This document specifies the requirements and test methods for the construction, safety, marking and rational use of energy. This standard is applicable to types B11, type C11, type C31 and type C91 appliances that burn gas and: are closed-fronted; incorporate a natural draught burner; are connected directly to an open flue or to a device to evacuate the products of combustion (open-flued appliances, balanced-flued appliances); are wall mounted, free-standing or built-in; have a nominal heat input not exceeding 20 kW (based on the net calorific value). This document is not applicable to: open fronted appliances as specified in EN 13278; decorative fuel effect appliances as specified in EN 509; catalytic combustion appliances; appliances in which the supply of combustion air and/or evacuation of products of combustion is achieved by mechanical means as specified in EN 1266; ducted-air appliances; appliances installed by means of a closure plate (see 3.3.3.3). Matters related to quality assurance systems, tests during production and to certificates of conformity of auxiliary devices are not dealt with by this standard.