This document is applicable to mechanical by wood pellets fed roomheaters, inset appliances and cookers up to 50 kW nominal heat output. The intended use of the appliances is space heating in residential buildings and can be cooking. They can be fitted with a boiler (integral part of the appliance containing water to be heated up) for the supply of hot water for central heating systems. These appliances typically use auxiliary energy which is measured in this document as well. They can be operated with either natural draught or fan-assisted combustion air. NOTE – A fan-assisted appliance does still operate under negative pressure in the flue gas system. These appliances burn wood pellets only as specified. They only operate with the firedoors closed. This document is not applicable to appliances: - with boiler intended for water systems having water temperatures above 110 °C and 3 bar; - with boiler intended for water systems having direct contact with sanitary hot water; - intended to be used with a pure horizontal exhaust (through the building wall); - with flue gas condensation in the appliance; - switching on/off for part load operation. This document specifies procedures for assessment and verification of constancy of performance (AVCP) of characteristics of mechanical by wood pellets fed roomheaters, inset appliances and cookers.