Metallurgy, as one of the oldest industries, is currently experiencing a technological boom in an effort to increase production efficiency with the least possible impact on the environment. Modeling methods make it possible to design and simulate a technological process or technological equipment for conditions that take into account the above-mentioned aspects. For this reason, the article focuses on the use of simulation modeling using accessible computer technologies in order to improve the operation of heating aggregates with the metal-bearing batch, such as a continuous heating furnace. The paper describes the methodology for modeling the flow of flue gases in the working space of a gas heating furnace, which results in their enthalpy representation. A simulation study was performed for a gas-fired furnace used to heat gates. Three case studies were simulated with set values of on and off burners and fuel flow to them. The effect of these parameters on the total amount of recirculated flue gas was investigated. The results showed that the fuel flow regulation to the burners at the material inlet into the furnace had a higher effect on the overall recirculation than the switching on and off the burners on the furnace's outlet side. The results pointed to critical points on the inner shell of the furnace, which could be the most critically thermally stressed, for example, in the places of the collision of opposing flue gas flows.