EN 16905-2:2026
(Main)Gas-fired endothermic engine driven heat pumps - Part 2: Safety
- Abstract
This part of EN 16905 specifies the safety requirements, the safety test conditions and the safety test methods of gas-fired endothermic engine driven heat pumps for heating and/or cooling mode including the engine heat recovery, to be used outdoors.
This document specifies minimum operating requirements which ensure that the products are fit for the use designated by the manufacturer when used for space heating and/or cooling.
This document is used in conjunction with:
a) the terms and conditions, EN 16905-1:2023;
b) the test conditions, EN 16905-3:2024;
c) the test methods, EN 16905-4:2026;
d) the calculation of seasonal performances in heating and cooling mode, EN 16905-5:2022;
e) the heat pump, EN 14511-4:2022, EN 378-1:2016+A1:2020, EN 378-2:2016, EN 378 3:2016+A1:2020, EN 378-4:2016+A1:2019 and EN 14825:2022;
f) electrical safety, EN 60335-1:2012, EN 60335-2-102:2016, EN 60335-2-40:2003 and EN 60204 1:2018.
This document only applies to GEHP appliances with a maximum heat input (based on net calorific value) not exceeding 70 kW at standard rating conditions.
This document only applies to GEHP appliances under categories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P and II2Er3P according to EN 437:2021.
This document only applies to GEHP appliances:
a) that have gas fired endothermic engines under the control of fully automatic control systems;
b) that have closed system refrigerant circuits in which the refrigerant does not come into direct contact with the fluid to be cooled or heated;
c) where the temperature of the heat transfer fluid of the heating system (heating water circuit) does not exceed 105 °C during normal operation;
d) where the maximum operating pressure in the:
1) heating water circuit (if installed) does not exceed 6 bar;
2) domestic hot water circuit (if installed) does not exceed 10 bar.
This document is applicable to GEHP appliances only when used for space heating or space cooling or for refrigeration, with or without heat recovery.
NOTE This document provides requirements for GEHP appliances with known constructions. For GEHP appliances with any alternative constructions, which are not fully be covered by this standard, the risk associated with this alternative construction needs to be assessed.
- Status
- Published
- Publication Date
- 08-Sep-2026
- Technical Committee
- CEN/TC 299 - Gas-fired sorption appliances and domestic gas-fired washing and drying appliances
- Drafting Committee
- CEN/TC 299/WG 3 - Gas-fired endothermic engine heat pumps
- Current Stage
- 6060 - Definitive text made available (DAV) - Publishing
- Start Date
- 09-Sep-2026
- Due Date
- 27-Dec-2022
- Completion Date
- 09-Sep-2026
EN 16905-2:2026 is a CEN standard for the safety of gas-fired endothermic engine driven heat pumps (GEHP appliances) used outdoors. It specifies safety requirements, safety test conditions and safety test methods for appliances used for space heating, space cooling and refrigeration, including engine heat recovery. It is written for manufacturers, test labs, installers and others who need to know what a GEHP appliance has to meet before it is put into service.
What does EN 16905-2:2026 specify?
EN 16905-2:2026 defines the safety part of the EN 16905 series for GEHP appliances. The scope limits the standard to outdoor appliances with a maximum heat input of 70 kW at standard rating conditions, closed refrigerant circuits, fully automatic control systems, and specified water-side temperature and pressure limits.
EN 16905-2:2026 is intended to be used together with the companion parts of EN 16905 and with related heat pump, refrigerant and electrical safety standards. The document is organized into clauses for scope, references, terms, classification, design requirements, operational requirements, test methods, risk assessment, marking and instructions, followed by annexes for emissions calculations, test methods, marking examples and EU regulatory relationships.
| Annex | What it covers |
|---|---|
| A | Calculation of conversion of NO |
| B | Engine startup test method |
| C | CO concentration test method |
| D | NO concentration test method |
| E | Power failure test method |
| F | Examples for marking |
| G | Examples for NO calculation |
| ZA | Relationship with Commission Regulation (EU) No 2016/426 |
| ZB | Relationship with Commission Regulation (EU) No 813/2013 |
| ZC | Relationship with Commission Regulation (EU) No 2016/2281 |
What are the key requirements of EN 16905-2:2026?
EN 16905-2:2026 is mainly a safety design and type-test standard. The most important points are the product limits, the mechanical and electrical safety features, the operating checks, the emission limits, and the marking and instruction rules that support safe installation and use.
Scope and product classification
Clause 4 classifies GEHP appliances by gas family, unit structure, air blowing system and maximum water-side operating pressure (PMS). The gas categories are limited to gas families 2 and 3, and the pressure classes are based on PMS at 1 bar, 3 bar, or above 3 bar up to 6 bar. In practice, a user or buyer has to check that the appliance category, gas supply and water-side pressure match the intended installation.
Safe design of the appliance
Clause 5.1 requires the structure to protect people and control unsafe gas or refrigerant behaviour. The standard calls for smooth accessible edges, weather protection for control and electrical parts, guarded moving parts, fire-resistant insulation near electrical parts, drainability for condensate, and gas supply control with automatic start, monitoring and shut-off.
A key gas safety measure is the use of two or more automatic shut-off valves in series, each with independent function. The gas carrying circuit, engine safety system and combustion products circuit must be designed so that unburned gas does not accumulate and unsafe operation stops the gas supply.
Material and component requirements
Clause 5.2 sets material rules for the domestic hot water circuit, gas carrying circuit, combustion products circuit, insulation around the engine, and pressure-bearing water-side parts. The standard points to corrosion resistance, pressure resistance and compatibility with gas, condensate and water.
