Fuel cell heating appliances are combined heat and power plants (CHP) which use a fuel cell to generate electrical energy. The present guideline will restrict itself to domestic heating applications in buildings where the FCHA consumes up to 70 kWth (with respect to the net caloric value Hi). In addition to the purchase order for the complete FCHA, an independent definition of its scope will be necessary. The service contract will be linked to this definition since the service contract may have a different scope to that of the sales contract. This document will be effective after completion of commissioning of the FCHA.