kSIST FprEN 1490:2026

• Abstract:

  This document specifies dimensions, materials and performance requirements, including test methods, for combined temperature and pressure relief valves, of nominal sizes from DN 15 to DN 40, having working pressures from 0,3 MPa (3 bar) to 1,0 MPa (10 bar).; Combined temperature and pressure relief valves control and limit the temperature and pressure of the water contained in a hot water heater to the valves rating pressure and a temperature not exceeding 100 °C and will prevent water to steam formation when other temperature controls fail.; Combined temperature and pressure relief valves are classified having a maximum opening temperature range from 90 °C to 95 °C for class A and 75 °C to 80 °C for class B.; They are not intended to act as an expansion valve and do not control cold water flow.; Alone it does not constitute the control functions for a water heater.; A combined temperature and pressure relief valve is an independently mechanically operating device, therefore operating without an external energy source.; NOTE The use of the device specified in this document does not override the need to use controls (e.g. thermostats and cut-outs) which act directly on the power sources of water heaters (for more information, see Annex B).

• Status: Not Published
• Public Enquiry End Date: 30-Dec-2025
• ICS: 91.140.60 - Water supply systems
• Technical Committee: IOVO - Water supply and waste water engineering
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 06-Aug-2026
• Due Date: 24-Sep-2026
• Completion Date: 07-Aug-2026
• Directive: Harmonized Standard305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Ref Project: FprEN 1490 - Building valves - Combined temperature and pressure relief valves - Tests and requirements

• Referred By: SIST EN ISO 15614-11:2026 - Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 11: Electron and laser beam welding (ISO 15614-11:2025)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 15614-5:2024 - Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 5: Arc welding of titanium, zirconium and their alloys (ISO 15614-5:2024)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 15614-9:2026 - Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 9: Underwater hyperbaric wet welding (ISO 15614-9:2025)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 15614-13:2024 - Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 13: Upset (resistance butt) and flash welding (ISO 15614-13:2023)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 15614-2:2025 - Specification and qualification of welding procedures for metallic materials - Welding procedure test - Part 2: Arc welding of aluminium and its alloys (ISO 15614-2:2025)
• Effective Date: 28-Jan-2026
• Revises: SIST EN 1490:2000 - Building valves - Combined temperature and pressure relief valves - Tests and requirements
• Effective Date: 18-Dec-2024

Overview

kSIST FprEN 1490:2026 is an international standard that defines the requirements and test methods for combined temperature and pressure relief valves, specifically designed for building water supply systems. Developed by SIST and the CEN/TC 164 technical committee, this standard covers valves with nominal sizes from DN 15 to DN 40 and working pressures ranging from 0.3 MPa (3 bar) to 1.0 MPa (10 bar). These valves are critical safety devices that protect hot water heaters by preventing excessive temperature and pressure, ensuring both system safety and compliance with building codes across Europe.

Key Topics

• Scope of Application
  This standard applies to mechanical combined temperature and pressure relief valves, which do not require an external energy source and are intended for use in potable hot water systems within buildings.

• Temperature and Pressure Ratings
  The valves are designed to operate within specific temperature and pressure ranges.

  • Class A: Maximum opening temperature between 90 °C and 95 °C
  • Class B: Maximum opening temperature between 75 °C and 80 °C
  • Maximum working temperature: 100 °C

• Functional Requirements

  • Performance: The valves must reliably control and limit the temperature and pressure within specified tolerances.
  • Safety: Devices prevent water-to-steam conversion if primary controls fail.
  • Independence: These are mechanically operated devices, functioning without external power.

• Testing and Verification

  • Hydraulic and temperature tests: Validate opening/closing actions, water tightness, and discharge capacity.
  • Endurance and mechanical strength tests: Ensure durability.
  • Coating and material tests: Confirm resistance to corrosion and compatibility with potable water.
  • Disinfection compatibility: Assess continued function after exposure to common disinfectants.

• Dimensional and Marking Requirements

  • Clear definition of connection types and marking for identification.
  • Compatibility with relevant European standards for pipe threads and fittings.

Applications

The combined temperature and pressure relief valves covered by kSIST FprEN 1490:2026 are essential for:

• Residential and Commercial Hot Water Heaters
  Ensuring the safe operation of water heaters by automatically discharging excess pressure or temperature.

• Boiler Safety Systems
  Used as a backup safeguard against overheating or over-pressurization.

• Water Supply Systems in Buildings
  Vital in any installation where water is heated and stored under pressure, such as apartment complexes, hotels, hospitals, and public buildings.

• Regulatory Compliance
  Helps manufacturers and building professionals comply with European regulations regarding the safety of water supply installations, contributing to risk mitigation and promoting public health.

