In a refuse incinerator, a relay feedback controller is equipped to keep the vapor flow rate in a neighborhood of a constant value. Bifurcations and chaotic phenomena are observed under this control system. In this paper, numerical simulations are carried out using a model of the refuse combustion control system. It is confirmed that these phenomena are caused not by the characteristic of the refuse combustion, but by the structure of the control system that adjusts a rectangular input by the on-off signal of the relay with a hysteresis. In this system, the value of the vapor production rate has a maximum value when the system is a one-periodic state: However, it is also shown that the value is fairly high in some cases even if the system is chaotic.