For pressure class 3 parts, the document includes material properties, minimum wall thicknesses and weld requirements in tables. In practice, this means the manufacturer must choose suitable metals, thicknesses and weld types, and keep supporting design records for pressure parts.
Electrical and EMC safety
Clause 5.3 requires compliance with EN 60335-2-102 for risks based on electrical energy, and with the listed EMC standards as far as applicable. This matters because a GEHP appliance combines gas combustion, rotating machinery and electrical control, so electrical failure or electromagnetic disturbance must not create a safety hazard.
Operational checks and limit values
Clause 6 sets the measurable safety performance. It covers soundness of the gas, water and internal cooling circuits, heat input at standard rating conditions, limit temperatures, starting and maximum operating conditions, insulation resistance, transient overvoltage, withstand voltage, waterproof performance, sound power level, engine behaviour, ignition safety, power failure behaviour, abnormality response and starting current.
Some of the key acceptance values are:
- gas leakage limits for soundness testing
- heat input not more than 105% of declared value, with a 500 W or 10% tolerance rule
- waterproof protection to IP X4
- sound power level limits by capacity, up to 88 dB for the highest range
- CO concentration limits of 1 000 ppm in standard and limit conditions, and 2 000 ppm in special conditions
- NO emissions limited to 240 mg/kWh fuel input in terms of GCV
- Maximum Ignition Safety Time (TSA max) under 20 s
- Extinction safety time not over 5 s
- up to 5 recycling attempts
- starting current below the declared value or 60 A if no value is stated
In practice, these are the type-test results that show whether the appliance starts, runs, protects itself and shuts down safely.
Risk assessment, marking and instructions
Clause 8 requires a manufacturer risk assessment for technical solutions not already covered by the standard or other harmonized standards. Clause 9 then requires durable marking, installation instructions, user instructions and gas conversion instructions. This is what ties the technical design to real-world installation: the installer needs the gas setting, pressure, electrical data, water data, refrigerant data, warnings and servicing information in a form that can be used on site.
What terms does EN 16905-2:2026 define?
EN 16905-2:2026 defines several terms in Clause 3 and uses the terms from EN 16905-1.
- GEHP appliance - a gas-fired endothermic engine driven heat pump used in the applications covered by the standard.
- PMS - maximum water operating pressure, stated in bar, used to classify the water-side pressure capability of the appliance.
- TSA - Ignition Safety Time, meaning the time between gas supply start and stop when ignition does not take place.
- TSA max - Maximum Ignition Safety Time measured under the least favourable ambient temperature and supply voltage.
- Single split - one GEHP appliance combined with one heating/cooling device to form a matched unit.
- Multi split - one GEHP appliance with one refrigerant circuit combined with multiple heating/cooling devices.
- Non ducted type - air is taken from and discharged into the same space.
- Ducted type - air is taken from one space and discharged outside that space.
Who uses EN 16905-2:2026?
EN 16905-2:2026 is used by GEHP appliance manufacturers, design engineers, type-test laboratories, certification bodies, installers and maintenance professionals. It is also relevant to quality managers and buyers who need to confirm that a product is suitable for outdoor space heating, space cooling or refrigeration within the stated limits.
In practice, users apply it when selecting gas category, pressure class and installation conditions; preparing type tests; writing installation and user instructions; marking the product; and documenting risk assessments for designs that go beyond the known constructions covered by the standard.
What changed in EN 16905-2:2026 from the previous edition?
The foreword states that this edition supersedes EN 16905-2:2020. It also says that editorial and technical changes were made throughout the document, including Annex ZA, Annex ZB and Annex ZC, to align the text with the ecodesign requirements stated in Commission Regulation (EU) No 2016/426.
Which standards are used with EN 16905-2:2026?
EN 16905-2:2026 is meant to be used with the other parts of EN 16905 and with standards covering heat pumps, refrigerants, gas equipment, electrical safety, EMC, sound power and marking.
| Standard | Contribution |
|---|---|
| EN 16905-1:2023 | Terms and conditions for the EN 16905 series |
| EN 16905-3:2024 | Test conditions |
| EN 16905-4:2026 | Test methods |
| EN 16905-5:2022 | Seasonal performance calculation in heating and cooling mode |
| EN 14511-4:2022 | Heat pump requirements used with the standard |
| EN 378-1/2/3/4 | Refrigeration and heat pump safety, construction, installation and operation |
| EN 14825:2022 | Seasonal performance-related calculation context |
| EN 60335-1, EN 60335-2-102, EN 60335-2-40, EN 60204-1 | Electrical safety |
| EN 437:2021 | Gas families, test gases, test pressures and appliance categories |
| EN 161:2011+A3:2013 | Automatic shut-off valves |
| EN 549:2019, EN 14800:2007, EN 16436-1:2014+A3:2020 | Gas circuit sealing and hose materials |
| EN IEC 55014-1/2, EN 61000-3-2, EN 61000-3-3, EN 61000-3-11, EN 61000-3-12, EN IEC 61000-6-1, EN 61000-6-3 | EMC emission and immunity requirements |
| EN 12102-1:2017, EN 12102-2:2019 | Sound power level measurement |
| EN 60529:1991 | IP code and waterproof performance |
What does the EN 16905-2:2026 document contain?
EN 16905-2:2026 contains classification rules, design requirements, operating limits, test methods and marking requirements for GEHP appliances. The document includes tables for pressure classes, material properties, wall thicknesses, weld joints, limit temperatures, sound power limits and emission conversion factors, plus formulas for heat input and NO correction.
It also includes detailed test setups for soundness, heat input, temperature rise, overvoltage, waterproofing, power failure, engine startup, CO concentration and NO concentration. Annex C includes a probe arrangement figure for combustion gas sampling, and Annex F gives marking examples for different destination countries and gas settings.
