Heater and method of operating

A method of operating a heater having 1) a heater housing having a space and extending along a heater axis;

• 2) a fuel cell stack assembly disposed within said 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, said fuel cell stack assembly having a) a fuel inlet for introducing said fuel to a plurality of anodes of said plurality of fuel cells, b) an oxidizing agent inlet for introducing said oxidizing agent to a plurality of cathodes of said plurality of fuel cells, c) an anode exhaust outlet for discharging an anode exhaust from said plurality of fuel cells, and d) a cathode exhaust outlet for discharging a cathode exhaust from said plurality of fuel cells;
• and 3) a combustor disposed within said space of said heater housing in fluid communication with said anode exhaust outlet and said cathode exhaust outlet;
• said method comprising:
• using said fuel cell stack assembly to produce said anode exhaust and said cathode exhaust;
• communicating said anode exhaust and said cathode exhaust to said combustor;
• using said combustor to combust said anode exhaust and said cathode exhaust to produce a heated combustor exhaust which is discharged directly into said space of said heater housing;
• and
• heating said heater housing with said fuel cell stack assembly and with said heated combustor exhaust.