for test type C are described in Annex D.
Note 5 to entry: EATR replaces the old term Carry-Over.
11

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EN 308:2022 (E)
3.3.9
outdoor air correction factor
OACF
ratio of the entering supply mass airflow rate and the leaving supply mass airflow rate, which provides
information about the leakages between the air flows
Note 1 to entry: The determination is according to 6.1.2.
Note 2 to entry: The OACF depends on pressure difference and airflows. Therefore, the test conditions at which
OACF is determined always have to be declared.
3.3.10
mass flow rate exhaust air inlet
q
m11
air mass flow on the exhaust air inlet side
Note 1 to entry: This is the mass flow that leaves the application side.
3.3.11
mass flow rate exhaust air outlet

q
m12
air mass flow on the exhaust air outlet side
3.3.12
mass flow rate supply air inlet
q
m21
air mass flow on the supply air inlet side
3.3.13
mass flow rate supply air outlet
q
m22
air mass flow on the supply air outlet side
Note 1 to entry: This is the mass flow that enters the application side.
3.3.14
nominal air mass flow rate
q
m,n
declared air mass flow rate as base for testing and test results
3.4 Pressure
3.4.1
pressure difference 22−11
Δp
22−11
difference in static pressure between the supply air outlet and the exhaust air inlet, measured in the
casing or other connections with the same cross section area on both sides
Note to entry: The pressure difference is determined according 6.1.4.1.
12

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EN 308:2022 (E)
3.4.2
pressure drop
Δp , Δp
11−12 21−22
loss in static pressure between the inlet and the outlet of a HRC, measured in the casing or other
connections with the same cross section area on both sides
Note to entry: The pressure drop is determined according 6.1.4.2.
3.4.3
external static pressure difference
Δp
s,ext
difference between the static pressure at the outlet of the air handling unit and the static pressure at the
inlet
[SOURCE: EN 13053]
3.4.4
static internal leakage mass flow rate
q
m,il,stat
leakage, caused by a static pressure difference between exhaust air side and supply air side
Note 1 to entry: Measured by blanking off and sealing all ducts of the HRC or HRC section.
3.5 General terms and definitions
3.5.1
standard air conditions
3
relating to air with a density of 1,20 kg/m , at a temperature of 20 °C, an atmospheric air pressure of
101 325 Pa and a relative humidity 40 %
3.5.2
face area
A
f22
orthographic projection of the supply air outlet side of the HRC, which is in contact with the supply air
Note 1 to entry: The face area of HRC depends on the HRC category and construction.
3.6 Categories of heat recovery components
3.6.1
heat recovery component
HRC
heat exchanger or combinations of heat exchangers which transfer heat and, in some cases humidity,
between exhaust and supply air flow depending on the difference of temperature and humidity levels and
which are gen
...

SLOVENSKI STANDARD
oSIST prEN 308:2020
01-maj-2020
Prenosniki toplote - Preskusni postopki za ugotavljanje lastnosti naprav za prenos
toplote zrak/zrak in dimni plini/zrak
Heat exchangers - Test procedures for establishing performance of air to air and flue
gases heat recovery devices
Wärmetauscher - Prüfverfahren zur Bestimmung der Leistungskriterien von Luft-Luft-
Wärmrückgewinnungs-komponenten
Echangeures thermique - Procedures d’essai pour la determination de la performance
des recuperateurs de chaleur air/air
Ta slovenski standard je istoveten z: prEN 308
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
toplote
oSIST prEN 308:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 308:2020

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oSIST prEN 308:2020


DRAFT
EUROPEAN STANDARD
prEN 308
NORME EUROPÉENNE

EUROPÄISCHE NORM

May 2020
ICS Will supersede EN 308:1997
English Version

Heat exchangers - Test procedures for establishing
performance of air to air and flue gases heat recovery
devices
Echangeures thermique - Procedures d'essai pour la Wärmetauscher - Prüfverfahren zur Bestimmung der
determination de la performance des recuperateurs de Leistungskriterien von Luft-Luft-
chaleur air/air Wärmrückgewinnungs-komponenten
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 110.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 308:2020 E
worldwide for CEN national Members.

