A heater includes a heater housing extending along a heater axis. A fuel cell stack assembly is disposed within the heater housing and includes a plurality of fuel cells which convert chemical energy from a fuel cell fuel into heat and electricity through a chemical reaction with a fuel cell oxidizing agent. A combustor disposed within the heater housing includes a combustor fuel inlet for introducing the combustor fuel into the combustor, a combustor oxidizing agent inlet for introducing a combustor oxidizing agent into the combustor, and combustor exhaust outlet for discharging a heated combustor exhaust from the combustor. An anode exhaust conduit is connected to the anode exhaust outlet and extends out of the heater housing for selectively communicating a first quantity of the anode exhaust out of the heater housing. The heater housing is heated by the fuel cell stack assembly and the heated combustor exhaust.