FUEL CELL SYSTEM, AND METHOD OF ITS OPERATION

In a fuel cell system, for example HTPEM fuel cells. a valve system is employed by selectively guiding exhaust gas from the burner either to the reformer for heating the reformer, especially during normal operation, or to by-pass the reformer in startup situations in order to heat the fuel cell stack before starting heating the reformer. Optionally, a compact burner/reformer unit is provided.