A system configured to generate heat when supplied with a first fuel or a second fuel can include a fuel supply line operatively connected to a fuel source. A valve assembly can be operatively connected to the fuel supply line. A main burner can be operatively connected to the valve assembly. A thermoelectric generating system can be configured to transform heat to electricity. A first pilot burner can include at least one of a first thermocouple and a first Fe-ion sensor. A second pilot burner can include at least one of a second thermocouple and a second Fe-ion sensor. A printed circuit board (PCB) can be operatively connected to the valve assembly and the first and second pilot burners. The PCB can be configured to control operation of the valve assembly based on information received from at least one of the first and second pilot burners.