The regulated gas mixed with injected air generates blue flames that make the oven to reach setup temperature in the short time. After reaching the desired temperature, the burners do not have to work all the time and gas is consumed only several seconds to offset heating loss. Furthermore, because the oven is installed with compact low-thermal-conductivity insulation and precise digital temperature controller, heat retention of the oven is excellent and over-heating is greatly eliminated. These distinguishing features greatly reduce unnecessary energy wasting, saving money for the owner.