A heating appliance

摘要

A domestic combined heat and power system comprising a Stirling engine 1 and water heater in the form of a supplementary burner 17. The exhaust gas from the Stirling engine is used to preheat combustible gas entering the Stirling engine and subsequently used to heat the water. The water heater 15 has a helical water duct 41 towards the periphery of a housing 39. Separate parts of this duct are heated, in series, by the exhaust gas from the Stirling engine and the supplementary burner 17 firing radially outwardly through the helical duct.