Note: These valves do not substitute for thermostats, cut-outs, or controls that directly interrupt power supplies to water heaters.

Related Standards

Implementing kSIST FprEN 1490:2026 involves reference to several related European and international standards, including:

• EN 806 (all parts): Specifications for installations inside buildings conveying water for human consumption
• EN 1717: Protection against pollution of potable water in installations and general requirements for backflow prevention
• EN 1254-2: Copper and copper alloys - Plumbing fittings - Compression fittings
• EN 10226-1 & EN ISO 228-1: Pipe threads for pressure-tight and non-pressure-tight joints
• EN ISO 6509 (all parts): Determination of dezincification resistance of copper alloys

By ensuring compatibility with these standards, building professionals can guarantee system integrity, safety, and the longevity of water supply installations.

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Keywords: combined temperature and pressure relief valves, building valves standard, hot water safety, valve test requirements, potable water systems, safety device, kSIST FprEN 1490:2026, SIST, CEN standards, EN 1490, water heater safety, European plumbing standards.

SLOVENSKI STANDARD
oSIST prEN 1490:2025
01-december-2025
Ventili v stavbah - Kombinirani temperaturno tlačni razbremenilni ventili - Preskusi
in zahteve
Building valves - Combined temperature and pressure relief valves - Tests and
requirements
Gebäudearmaturen - Kombinierte Druck-Temperaturventile - Prüfungen und
Anforderungen
Robinetterie de bâtiment - Soupapes combinées température et pression - Essais et
prescriptions
Ta slovenski standard je istoveten z: prEN 1490
ICS:
91.140.60 Sistemi za oskrbo z vodo Water supply systems
oSIST prEN 1490:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 1490:2025
oSIST prEN 1490:2025
DRAFT
EUROPEAN STANDARD
prEN 1490
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 91.140.60 Will supersede EN 1490:2000
English Version
Building valves - Combined temperature and pressure
relief valves - Tests and requirements
Robinetterie de bâtiment - Soupapes combinées Gebäudearmaturen - Kombinierte Druck-
température et pression - Essais et prescriptions Temperaturventile - Prüfungen und Anforderungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 164.
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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1490:2025 E
worldwide for CEN national Members.

oSIST prEN 1490:2025
prEN 1490:2025 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Materials and surface finishes . 9
4.1 General. 9
4.2 Materials . 10
4.3 Detection of residual stress . 10
4.3.1 General. 10
4.3.2 Test . 10
4.3.3 Test method (Procedure) . 10
4.3.4 Requirements . 11
4.4 Coating adherence test. 11
4.4.1 General. 11
4.4.2 Test method . 11
4.4.3 Requirements . 12
5 Compatibility of the valve with disinfection . 12
5.1 General. 12
5.2 Requirement . 12
5.3 Test method . 12
6 Design and dimensional requirements. 12
6.1 General guidance . 12
6.2 Pressures . 13
6.2.1 Nominal set pressure (P ) . 13
nr
6.2.2 Water tightness pressure (P ) . 13
e
6.2.3 Initial opening pressure (P ) . 13
dc
6.2.4 Opening pressure (P ) . 13
o
6.2.5 Rating pressure (P ) . 13
dn
6.2.6 Closing pressure (P ) . 13
f
6.3 Dimensional characteristics . 13
6.3.1 nominal outlet diameter . 13
6.3.2 end connections . 13
6.3.3 Exclusions . 13
6.3.4 Easing gear (manual control device) . 13
7 Tolerances of parameters and accuracy of measure instruments . 14
7.1 Tolerances on set parameters . 14
7.2 Accuracy of measuring instruments . 14
7.3 Test media . 14
8 Hydraulic and temperature tests and requirements . 14
8.1 Opening and reseating temperature test . 14
8.1.1 General. 14
8.1.2 Preparation . 15
oSIST prEN 1490:2025
prEN 1490:2025 (E)
8.1.3 Verification that the device is closed . 15
8.1.4 Opening temperature (t ) . 16
o
8.1.5 Closing temperature (t ) . 16
f
8.2 Water tightness test, opening and reseating pressure test, and pressure of nominal
flow test . 16
8.2.1 Water tightness pressure (P ) . 16
e
8.2.2 Nominal opening pressure (P ) . 17
o
8.2.3 Rating pressure (P ) . 17
dn
8.2.4 Closing pressure (Pf) . 17
8.3 Water discharge test . 18
8.3.1 Procedure . 18
8.3.2 Requirement . 18
8.4 Endurance test . 18
8.4.1 Test 1 (pressure) . 18
8.4.2 Requirement . 19
8.4.3 Test 2 (temperature) . 19
8.4.4 Requirement . 19
9 Mechanical tests and requirements . 19
9.1 Mechanical strength . 19
9.1.1 Back pressure test . 19
9.1.2 Body strength test . 19
9.1.3 Bending moment test of the body of the device . 19
9.2 Mechanical strength test of the easing gear (manual control device) . 20
9.2.1 Procedure . 20
9.2.2 Requirement . 20
9.3 Operation of the easing gear. 20
9.3.1 Procedure . 20
9.3.2 Requirement . 20
9.4 Easing gear endurance test . 20
9.4.1 Procedure . 20
9.4.2 Requirement . 20
10 Acoustic tests and requirements . 20
11 Classification . 21
12 Designation . 21
13 Nominal size . 21
14 Marking . 21
15 Technical documents and presentation at delivery . 22
Annex A (informative) Dimensional proposals . 23
Annex B (informative) Classification of water heaters according to heating method . 26
Annex C (informative) Test rig: Chapter 5: Disinfection // Guidance Document WG 14 . 28
Annex D (informative) Calculation method for the nominal power rating . 29
Bibliography . 30

