Problems simulating combustion furnace that works with forced covection

Hi, I have this oven model which I am going to simulate the conditions at which it works, according to the information that I have the oven must reach a temperature of 473 K, I have the speed of the rotor that is coupled to the fan is 1700rpm that is to say about 180 rad and according to measurements the temperature of the burner is in the range of 500K. In the simulation, what I do is put a heat source that emits a temperature of 500 K by selecting a fan that has the library with characteristics similar to the one I have in mind at rotor speed, I point points on the bottom face , front, at the door and near the fan so that the simulation ends when at any of those points the expected temperature is reached the results that are being iterated are not adequate as I show below.

Another way I propose is to put an ambient pressure on the upper part of the chamber, a volumetric flow inlet in the part of what looks like a chimney and an outlet in a small hole in the upper part of the chamber as a boundary condition el flujo de entrada lo pongo en  0,1175 m3/s y el de salida 0,0041 

Any recommendations to find a solution in the way of approaching the model?

SolidworksFlow Simulation