The project is applicable to non-mechanically fired appliances whose primary function is to provide heat into the space in which they are installed and which are listed under categories 1a and 2a of table 1 of prEN 13240. Additionally, where fitted with a boiler, they also provide domestic hot water and/or central heating. These appliances may burn naturally occurring or manufactured solid mineral fuels, peat briquettes, natural or manufactured wood logs and biomass based products which are in the form of an identifiable consistent product.