A heater includes a heater housing extending along a heater axis; a fuel cell stack assembly disposed within the heater housing and having a plurality of fuel cells which convert chemical energy from a fuel into heat and electricity through a chemical reaction with an oxidizing agent; an electric resistive heating element disposed within the heater housing and electrically connected to the fuel cell stack assembly; and a first thermal switch located between the fuel cell stack assembly and the electric resistive heating element. The first thermal switch is closed to place the fuel cell stack assembly in electrical communication with the electric resistive heating element when the fuel cell stack assembly is electrochemically active and is open to prevent electrical communication between the fuel cell stack assembly and the electric resistive heating element when the fuel cell stack assembly is not electrochemically active.