DIN EN 257:2024-02

This document specifies the safety, design, construction, and performance requirements and testing for mechanical thermostats intended for use with gas appliances and similar use, hereafter referred to as "thermostats". This document is applicable to thermostats with declared maximum inlet pressures up to and including 50 kPa and of nominal connection sizes up to and including DN 50 for use with one or more fuel gases. Addition: This document is applicable to thermostats controlling the gas flow directly or indirectly through an integral gas valve. This document applies to thermostats used with gas appliances which are not installed in the open air. Thermostats dealt with in this document are intended for control functions. This document is not applicable to: a) controls which use auxiliary energy (for example, electrical energy supplied externally); b) an assessment of the control regarding Performance Level (PL) and Safety Integrity Level (SIL). The document (EN 257:2022) has been prepared by Technical Committee CEN/TC 58 "Safety and control devices for burners and appliances burning gaseous or liquid fuels", the secretariat of which is held by BSI (United Kingdom). The responsible German standardization committee is Joint Working Committee NA 041-03-10 GA "Gemeinschaftsarbeitsausschuss NHRS/NAA/NAGas: Sicherheits- und Regeleinrichtungen für wärmeerzeugende Geräte und Anlagen sowie für die Gasversorgung (SpA CEN/TC 58, WG 11, WG 13, WG 15 und ISO/TC 161, WG 3, WG 4, WG 5)" ("Joint working committee NHRS/NAA/NAGas: Safety and control devices for heating appliances and heat generating systems and for the gas distribution (SpA CEN/TC 58, WG 11, WG 13, WG 15 and ISO/TC 161, WG 3, WG 4, WG 5)") at DIN Standards Committee Heating and Ventilation Technology and their Safety (NHRS).