System with integrated fuel cells and heat exchanger

Part of thermal energy as hot waste gases is transferred in a heat exchanger (1) onto a liquid heat-carrying medium like water or oil, which carries heat for room heating and/or for heating up water for domestic/industrial use. First (12) and second (13) separate channels fit in a heat exchanger inside a double-walled jacket (10) for waste gases from fuel cells and a supplementary burner. An independent claim is also included for an installation with a heat exchanger.