oSIST prEN 1490:2025
prEN 1490:2025 (E)
European foreword
This document (prEN 1490:2025) has been prepared by Technical Committee CEN/TC 164 “Water
supply”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1490:2000.
This document includes the following significant technical changes with respect to EN 1490:2000:
— the clause on materials was completely revised;
— class A and class B for the temperature range were introduced;
— steam test was deleted;
— dimensional requirements were moved to an informative annex;
— testing with disinfectant was introduced;
— torque test was added;
— testing of the pressure relief valve was changed and optimized;
— coating test procedure was revised;
— normative references were updated;
— editorial changes have been made throughout the entire document.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
Introduction
With regard to the potential adverse effect on the quality of water intended for human consumption,
caused by the product covered by this document:
a) This document provides no information as to whether the product may be used without restriction
in any of the Member States of the EU or EFTA.
b) It should be noted that, whilst awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and or the characteristics of this product remain in force.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
1 Scope
This document specifies dimensions, materials and performance requirements, including test methods,
for combined temperature and pressure relief valves, of nominal sizes from DN 15 to DN 40, having
working pressures ) from 0,3 MPa (3 bar) to 1,0 MPa (10 bar).
Combined temperature and pressure relief valves control and limit the temperature and pressure of the
water contained in a hot water heater to the valves rating pressure and a temperature not exceeding
100 °C and will prevent water to steam formation when other temperature controls fail.
Combined temperature and pressure relief valves are classified having a maximum opening temperature
range from 90 °C to 95 °C for class A and 75 °C to 80 °C for class B.
They are not intended to act as an expansion valve and do not control cold water flow.
Alone it does not constitute the control functions for a water heater.
A combined temperature and pressure relief valve is an independently mechanically operating device,
therefore operating without an external energy source.
NOTE The use of the device specified in this document does not override the need to use controls (e.g.
thermostats and cut-outs) which act directly on the power sources of water heaters (for more information, see
Annex B).
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 806 (all parts), Specifications for installations inside buildings conveying water for human consumption
EN 1254-2, Copper and copper alloys — Plumbing fittings — Part 2: Compression fittings for use with
copper tubes
EN 1717, Protection against pollution of water intended for human consumption in potable water
installations and general requirements for devices to prevent pollution by backflow
EN 10226-1, 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 ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions,
tolerances and designation (ISO 228-1)
EN ISO 6509 (all parts), Corrosion of metals and alloys — Determination of dezincification resistance of
copper alloys with zinc (ISO 6509 (all parts))

