BAS EN 257:2004

This European Standard specifies the construction and performance requirements for mechanical thermostats for gas applications. It also establishes the definitions, test conditions and marking. It applies to mechanical thermostats controlling the gas flow directly or indirectly through an integral gas valve, and which do not require external electrical energy for their operation. The requirements of this standard apply to thermostats for all gas appliances, either heating or cooling, which are suitable for gases of one or more fuel gases of the 1st, 2nd or 3rd families and for gas pressures as defined for these gas families. This standard only applies to thermostats used with gas appliances which are not installed in the open air. Mechanical thermostats dealt with in this standard are intended for control functions.