A fuel cell stack has an air inlet manifold (21), an air turnaround manifold (22) and an air exit manifold (23); a coolant inlet is adjacent said air exit manifold; a fuel inlet manifold (16) is connected through a turnaround manifold (17) to a fuel exit manifold (18) remote from said coolant inlet. Fuel recycle is taken from the fuel manifold where the temperature is warmer than it is near the coolant inlet; recycle air for humidifying and heating inlet air is taken from the air turnaround manifold (22), and may either be recycled air provided by a recycle pump (31), or it may utilize an enthalpy recovery device (38) to transfer heat and humidity from an outflow chamber (41) to an inflow chamber (39).