All pressures are gauge unless otherwise stated.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
temperature relief valve
temperature activated valve which opens automatically at a specified set temperature to discharge fluid
Note 1 to entry: It is fitted to water heaters to prevent the temperature of the contained water from exceeding
100 °C.
3.2
pressure relief valve
pressure activated valve which opens automatically at a specified set pressure to discharge fluid
Note 1 to entry: It is fitted to prevent the pressure in a water heater from exceeding the nominal set pressure.
3.3
combined temperature and pressure relief valve
valve which is capable of performing the function of both a temperature relief valve and a pressure relief
valve
Note 1 to entry: For the purposes of this document, the combined temperature and pressure relief valve is hereafter
referred to as ‘the device’.
3.4
thermal element
thermal probe and associated control rods that provide the thermal control
3.5
air break to drain
vertical distance realized by air inlets or full disconnection between the lowest point of the outlet and the
spill over level of the atmospheric drain overflow
3.6
nominal set pressure
P
nr
pressure of the device which is set on production
Note 1 to entry: The “nominal set pressure” (Pnr) is often called “set pressure”.
Note 2 to entry: See Figure 1.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
Key
X time
Y pressure
Figure 1 — Pressures
3.7
water tightness pressure
P
e
pressure up to which the device is closed
Note 1 to entry: See Figure 1.
3.8
initial opening pressure
P
dc
pressure at which the device opens for the first time, as indicated by the first droplet of water at the outlet
of the device, after a period of storage
Note 1 to entry: See Figure 1.
3.9
opening pressure
P
o
pressure at which the device opens as indicated by the appearance of water at the outlet of the device
Note 1 to entry: See Figure 1.
3.10
rating pressure
P
dn
pressure at which the discharged flow is above the limit given in Table 2
Note 1 to entry: See Figure 1 and Table 2.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
3.11
closing pressure
P
f
pressure at which the device closes after having reached the rating pressure
Note 1 to entry: See Figure 1.
3.12
maximum working temperature
tmax
maximum temperature at which the device is designed to be used (100 °C)
3.13
nominal set temperature class A
nominal set temperature class B
t
nr
temperature range at which the device is set on production
Note 1 to entry: For class A, the range is 90 °C to 95 °C. For class B, the range is 75 °C to 80 °C.
3.14
initial opening temperature
t
dc
temperature at which the device opens, as indicated by the first droplet of water, after a period of storage
3.15
opening temperature
t
o
temperature at which the device opens, as indicated by the appearance of water at the outlet of the device
3.16
closing temperature
t
f
temperature at which the device closes after discharging under temperature conditions
3.17
water discharge capacity
rate of water discharge, l/h, that can be discharged through the device under the conditions specified in
the test in 8.2
3.18
nominal power rating
power rating, in Table 5, to be assigned to a device
4 Materials and surface finishes
4.1 General
The selection of materials is the responsibility of the manufacturer, provided they satisfy the following
requirements:
a) materials and coatings shall not contaminate the potable water;
b) the nature of the materials and coatings used shall be stated in a technical document;
oSIST prEN 1490:2025
prEN 1490:2025 (E)
c) materials with insufficient corrosion resistance (e.g. cast iron, aluminium) shall have additional
protection;
d) the materials used shall be suitable for the temperatures specified in the tests in this document;
e) the materials, and in particular copper alloys, for which recommendations or
European/International standards exist, shall comply with the relevant recommendations or
European/International standards.
4.2 Materials
All materials coming into contact with water intended for human consumption shall present no health
risk nor cause any change to the water in terms of quality, appearance, smell or taste.
NOTE It is pointed out that whilst awaiting the adoption of verifiable European criteria for testing materials in
contact with water intended for human consumption, existing national regulations concerning the use and/or the
characteristics of these products remain in force.
Copper-zinc alloys containing more than 15 % zinc are subject to dezincification when submitted to
water capable of dezincification. In the countries where the use of products made of dezincification
resistant materials is required, the materials used shall guarantee a dezincification depth less than
200 μm in any direction. For this purpose, materials shall be tested in accordance with
EN ISO 6509 (all parts) and the product shall be marked in compliance with the indications according to
Clause 14.
4.3 Detection of residual stress
4.3.1 General
This test shall be performed for bodies made out of brass materials and with female threads according to
EN 10226-1 and compression ends according to EN 1254-2.
4.3.2 Test
This test is based on ISO 6957. Its purpose is to verify the resistance to cracking under stress corrosion
in ammonia medium (as described in 4.3.3 b).
The test entails exposing test specimens consisting of the assembled device in an atmosphere loaded with
ammonia vapour.
4.3.3 Test method (Procedure)
The paragraph below details ISO 6957.
Test solution:
a) Use solutions of analysis quality and of distilled water.
b) Solution of ammonia at 20 % (in weight).
c) The pH of the test solution shall be adjusted to 9,5 by using hydrochloric acid.
d) The test temperature shall be (23 ± 2) °C with a measurement uncertainty of ±1 K.
Test specimen:
e) The test specimen consists of three samples of a single assembled product. The test specimen shall
be inserted into the test enclosure under no stress.
oSIST prEN 1490:2025
prEN 1490:2025 (E)
Instructions:
f) Rinse the test specimens with a clean non-chlorinated solvent (e.g. ethanol).
g) Let it dry in the air.
h) Insert the test specimens into the test enclosure along with the ammonia solution. The volume of the
container made of glass (e.g. desiccator) shall be minimum (10 ± 1) l.
i) The volume of the solution inserted shall be (200 ± 10) ml per 3 l of total volume of the container
(e.g. for a 10 l container it means (667 ± 33)
...