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oSIST prEN 308:2020
prEN 308:2020 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
3.1 Air categories . 7
3.2 Thermal performance characteristics . 8
3.3 Leakage and mass flow . 12
3.4 Pressure . 16
3.5 General terms and definitions . 17
3.6 Categories of heat recovery components . 18
3.7 Test types . 20
3.8 Uncertainty of measurement . 22
3.8.1 Expression of uncertainty . 22
4 Symbols and abbreviations . 23
4.1 Symbols . 23
4.2 Subscripts . 25
4.3 Abbreviations . 26
5 Test requirements . 26
5.1 Specification of the HRC . 26
5.2 Precision classes . 26
5.3 Measurement equipment . 27
5.3.1 Uncertainties of probes and measurement instruments . 27
5.3.2 Temperature measuring plane . 28
5.3.3 Measurement of pressure drop and pressure differences . 30
5.3.4 Determination of the air flow rates . 30
5.4 Test in laboratory . 31
5.4.1 General. 31
5.4.2 Atmospheric pressure . 31
5.4.3 Ambient conditions . 31
5.4.4 Test casings . 32
5.5 Leakages . 33
5.5.1 General. 33
5.5.2 Internal leakage test . 33
5.6 Specific HRC categories . 33
5.6.1 Category HRC2a . 33
6 Test procedures . 34
6.1 General. 34
6.1.1 Overview . 34
6.1.2 Leakage test . 34
6.1.3 Pressure drop test . 37
6.1.4 Conditions for leakage and pressure drop measurements . 37
6.1.5 Efficiency test . 38
6.1.6 Calculation of the efficiency . 43
2

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6.2 Test type A . 46
6.2.1 Preparation of the HRC . 46
6.2.2 Leakage test . 46
6.2.3 Pressure drop tests . 48
6.2.4 Efficiency test . 48
6.2.5 Calculation of the efficiency . 49
6.3 Test type B . 49
6.3.1 Setting of the AHU . 49
6.3.2 Setting of the design operation point . 49
6.3.3 Leakage test . 51
6.3.4 Pressure drop test . 52
6.3.5 Efficiency test . 52
6.3.6 Calculation of the efficiency . 52
6.4 Test type C . 52
6.4.1 Preparation of the HRC . 52
6.4.2 Leakage test . 53
6.4.3 Efficiency tests . 53
6.4.4 Pressure drop test . 54
7 Test Results . 54
7.1 Description of HRC concept, geometry and features . 54
7.1.1 General . 54
7.1.2 Face air velocity . 54
7.1.3 Plate heat exchanger . 54
7.1.4 Rotary HRC . 55
7.1.5 HRC with intermediary heat transfer medium . 55
7.1.6 Other constructions . 55
7.2 Leakage. 55
7.3 Efficiency . 56
7.3.1 Temperature and humidity efficiency . 56
7.3.2 Electric power input and speed . 56
7.3.3 Heat balance and precision class . 56
7.4 Pressure drop . 56
7.5 Other indications . 57
7.6 Reporting of values and precision . 57
7.7 Test report . 58
Annex A (informative) Testing equipment . 59
Annex B (informative) Deviation of different humidity definitions . 66
Annex C (normative) Uncertainty of measurement . 67
Annex D (informative) Estimation of EATR . 72
Annex E (normative) Simplified test setup for static internal leakage . 74
Annex F (informative) Alternative method for OACF measurement . 75
Annex G (informative) Overviews of test procedures . 77
Bibliography . 81

3

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oSIST prEN 308:2020
prEN 308:2020 (E)
European foreword
This document (prEN 308:2020) has been prepared by Technical Committee CEN/TC 110 “Heat
exchangers”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 308:1997.
This edition includes the following significant technical changes with respect to EN 308:1997:
— Scope: flue gas heat recovery devices are no more included.
— In addition to laboratory tests of heat recovery components (HRC), laboratory tests for HRC fitted
into air handling units and on-site tests of HRC are defined.
— Different precision classes for tests are defined.
— Leakage testing has been refined. Exhaust air transfer ration (EATR) and outdoor air correction
factor (OACF) are implemented.
— Correction of the sensible and latent efficiency due to leakages and bad heat balance are
implemented.
— Several terms and definitions are changed, e.g. categories of heat recovery components.
EN 13053 refers to EN 308 regarding the test setup and the test procedure. EN 13053 is a standard
harmonized with the Commission Regulation (EU) 12353/2014 [6].
4

