Abstract The analysis of heat exchange and the efficiency of the arcs in the arc steel-melting furnaces with usual conveyor and loaded. For comparison, accepted arc furnace close in power and performance. The analysis revealed that the average efficiency of arcs furnace Consteel ASF-120co 8-9% less than particle ASF-120us. Analysis of the efficiency of the arcs of electric arc furnaces allowed to explain more 8-9% lower specific energy consumption in the furnace ASF-120co compared to the same period in the furnace ASF-120us. Calculation and the analysis of efficiency of various ways of input of heat in a bathtub of metal of ASF-120co and ASF-120us furnaces is performed. The most effective way is introduction of heat by means of electric arches which efficiency is 0,69-0,78. Heating of the metal charge by means of torches of gas-oxygen torches, efficiency of the method 0,45-0,55 is less effectively carried out. Heating of a metal bath by means of oxidation of coke which is continuously entered into slag for foaming of the last is carried out with the efficiency of a way of the method 0,28-0,36.