Abstract: A gas fired infrared heater is provided that includes a burner, a combustion chamber, a cooling air passage for supplying cooling air to the combustion chamber, a combustion air passage for supplying combustion air to the burner; and an outlet passage allowing combustion product gases to exit the combustion chamber. The cooling air passage is separate from the combustion air passage. The cooling air passage and the combustion air passage both draw from the same pressure zone into which combustion products exit.