For people who need to test, certify or document a product, the practical value of the standard is that it turns the safety topics into measurable checks, stated limits and required product information.
Relations
- Effective Date
- 18-Jan-2023
- Effective Date
- 16-Sep-2026
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Frequently Asked Questions
EN 16905-2:2026 is a draft published by the European Committee for Standardization (CEN). Its full title is "Gas-fired endothermic engine driven heat pumps - Part 2: Safety". This standard covers: This part of EN 16905 specifies the safety requirements, the safety test conditions and the safety test methods of gas-fired endothermic engine driven heat pumps for heating and/or cooling mode including the engine heat recovery, to be used outdoors. This document specifies minimum operating requirements which ensure that the products are fit for the use designated by the manufacturer when used for space heating and/or cooling. This document is used in conjunction with: a) the terms and conditions, EN 16905-1:2023; b) the test conditions, EN 16905-3:2024; c) the test methods, EN 16905-4:2026; d) the calculation of seasonal performances in heating and cooling mode, EN 16905-5:2022; e) the heat pump, EN 14511-4:2022, EN 378-1:2016+A1:2020, EN 378-2:2016, EN 378 3:2016+A1:2020, EN 378-4:2016+A1:2019 and EN 14825:2022; f) electrical safety, EN 60335-1:2012, EN 60335-2-102:2016, EN 60335-2-40:2003 and EN 60204 1:2018. This document only applies to GEHP appliances with a maximum heat input (based on net calorific value) not exceeding 70 kW at standard rating conditions. This document only applies to GEHP appliances under categories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P and II2Er3P according to EN 437:2021. This document only applies to GEHP appliances: a) that have gas fired endothermic engines under the control of fully automatic control systems; b) that have closed system refrigerant circuits in which the refrigerant does not come into direct contact with the fluid to be cooled or heated; c) where the temperature of the heat transfer fluid of the heating system (heating water circuit) does not exceed 105 °C during normal operation; d) where the maximum operating pressure in the: 1) heating water circuit (if installed) does not exceed 6 bar; 2) domestic hot water circuit (if installed) does not exceed 10 bar. This document is applicable to GEHP appliances only when used for space heating or space cooling or for refrigeration, with or without heat recovery. NOTE This document provides requirements for GEHP appliances with known constructions. For GEHP appliances with any alternative constructions, which are not fully be covered by this standard, the risk associated with this alternative construction needs to be assessed.
This part of EN 16905 specifies the safety requirements, the safety test conditions and the safety test methods of gas-fired endothermic engine driven heat pumps for heating and/or cooling mode including the engine heat recovery, to be used outdoors. This document specifies minimum operating requirements which ensure that the products are fit for the use designated by the manufacturer when used for space heating and/or cooling. This document is used in conjunction with: a) the terms and conditions, EN 16905-1:2023; b) the test conditions, EN 16905-3:2024; c) the test methods, EN 16905-4:2026; d) the calculation of seasonal performances in heating and cooling mode, EN 16905-5:2022; e) the heat pump, EN 14511-4:2022, EN 378-1:2016+A1:2020, EN 378-2:2016, EN 378 3:2016+A1:2020, EN 378-4:2016+A1:2019 and EN 14825:2022; f) electrical safety, EN 60335-1:2012, EN 60335-2-102:2016, EN 60335-2-40:2003 and EN 60204 1:2018. This document only applies to GEHP appliances with a maximum heat input (based on net calorific value) not exceeding 70 kW at standard rating conditions. This document only applies to GEHP appliances under categories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P and II2Er3P according to EN 437:2021. This document only applies to GEHP appliances: a) that have gas fired endothermic engines under the control of fully automatic control systems; b) that have closed system refrigerant circuits in which the refrigerant does not come into direct contact with the fluid to be cooled or heated; c) where the temperature of the heat transfer fluid of the heating system (heating water circuit) does not exceed 105 °C during normal operation; d) where the maximum operating pressure in the: 1) heating water circuit (if installed) does not exceed 6 bar; 2) domestic hot water circuit (if installed) does not exceed 10 bar. This document is applicable to GEHP appliances only when used for space heating or space cooling or for refrigeration, with or without heat recovery. NOTE This document provides requirements for GEHP appliances with known constructions. For GEHP appliances with any alternative constructions, which are not fully be covered by this standard, the risk associated with this alternative construction needs to be assessed.
EN 16905-2:2026 is classified under the following ICS (International Classification for Standards) categories: 27.080 - Heat pumps. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 16905-2:2026 has the following relationships with other standards: It is inter standard links to EN 16905-2:2020, EN 16905-4:2017. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 16905-2:2026 is associated with the following European legislation: EU Directives/Regulations: 2016/2281, 2016/426, 813/2013; Standardization Mandates: M/535, M/560, M/595, M/BC/CEN/89/6. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
EN 16905-2:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 16905-2:2022
01-januar-2022
Toplotna črpalka s plinsko gnanim motorjem z notranjim zgorevanjem - 2. del:
Varnost
Gas-fired endothermic engine driven heat pumps - Part 2: Safety
Gasbefeuerte endothermische Motor-Wärmepumpen - Teil 2: Sicherheit
Pompes à chaleur à moteur endothermique alimenté au gaz - Partie 2: Sécurité
Ta slovenski standard je istoveten z: prEN 16905-2
ICS:
27.080 Toplotne črpalke Heat pumps
oSIST prEN 16905-2:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 16905-2:2022
oSIST prEN 16905-2:2022
DRAFT
EUROPEAN STANDARD
prEN 16905-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 27.080 Will supersede EN 16905-2:2020
English Version
Gas-fired endothermic engine driven heat pumps - Part 2:
Safety
Pompes à chaleur à moteur endothermique alimenté Gasbefeuerte endothermische Motor-Wärmepumpen -
au gaz - Partie 2: Sécurité Teil 2: Sicherheit
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 299.
