A heater can be configured to operate with either a first fuel at a first pressure or a second fuel at a second pressure and can include an elongated tubular combustion chamber, a first combustion chamber nozzle outlet, a second combuston chamber nozzel outley, and a fluid flow controller. In some embodiments, the fluid flow controller is configured to direct the first fuel to the first combustion chamber nozzle outlet and then to the second combustion chamber nozzle ourlet when the controller is in a first position. In a second position, the fluid flow controller is configured to direct the second fuel to the second combustion chamber nozzle outlet.