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prEN 308:2020 (E)
Introduction
This document specifies methods for the performance testing of air-to-air heat recovery components
(HRC) used in ventilation systems. This document does not contain any information on air handling
units, ductwork and components of air distribution, which are covered by other European Standards.
The document applies for laboratory and in on-site testing. Further it applies to different purposes of
tests, which can be e.g. certification of products, acceptance of installed products, market surveillance
or quality tests of manufacturers. These different applications do not require the same precision of
measurements results. Therefore, different precision classes are defined. Table 1 gives informative
examples for the application of the different test types and precision classes. For low quality products,
low quality installations and/or simplified testing, a ‘not classified’ precision class can occur for all test
types.
Table 1 — Examples for the application of the different test types and precision classes
Examples for the application for precision class
Test Type
Precision class P1 Precision class P2 Precision class P3 not classified
(high precision) (medium precision) (low precision)
Test type A — certification of — internal tests, e.g. for — special test points — not intended
products R&D under extreme use
HRC installed in a test
conditions
casing or HRC-section — quality tests before
market launch — test of functionality
Tested in laboratory
Test type B — test under ideal — certification of — internal tests, e.g. — not intended
conditions with products for R&D use
a
HRC installed in an AHU
high-quality
— quality tests before — test of functionality
Tested in laboratory
products
market launch
Test type C — not intended use, — test under ideal — typical test — test of
but possible under conditions in real conditions in real functionality
a
HRC installed in an AHU
ideal conditions systems systems
or in duct work of an
with high-quality
installed ventilation
products and
system
laboratory-like test
Tested on-site
equipment
a
The HRC is installed in an AHU (air handling unit) by the manufacturer of the AHU.
Customers and manufacturers are free to define the aspired precision class for testing of their products,
but it will be taken into account that the available precision class depends on the test conditions, the
HRC itself, the measurement equipment and the environment conditions.
This document is one of a series of European Standards dedicated to heat exchangers.
NOTE 1 Testing procedure of residential ventilation units, RVU’s, is covered by EN 13141-7 and EN 13141-8.
NOTE 2 EN 13053 deals with non-residential ventilation units, NRVU’s, specifically Air Handling Units (AHU’s).
For testing of the heat recovery, EN 13053 refers to EN 308.
5

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prEN 308:2020 (E)
1 Scope
This document specifies methods to be used for testing of air-to-air heat recovery components (HRC).
The main purpose of the HRC is to exchange heat between exhaust air and supply air in order to save
energy, which results in
— preheat or heat, and/or
— precool or cool
supply air in ventilation systems or air conditioning systems. Optionally HRC can exchange air humidity
between exhaust and supply air. The HRC contains the heat exchangers and all necessary features and
auxiliary devices for the exchange of sensible heat and (if available) air humidity between exhaust air
and supply air. The HRC will be installed in casings or ducts. If fans are part of the test unit, the effect of
the fan power on the measured values will be corrected.
This document specifies procedures and input criteria required for tests to determine the performance
of a HRC at one or several test conditions, each of them with continuous and stationary air flows, air
temperatures and humidities at both inlet sides. Three different test types are covered:
— Test type A, Laboratory testing of HRC installed in test casings (A1) or a HRC sections (A2);
1
— Test type B, Laboratory testing of HRC installed in non-residential ventilation units in design
configuration;
— Test type C, On-site (field) testing of HRC in non-residential ventilation units (C1) or a HRC sections
(C2) in operation configuration.
This document is applicable to recuperators, regenerators, and HRC with intermediary heat transfer
medium.
This document prescribes test methods for determining:
1) the temperature and humidity efficiency,
2) the pressure drop of exhaust air and supply air sides,
3) possible internal leakages; exhaust air transfer ratio (EATR) and outdoor air correction factor
(OACF),
4) external leakages and
5) auxiliary energy used for the operation of the HRC.
HRC using heat pumps are not covered by this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1886, Ventilation for buildings - Air handling units - Mechanical performance

1
Definition according Commission Regulation (EU) No 1253/2014 [6]
6

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oSIST prEN 308:2020
prEN 308:2020 (E)
EN 13053:2019, Ventilation for buildings - Air handling units - Rating and performance for units,
components and sections
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Air categories
3.1.1
exhaust air inlet
air to be exhausted from the application, before entering the HRC
Note 1 to entry: In ventilation systems, this air is usually called extract air.
Note 2 to entry: See Figure 1.