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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16905-2:2021 E
worldwide for CEN national Members.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 9
4 Classification . 9
4.1 General . 9
4.2 Classification of GEHP appliances . 9
4.3 GEHP appliance classification according to the maximum water side operating
pressure (PMS): . 10
5 Design requirements . 10
5.1 Structure . 10
5.2 Material . 13
5.3 EMC / Electrical requirements . 20
6 Operational requirements . 20
6.1 General requirements . 20
6.2 Soundness . 21
6.3 Heat input at standard rating conditions . 22
6.4 Limit temperatures . 22
6.5 Limit operating conditions . 24
6.6 Insulation resistance . 24
6.7 Transient overvoltage . 24
6.8 Withstand voltage . 24
6.9 Waterproof performance . 24
6.10 Sound power level . 25
6.11 Engine perform . 25
6.12 Power failure . 26
6.13 Abnormalities . 27
6.14 Starting current . 27
7 Test methods . 27
7.1 General test conditions . 27
7.2 Soundness . 29
7.3 Heat input at standard rating conditions . 31
7.4 Limit temperatures . 31
7.5 Limit operating conditions . 32
7.6 Insulation resistance test . 33
7.7 Transient overvoltage test . 33
7.8 Withstand voltage test . 34
7.9 Waterproof performance test . 34
7.10 Sound power level test . 34
7.11 Engine performance . 34
7.12 Power failure test . 35
7.13 Abnormalities test . 35
7.14 Starting current test . 35
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
8 Risk assessment . 35
9 Marking and instructions . 36
9.1 GEHP appliance marking . 36
9.2 Instructions . 38
9.3 Presentation . 40
Annex A (informative) Calculation of conversion of NO . 41
x
A.1 General . 41
Annex B (normative) Engine startup test method . 42
B.1 General . 42
B.2 Test condition . 42
B.3 Test method . 42
Annex C (normative) CO concentration test method . 43
C.1 General . 43
C.2 Test condition . 43
Annex D (normative) NO concentration test method . 46
x
D.1 General . 46
D.2 Engine rpm equivalent method . 46
D.3 Test condition . 46
D.4 Conversion . 47
D.5 Accuracies of measurement . 48
Annex E (normative) Power failure test method. 49
E.1 General . 49
E.2 Test method . 49
Annex F (informative) Examples for marking . 50
F.1 Data-plate (see 9.1.1) . 50
F.2 Additional data-plate (see 9.1.2). 50
Annex G (informative) Examples for NO calculation . 51
x
G.1 E calculation . 51
rpm equivalvent
ppm to mg/kWh conversation . 51
G.2 NOx
G.3 Temperature and humidity correction formula calculation . 51
Annex ZA (informative) Relationship between this European Standard and the
requirements of Commission Regulation (EU) No 2016/426 aimed to be covered . 52
Annex ZB (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) No 813/2013 aimed to be covered . 55
Annex ZC (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) No 2016/2281 aimed to be covered. 56
Bibliography . 57
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
European foreword
This document (prEN 16905-2:2021) has been prepared by Technical Committee CEN/TC 299 “Gas-
fired sorption appliances, indirect fired sorption appliances, gas-fired endothermic engine heat pumps
and domestic gas-fired washing and drying appliances”, the secretariat of which is held by UNI.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 16905-2:2020.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of
EU Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, ZB and ZC, which are
an integral part of this document.
In comparison with the previous edition, the following technical modifications have been made:
— Editorial and technical changes throughout the draft and in Annex ZA, ZB and ZC in order to align
the text to the Ecodesign Requirements stated in Commission Regulation (EU) No 2016/426.
EN 16905 comprises the following parts under the general title, Gas-fired endothermic engine driven
heat pumps:
— Part 1: Terms and definitions;
— Part 2: Safety;
— Part 3: Tests conditions;
— Part 4: Tests methods;
— Part 5: Calculation of seasonal performances in heating and cooling mode.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
Introduction
The GEHP appliances having their condenser cooled by air and by the evaporation of external additional
water are not covered by this European Standard.
Single split and multisplit systems are covered by this European Standard.
The GEHP appliances can have one or more primary or secondary functions.
This European Standard specifies the requirements, test methods and test conditions concerning, in
particular, the construction, safety, fitness for purpose, and rational use of energy, for the rating and
performance calculation of air conditioners and heat pumps using either air, water or brine as heat
transfer media, with gas-fired endothermic engine driven compressors when used for space heating,
cooling and refrigeration, hereafter referred to as "GEHP appliance".
EN 16905-2:2020 has been prepared to address the essential requirements of the European Regulation
(EU) 2016/426 relating to appliances burning gaseous fuels and repealing Directive 2009/142/EC (see
EN 16905-2:2020, Annex ZA).
EN 16905-1:2017, EN 16905-2:2020, EN 16905-3:2017, EN 16905-4:2017 and EN 16905-5:2017 are
linked to the Energy Related Products Directive (2009/125/EC) in terms of tests conditions, tests
methods and seasonal performances calculation methods under Mandate M/535; (see
EN 16905-3:2017, Annex ZA, EN 16905-4:2017, Annex ZA, EN 16905-5:2017, Annex ZA and
EN 16905-2:2020, Annexes ZB and ZC).
These documents will be reviewed whenever new mandates could apply.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
1 Scope
This part of prEN 16905 specifies the safety requirements, the safety test conditions and the safety test
methods of gas-fired endothermic engine driven heat pumps for heating and/or cooling mode including
the engine heat recovery, to be used outdoors.
