Dual-fuel burners are of fan-assisted or forced-draught type and incorporate the features of both natural gas & oil burners necessary for the safe and efficient combustion of either fuel. The burner mechanisms and their control are able to achieve the correct fuel/air ratios for firing with either fuel and at any firing rate that the burner is capable of. Dual fuel burners are configured with an oil nozzle down the center of and concentric with the gas nozzle. These burners are designed to operate typically on either gaseous or liquid fuels. They are used for economic reasons, where the customer need to switch between a gaseous fuel like natural gas and a liquid fuel like oil. These burners operate on one fuel or the other and sometimes on the fuels simultaneously. Dual-fuel burners efficiently fire gas or any grade of light or heavy oil with quick changeover.