A fuel heating system for use with a combined cycle gas turbine including a turbine outlet configured to channel a flow of exhaust gas towards a heat recovery steam generator is provided. The system includes a heat exchanger configured to channel a flow of fuel therethrough, and a plurality of heat transfer devices that each include an evaporator portion in thermal communication with the flow of exhaust gas and a condenser portion selectively thermally exposed to the flow of fuel. Each of the plurality of heat transfer devices are configured to conduct different grade heat from the exhaust gas to regulate a temperature of the fuel.