This document specifies minimum operating requirements which ensure that the products are fit for
the use designated by the manufacturer when used for space heating and/or cooling.
This document is to be used in conjunction with:
a) the terms and conditions, EN 16905-1:2017;
b) the test conditions, EN 16905-3:2017;
c) the test methods, EN 16905-4:2017;
d) the calculation of seasonal performances in heating and cooling mode, EN 16905-5:2017;
e) the heat pump, prEN 14511-4:2021, EN 378-1:2016+A1:2020, EN 378-2:2016,
EN 378-3:2016+A1:2020, EN 378-4:2016+A1:2019 and EN 14825:2018;
f) electrical safety, EN 60335-1:2012, EN 60335-2-102:2016, EN 60335-2-40:2003 and
EN 60204-1:2018.
This document only applies to GEHP appliances with a maximum heat input (based on net calorific
value) not exceeding 70 kW at standard rating conditions.
This document only applies to GEHP appliances under categories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL,
I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P,
II2ELL3B/P, II2L3P, II2H3P, II2E3P and II2Er3P according to EN 437:2021.
This document only applies to GEHP appliances:
a) that have gas fired endothermic engines under the control of fully automatic control systems;
b) that have closed system refrigerant circuits in which the refrigerant does not come into direct
contact with the fluid to be cooled or heated;
c) where the temperature of the heat transfer fluid of the heating system (heating water circuit) does
not exceed 105 °C during normal operation;
d) where the maximum operating pressure in the:
1) heating water circuit (if installed) does not exceed 6 bar;
2) domestic hot water circuit (if installed) does not exceed 10 bar.
This document applies to GEHP appliances only when used for space heating or space cooling or for
refrigeration, with or without heat recovery.
This document is applicable to GEHP appliances that are intended to be type tested. Requirements for
GEHP appliances that are not type tested would need to be subject to further consideration.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (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 161:2011+A3:2013, Automatic shut-off valves for gas burners and gas appliances
EN 378-2:2016, Refrigerating systems and heat pumps - Safety and environmental requirements - Part 2:
Design, construction, testing, marking and documentation
EN 437:2021, Test gases - Test pressures - Appliance categories
EN 549:2019, Rubber materials for seals and diaphragms for gas appliances and gas equipment
CR 1404:1994, Determination of emissions from appliances burning gaseous fuels during type-testing
EN 1561:2011, Founding - Grey cast irons
EN 10029:2010, Hot-rolled steel plates 3 mm thick or above - Tolerances on dimensions and shape
EN 10226-1:2004, Pipe threads where pressure tight joints are made on the threads - Part 1: Taper
external threads and parallel internal threads - Dimensions, tolerances and designation
EN 10226-2:2005, Pipe threads where pressure tight joints are made on the threads - Part 2: Taper
external threads and taper internal threads - Dimensions, tolerances and designation
EN 12102-1:2017, Air conditioners, liquid chilling packages, heat pumps, process chillers and
dehumidifiers with electrically driven compressors - Determination of the sound power level - Part 1: Air
conditioners, liquid chilling packages, heat pumps for space heating and cooling, dehumidifiers and
process chillers
EN 12102-2:2019, Air conditioners, liquid chilling packages, heat pumps, process chillers and
dehumidifiers with electrically driven compressors - Determination of the sound power level - Part 2: Heat
pump water heaters
EN 14800:2007, Corrugated safety metal hose assemblies for the connection of domestic appliances using
gaseous fuels
EN 16436-1:2014+A3:2020, Rubber and plastics hoses, tubing and assemblies for use with propane and
butane and their mixtures in the vapour phase - Part 1: Hoses and tubings
EN 16905-1:2017, Gas-fired endothermic engine driven heat pumps - Part 1: Terms and definitions
EN 16905-3:2017, Gas-fired endothermic engine driven heat pumps - Part 3: Test conditions
EN 16905-4:2017, Gas-fired endothermic engine driven heat pumps - Part 4: Test methods
EN 16905-5:2017, Gas-fired endothermic engine driven heat pumps - Part 5: Calculation of seasonal
performances in heating and cooling mode
EN IEC 55014-1:2021, Electromagnetic compatibility - Requirements for household appliances, electric
tools and similar apparatus - Part 1: Emission
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
EN IEC 55014-2:2021, Electromagnetic compatibility - Requirements for household appliances, electric
tools and similar apparatus - Part 2: Immunity - Product family standard
EN 60335-1:2012 , Household and similar electrical appliances – Safety – Part 1: General requirements
EN 60335-2-40:2003 , Household and similar electrical appliances - Safety - Part 2-40: Particular
requirements for electrical heat pumps, air-conditioners and dehumidifiers
EN 60335-2-102:2016, Household and similar electrical appliances - Safety - Part 2-102: Particular
requirements for gas, oil and solid-fuel burning appliances having electrical connections
EN 60529:1991 , Degrees of protection provided by enclosures (IP Code)
EN 61000-3-2:2014, Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for harmonic current
emissions (equipment input current ≤ 16 A per phase)
EN 61000-3-3:2013, Electromagnetic compatibility (EMC) - Part 3-3: Limits - Limitation of voltage
changes, voltage fluctuations and flicker in public low-voltage supply systems, for equipment with rated
current <= 16 A per phase and not subject to conditional connection
EN IEC 61000-3-11:2019, Electromagnetic compatibility (EMC) - Part 3-11: Limits - Limitation of voltage
changes, voltage fluctuations and flicker in public low-voltage supply systems - Equipment with rated
current ≤ 75 A and subject to conditional connection
EN 61000-3-12:2011, Electromagnetic compatibility (EMC) - Part 3-12: Limits - Limits for harmonic
currents produced by equipment connected to public low-voltage systems with input current > 16 A and <=
75 A per phase
EN IEC 61000-6-1:2019, Electromagnetic compatibility (EMC) - Part 6-1: Generic standards - Immunity
standard for residential, commercial and light-industrial environments
EN 61000-6-3:2007, Electromagnetic compatibility (EMC) - Part 6-3: Generic standards - Emission
standard for residential, commercial and light-industrial environments
EN ISO 2553:2019, Welding and allied processes - Symbolic representation on drawings - Welded joints
(ISO 2553:2019, Corrected version 2021-09)
EN ISO 3166-1:2020, Codes for the representation of names of countries and their subdivisions - Part 1:
Country code (ISO 3166-1:2020)
EN ISO 4063:2010, Welding and allied processes - Nomenclature of processes and reference numbers (ISO
4063:2009, Corrected version 2010-03-01)
As impacted by EN 60335-1:2012/A11:2014, EN 60335-1:2012/AC:2014, EN 60335-1:2012/A13:2017,
EN 60335-1:2012/A1:2019, EN 60335-1:2012/A2:2019, EN 60335-1:2012/A14:2019 and
EN 60335-1:2012/A15:2021.