Key
11 Exhaust air inlet
12 Exhaust air outlet
21 Supply air inlet
22 Supply air outlet
HRC Heat recovery component
C Casing
NOTE Figure 1 shows the definition of the air flow categories in heat recovery components (HRC).
Figure 1 — Air categories
3.1.2
exhaust air outlet
air in exhaust condition, intended to be blown back to the environment, after leaving the HRC
Note 1 to entry: See Figure 1.
7

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oSIST prEN 308:2020
prEN 308:2020 (E)
3.1.3
supply air inlet
air intended for the application, before entering the HRC
Note 1 to entry: In ventilation systems, this air is usually called outdoor air. Sometimes this air does not come
directly from outdoor (preheated space, ground heat exchanger, etc.)
Note 2 to entry: See Figure 1.
3.1.4
supply air outlet
air intended for the application, after leaving the HRC
Note 1 to entry: See Figure 1.
3.2 Thermal performance characteristics
3.2.1
temperature efficiency
η
t,efy
transfer of sensible heat from exhaust to supply air, with correction of the temperature increase of the
supply air outlet caused by the EATR and a correction in case of a bad heat balance
Note 1 to entry: The determination is according to 6.1.6.
Note 2 to entry: This term shall be used to describe the performance characteristic of a HRC for sensible heat.
Note 3 to entry: No definitions of temperature efficiency on the exhaust-air side are included. If data on the
exhaust-air side is required, conditions can be calculated by heat and mass balances, considering leakage and
EATR.
Note 4 to entry: The temperature efficiency depends on the mass flow and on the mass flow ratio between the
supply air flow and the exhaust air flow.
8

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3.2.2
temperature gross efficiency
η
t,gro
temperature difference on the supply air side divided by the temperature difference between exhaust
air inlet and supply air inlet
Note 1 to entry: The temperature gross efficiency is calculated as in Formula (1).
θθ−
22 21
η = (1)
t,gro
θθ−
11 21
where
θ is temperature of exhaust air inlet, in °C;
11
θ is temperature of supply air inlet, in °C;
21
θ is temperature of supply air outlet, in °C.
22
Note 2 to entry: The temperature gross efficiency does not regard internal or external leakages or heat flow
through the casing. The temperatures θ , θ and θ can differ from measured values, see 6.1.6.2.
11 21 22
Note 3 to entry: In Regulation (EU) 1253/2014 [6], the same equation is used. There, the definition is called
‘thermal efficiency of a non-residential HRS (η )’ and shall be measured under dry reference conditions, with
t_nrvu
balanced mass flows, an indoor-outdoor air temperature difference of 20 K, excluding thermal heat gain from fan
motors and from internal leakages.
3.2.3
temperature net efficiency
η
t,net
net transfer of sensible heat from exhaust to supply air, with correction of the temperature change of
the supply air outlet caused by the EATR
Note 1 to entry: The temperature net efficiency is calculated as in Formula (2).
θθ−⋅EATR
22 11
−θ
21
1− EATR
η = (2)
t net
,
θθ−
11 21
where
EATR
is exhaust air transfer ratio;
θ is temperature of exhaust air inlet, in °C;
11
θ is temperature of supply air inlet, in °C;
21
θ is temperature of supply air outlet, in °C.
22
Note 2 to entry: The temperature net efficiency does not regard external leakages or heat flow through the casing.
The temperatures θ , θ and θ can differ from measured values, see 6.1.6.2.
11 21 22
Note 3 to entry: Temperature net efficiency calculation is required if EATR is determined (see 5.5.2)
9

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3.2.4
temperature effectiveness
η
t,efs
temperature gross efficiency, multiplied with the ratio of the mass flow rate of supply air outlet to the
minimum mass flow rate of supply outlet or exhaust air inlet
Note 1 to entry: The temperature effectiveness is calculated as in Formula (3).
q ⋅θθ−
( )
m22 22 21
η = (3)
t,efs
q ⋅θθ−
( )
m,min 11 21
where
is mass flow rate of supply air outlet, in kg/s
q
m22
is minimum mass flow rate, either of supply air outlet or exhaust air inlet, in kg/s
q
m,min
q = min qq,
( )
m,min m22 m11
θ is temperature of exhaust air inlet, in °C
11
θ is temperature of supply air inlet, in °C
21
θ is temperature of supply air outlet, in °C
22
Note 2 to entry: The temperature effectiveness describes the ratio of the effective sensible heat transfer from the
exhaust air side to the supply air side compared with the theoretical possible sensible heat transfer.
3.2.5
humidity efficiency
η
x,efy
transfer of latent heat from exhaust to supply air, with correction of the humidity change of the supply
air outlet caused by the EATR and a correction in case of a bad heat balance
Note 1 to entry: The humidity efficiency is de
...

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