PURPOSE: To obtain a combustion apparatus for oil return type oil spray burner wherein stabilized control of fuel in quantity, unaffected by the viscosity or the pressure of the fuel, is possible by providing an oil transfer pump in the main line from a fuel tank to an oil feed pump and by controlling the oil sent to a spray nozzle in quantity through control of the number of revolutions of the oil transfer pump.

CONSTITUTION: The revolution of an oil transfer pump P, that is, the quantity of the oil sent, is controlled by signals from a control device M; an inverter 16 converts the signals. The load in a combustion chamber 2 is measured by a load-meter 19 and changes in load detected thereby are converted to signals by a controller 20 and then sent to the control device M. The suction pressure of an oil feed pump 4 is regulated to a constant pressure without being influenced by the delivery pressure of the oil transfer pump P. When the quantity of the oil sent is increased, a pressure-reducing valve 11 acts toward closure so as to keep the suction pressure of the oil feed pump 4 constant; a decrease in the return quantity, an increase in the return pressure in the return line 7, and an increase in the quantity of the spray from a spray nozzle 1 result. The pressure balancing at each point at this time, when the viscosity is constant, is always perfectly linked with the quantity of the oil sent. Therefore, the pressure balancing is altered with changes in viscosity but the quantity of the oil spray agrees with the quantity of the oil sent without being affected by changes in viscosity.