As impacted by EN 60335-2-40:2003/A11:2004, EN 60335-2-40:2003/A12:2005,
EN 60335-2-40:2003/A1:2006, EN 60335-2-40:2003/Cor.:2006, EN 60335-2-40:2003/A2:2009,
EN 60335-2-40:2003/Cor.:2010, EN 60335-2-40:2003/A13:2012 and EN 60335-2-40:2003/A13:2012/AC:2013.
As impacted by EN 60529:1991/A1:2000 and EN 60529:1991/A2:2013.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
EN ISO 7010:2020, Graphical symbols - Safety colours and safety signs - Registered safety signs (ISO
7010:2019, Corrected version 2020-06)
ISO 857-2:2005, Welding and allied processes - Vocabulary - Part 2: Soldering and brazing processes and
related terms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 16905-1:2017 and the
following 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
maximun water operating pressure
PMS
maximum water operating pressure at which the GEHP appliance can be used, in bars given by the
symbol “PMS”, followed by the equals sign, the numerical value and the unit “bar
3.2
Ignition Safety Time
TSA
time elapsing between the start and the stop of the gas supply to internal combustion engine in the
event of ignition not taking place
3.3
Maximum Ignition Safety Time
TSA max
ignition safety time measured under the least favourable conditions of ambient temperature and
variation in supply voltage
4 Classification
4.1 General
GEHP appliances can be classified according to:
— the gases they use;
— the unit structure;
— air blowing system.
4.2 Classification of GEHP appliances
4.2.1 Classification of gases
Gases are classified into three families, possibly divided into groups according to the value of the Wobbe
index. Families and groups of gas used in this standard are in accordance with those of the
nd rd
EN 437:2021. This standard is for GEHP appliances working with 2 and 3 gas family only.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
4.2.2 Classification according to the unit structure
4.2.2.1 Single split
Single GEHP appliance in combination with single heating/cooling device to form a discrete matched
functional unit.
4.2.2.2 Multi split
Single GEHP appliance with a single refrigerant circuit in combination with multiple heating/cooling
devices.
4.2.3 Classification according to the air blowing system
4.2.3.1 Non ducted type
Air introduced from the space containing the unit and discharged within the same space.
4.2.3.2 Ducted type
Air introduced from the space containing the unit and discharged outside this space.
4.3 GEHP appliance classification according to the maximum water side operating
pressure (PMS):
— pressure class 1: PMS = 1 bar
— pressure class 2: PMS = 3 bar
— pressure class 3: 3 bar < PMS ≤ 6 bar
NOTE Internal cooling circuits in GEHP appliances are not considered under this classification, e.g. internal
cooling circuits for internal combustion engine in GEHP appliances.
5 Design requirements
5.1 Structure
5.1.1 General
The structure of the equipment shall satisfy the following requirements in consideration of safety and
durability:
a) The edge of the part which people touch with hands in service or in the case of maintenance and
checking shall be sufficiently smooth.
b) The control section and electric section shall not be influenced by the weather condition.
c) The thermal insulation material, etc. shall not produce detachment or omission in normal use.
d) The movable parts of the blower, etc. shall not easily come into contact with a human body in
normal use.
e) The thermal insulation material, etc. used near (less than 50 mm) the electric component section
shall be fire-resistant, except in cases where there is no possibility that danger such as electric
shock, fire arises if the thermal insulation material, etc. burns.
f) The confirmation of drain of the condensed water can be easily performed.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
g) The connecting port, etc. for refrigerant collection shall be provided.
h) The refrigerant circuit shall be safe for an abnormal pressure rise.
i) The GEHP appliance shall be equipped with control and safety devices for start, operation and
control of the gas supply.
j) These devices shall ensure the automatic start and the automatic monitoring for the operating
functions of the engine and the GEHP appliance as well as the gas supply.
k) In case of failure of the normal operating functions (malfunctions), the gas supply shall be cut off, if
need be, with lock-out in accordance with the operating programme.
l) The functional safety specification for control and supervision as well as for the automatic restart
shall be part of the design documents.
m) The design of the control and safety system shall be such that it is not possible to perform two or
more actions which are unacceptable in combination. The order of the actions shall be fixed in such
a manner that it is not possible to change it.
n) Any parts of a GEHP appliance which are not intended to be altered by the user or the installer shall
be protected in an appropriate manner. Paint may be used for this purpose provided that it
withstands the temperature to which it is subjected during normal operation of the GEHP
appliance.
o) GEHP appliances shall be so designed and constructed that gas release at any state of operation is
limited in order to avoid a dangerous accumulation of unburned gas in the GEHP appliance.
