Patent ID: 7021553

Claim:
A space heating system comprising fuel cells for generating electrical power and heat energy from a fuel gas, an electrically regulated main valve for controlling a flow of the fuel gas to the fuel cells, a heating circuit for heating a space, the heating circuit being operable with the heat energy and including controls for regulating the heating circuit, switching for selectively supplying the electrical power from the fuel cells to a public electrical power network and to at least one of the electrically regulated main valve and the heating circuit, and for selectively supplying electric energy from the public network to at least one of the electrically regulated main valve and the heating circuit, and a controller for setting the switching to direct the electrical power from the fuel cells to the public network and to direct the electric energy from the public network to the heating circuit in a first operational mode and to direct the electrical power from the fuel cells to the electrically regulated main valve to maintain operation of the fuel cells when the electric energy from the public network fails in a second operational mode.