is in fluid communication with a first inlet 24 a of a humidifier 24 in the embodiment shown the heat exchanger 22 is a low temperature core it is understood that any conventional heat exchanger may be used such as a shell and tube heat exchanger a plate heat exchanger an air cooled heat exchanger or other heat exchanger known in the art the humidifier 24 is a water vapor transfer unit adapted to humidify an oxidant such as air prior to entering into the fuel cell stack 14 the water vapor transfer unit includes a dry side and a wet side separated by a water vapor permeable membrane not shown or the like the dry side has the first inlet 24 a and a first outlet 24 b and the wet side has a second inlet 24 c and a second outlet 24 d the first outlet 24 b is in fluid communication with a cathode inlet 14 a of the fuel cell stack 14 the second inlet 24 c is in fluid communication with a cathode outlet 14 b of the fuel cell stack 14 and the second outlet 24 d is in fluid communication with an exhaust system 30 that is in fluid communication with the atmosphere the fuel cell stack 14 includes a stack of cathodes anodes and membranes fuel cells as previously discussed herein it is understood that the number of fuel cells in the fuel cell stack.