5.1.2 Structure of each part
5.1.2.1 Gas inlet connection
The gas inlet connection shall be as follows:
a) The gas inlet connection portshall be exposed to the outside or shall be located so that it is able to
be easily identified visually.
b) For the screw threads of the gas connecting port, those specified in EN 10226-1:2004 or
EN 10226-2:2005 shall be used.
5.1.2.2 Automatic shut-off valve
The automatic shut-off valve shall be as follows.
a) The gas passage to an engine shall be closed by two or more automatic shut-off valves provided in
series at the time of engine stop.
b) Each automatic shut-off valve shall have the independent function.
c) Each automatic shut-off valve shall comply with the requirement of EN 161:2011+A3:2013.
d) Composition of the automatic shut-off valves shall be, at least, C+C or B+J.
e) For non-volatile lockout two or more valves shall be closed simultaneously.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
In response to a control device, if the delay between the signals to close the two valves is not greater
than 1 s, the signals are considered to be simultaneous.
5.1.2.3 Gas carrying circuit
The gas carrying circuit shall be as follows:
a) The gas carrying circuit used for the part which becomes negative pressure shall have sufficient
strength to negative pressure. Under the normal operation condition, each part of the gas carrying
circuit shall be free from abnormalities such as deformation during the period from the close of the
gas shut off valve in the gas inlet side to the stop of the engine.
b) The surface treatment such as a tinning shall be given to the inner surface of the copper pipe of 2
mm or less in inner diameter used for a gas carrying circuit.
c) The gas carrying circuit used for the part which becomes positive pressure shall have sufficient
strength to positive pressure.
d) When there is leakage of fuel gas from the gas carrying circuit used for the part which becomes
positive pressure, the GEHP appliance shall be structured so that the leaked fuel gas shall comply
with the requirements of the soundness gas carrying circuit specified in 6.2.1.
e) Gas carrying circuit shall be sound so that at any state of operation unburned gas in the GEHP
appliance does not accumulate.
5.1.2.4 Soundness of the engine
Soundness of the engine shall be ensured according to the following items:
The leakage of the engine shall
a) be ignited immediately with the mixture designed to be burned in the engine, or
b) be contained by the entire engine being surrounded by combustion air or cooling water, or
c) be released easily outside into atmosphere, or
d) lead to non-operation of the engine under such leakage conditions.
5.1.2.5 Combustion products circuit
The combustion products circuit shall be as follows:
a) The combustion products circuit shall have the structure to endure the temperature of combustion
products and vibration of an engine;
b) The ducts, bends, if any, and the terminal or fitting piece shall fit together correctly and shall form a
stable assembly. Parts intended to be dismantled for periodic servicing shall be designed and
arranged so that soundness is assured after reassembly. Any fitting piece shall allow a sound
connection to be made to the system intended for the evacuation of combustion products and
supply of air;
c) The opening of combustion products exhaust outlet shall be structured so that a steel ball of 16 mm
in diameter by applying a force of 5 N in every possible position cannot enter or birds, etc. cannot
invade;
d) Condensation shall not affect the operational safety, then the combustion products circuit shall
have the structure which is capable of discharging condensation drain without blocking the
combustion products;
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
e) All parts of the heat exchanger(s) and other parts of the GEHP appliance likely to come into contact
with condensate shall be constructed of corrosion resistant materials or materials protected by a
suitable coating and maintained in accordance with the manufacturer's instructions;
f) If the technical documentation states the chemical composition of the condensate, the composition
shall be verified at the end of the test under rating conditions in cooling mode according to
EN 16905-3:2017, 4.2.
5.1.2.6 Casing
The casing shall be as follows:
a) The opening of casing to intake air for combustion shall be structured so that a steel ball of 16 mm
in diameter when applied with a force of 5 N cannot enter.
b) The panel for checking and maintenance shall have the structure to endure the intended use of
attachment and detachment.
5.1.2.7 Motor for engine startup
The motor for engine startup shall have protection device (for example, fuse) to prevent overheat.
5.1.2.8 Engine ignition device
The engine ignition device shall be structured so that the noise radiation (radio noise) generated by the
engine ignition device gives no interference to other equipment.
5.1.2.9 Engine protective device
The engine protective device shall be as follows:
a) When the number of rotations of an engine exceeds that designated by the design documentation,
the engine protective device shall have the function in which the engine stops and the gas carrying
circuit is automatically closed.
b) When the engine oil decreases to the degree indicated in the design documentation, the engine
protective device shall have the function in which the engine stops and the gas carrying circuit is
automatically closed.
c) When the engine cooling water (anti-freeze solution) exceeds the temperature indicated in the
design documentation, the engine protective device shall have the function in which the engine
stops and the gas carrying circuit is automatically closed.
5.1.3 Refrigerant circuit
The strength of each part of refrigerant circuit shall conform to the specification of EN 378-2:2016 and
have the structure to endure vibration of an engine, etc. sufficiently.
5.1.4 Engine lubricant oil circuit
In case of leakage from the lubricant oil circuit, there shall be no escape of oil to outside of GEHP
appliance.
5.2 Material
5.2.1 Domestic hot water circuit
The materials of the parts containing domestic water shall not affect the quality of the domestic water
in respect of either health or taste.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
The whole of the domestic hot water circuit shall be made up of corrosion resistant materials or shall be
protected against corrosion.
