EN 257:2010

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 Units of measurement and test conditions
6 Construction requirements
7 Performance
8 EMC/Electrical requirements
9 Marking, installation and operating instructions
Annex A (informative) - Gas connections in common use in
        the various countries
Annex B (informative) - Leak-tightness test - volumetric
        method
Annex C (informative) - Leak-tightness test - pressure loss
        method
Annex D (normative) - Conversion of pressure loss into
        leakage rate
Annex E (normative) - Electrical/electronic component
        fault modes
Annex F (normative) - Additional requirements for safety
        accessories and pressure accessories as defined in
        EU Directive 97/23/EC
Annex G (normative) - Materials for pressurized parts
Annex H (informative) - Additional materials for pressurized
        parts
Annex I (normative) - Requirements for controls used in DC
        supplied gas burners and gas burning appliances
Annex ZA (informative) - Relationship between this European
         Standard and the Essential Requirements of EU
         Directive 2009/142/EC relating to appliances
         burning gaseous fuels
Bibliography

This European Standard specifies the safety, construction and performance requirements for mechanical thermostats intended for use with gas appliances and similar use, hereafter referred to as ‘thermostats’.This European Standard applies to thermostats with declared maximum inlet pressures up to and including 50 kPa (500 mbar) of nominal connection sizes up to and including DN 50 for use with one or more fuel gases in accordance with EN 437.This European Standard applies to thermostats controlling the gas flow directly or indirectly through an integral gas valve, and which do not require external electrical energy for their operation.This European Standard only applies to thermostats used with gas appliances which are not installed in the open air.Thermostats dealt with in this European Standard are intended for control functions.