The inventive method relates to a conversion, in an extremely simple manner, of a heating system for heating oil to renewable liquid fuels, for example, purified raw glycerin, during which the burner is refitted with pulsed injectors, the heating chamber being provided with an evaporator chamber made of sintered material or fiber metal. The burner is heated by contact heat from the evaporator chamber. The burner is switched to a partial load and start-up operation via computers. The flue is converted to a flue having a concentric waste gas pipe including water separation and a purifying filter, and the tank is filled with a protective gas. The heated injectors are also used for introducing additives, reagents or catalysts into reactor chambers, e.g. during the production of hydrogen. The targeted heating of the injector nozzle leads to the increase in the heat content in propellant or fuel to an optimal combustion or reaction. The inventive method also involves: heating and increasing the pressure of the fuel; adding additives that lower the flash point; regulating the quantity of fuel by a proportional valve or pulsed injector, and; purifying the fuels by using a high-pressure filter. An anti-swirl device is employed during the supply of combustion air.