5.2.2 Gas carrying circuit
The material used for the part which contains fuel gas shall be as follows:
a) Either metallic material or other materials fulfilling the following requirements:
1) anti-corrosion or of which the surface is given an anti-corrosion treatment,
2) quality to sufficiently endure the pressure and components of a fuel gas and shall be conform to
the specification of EN 16436-1:2014+A3:2020 → (for rubber).
b) The metal braided flexible hose shall be that which conforms to EN 14800:2007.
c) The material of the gas carrying circuit of the part in which the gas pressure downstream from the
regulator becomes negative pressure shall sufficiently endure the negative pressure.
d) Rubber materials of packing and sealing used in gas carring circuit shall comply with the relevant
requirements of Class A2 as defined in EN 549:2019.
5.2.3 Combustion products circuit
The material used for the combustion products circuit shall be as follows.
a) The metallic material shall be heatproof and anti-corrosion or of which the surface is given an anti-
corrosion treatment.
b) The material other than metal shall be resistant to combustion gas and drain water.
5.2.4 Thermal insulation material, etc.
The thermal insulation material, sound absorbing material, etc. of the periphery of an engine shall be
that which does not burn or naturally burns out within 10 s when it burns.
5.2.5 Materials and thicknesses of walls or tubes under water pressure of pressure class 3
5.2.5.1 General
The characteristics of the materials and the thicknesses of walls under pressure shall comply with the
requirements of 5.2.5.2, 5.2.5.3 and 5.2.5.4. If other materials and/or other thicknesses are used, these
shall have an equivalent level of fitness for purpose.
5.2.5.2 Materials
Materials for parts under pressure shall be appropriate for their duty and envisaged use.
The following materials satisfy these criteria:
— steels that have the properties and chemical composition detailed in Table 1;
— cast irons that have the mechanical properties detailed in Table 2;
— the non-ferrous materials detailed in Table 3 and Table 4.
5.2.5.3 Thickness
The minimum wall thicknesses of parts under water pressure are given in Table 5 and Table 6.
For rolled steel the tolerances are given in EN 10029:2010.
oSIST prEN 16905-2:2022
prEN 16905-2:2021 (E)
The thicknesses of cast walls given in the production drawings shall not be less than the nominal
minimum thicknesses given in Table 6 for parts of cast iron or of cast materials which are subjected to
pressure. The actual minimum thickness of the GEHP appliance sections and of parts subjected to
pressure shall be greater than 0,8 times those given in the drawings.
5.2.5.4 Welded seams and welding fillers
Materials shall be suitable for welding. Examples of materials are given in Table 1 and do not require
additional heat treatment for welding.
Welded seams shall show no cracks or bonding faults and butt welded seams shall be faultlessly welded
over the whole cross-section.
Single-sided fillet welds and half Y-welds without full penetration into the base metal shall not be
subjected to bending stresses. Double fillet welds are permissible if sufficiently cooled.
Corner welds, edge welds and similar welds which are subject to considerable bending stresses are to
be avoided.
For welded-in longitudinal stays, stay tubes or stay bolts, the shearing cross-section of the fillet weld
shall be at least 1,25 times the required cross-section of the bolt or stay tube.
Details of the welds mentioned are given in Table 7. Welding fillers shall permit a joint appropriate to
the base material to be made.
The terms given in Table 7 are in accordance with EN ISO 2553:2019; the reference numbers of welding
processes are respectively in accordance with ISO/TR 25901-3, ISO 857-2:2005 and EN ISO 4063:2010.
Table 1 — Mechanical properties and chemical compositions of carbon and stainless steels
Mechanical properties Chemical composition by
%
Materials Steel Tensile Yield Breaking Breaking C P S Si Mn Cr Mo Ni Ti Nb/Ta
type strength point elongation elongation
Rm RoH/Rp Along at Lo Atransv at
0,2 = 5 do Lo = 5 do
2 2
N/mm N/mm % %
carbon ≤ 520 a ≥ 20 — ≤ ≤0,05 ≤0,05 — — — — — — —
≤ 0,7
0,25
Pipes,
sheets ferritic ≤ 600 ≥ 250 ≥ 20 ≥ 15 ≤ ≤0,045 ≤0,030 ≤ 1,0 ≤1,0 15,5 ≤1,5 — ≤ 7 ≤ 12 ×
0,08 to × %C
18 %C
austenitic ≤ 800 ≥ 180 ≥ 30 ≥ 30 ≤ ≤0,045 ≤0,030 ≤ 1,0 ≤2,0 16,5 2,0 9 ≤ 5 ≤ 8 × %C
0,08 to to to ×
20 3,0 15 %C
a
Ratio yield point–tensile strength.
An adequate high temperature yield point for the highest possible temperature of the steel shall be guaranteed.
oSIST prEN 16905-2:2022
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Table 2 — Minimum requirements for cast iron
Flake graphite cast iron (EN 1561:2011):
– Tensile strength R ≥ 150 N/mm
m
– Brinell hardness 160 HB to 220 HB 2,5/187,5
Spheroidal graphite cast iron (annealed ferritic):
– Tensile strength R ≥ 400 N/mm
m
– Notch impact strength ≥ 23 J/cm
Table 3 — Parts in aluminium and aluminium alloys
Tensile strength Temperature
range
R
m
N/mm °C
Al 99,5 ≥ 75 up to 300
Al Mg2 Mn 0,8 ≥ 275 up to 250
Table 4 Parts in copper or copper alloys
Tensile strength Temperature
R
range
m
N/mm °C
SF – Cu ≥ 200 up to 250
Cu Ni 30 Fe ≥ 310 up to 350
Table 5 — Minimum thicknesses for rolled parts
Carbon steels; aluminium Protected steel
...