PURPOSE: To make cleaning work unnecessary and contribute to energy saving in restaurants where a large quantity of oil is used.

CONSTITUTION: The lower end parts of a plurality of collecting pipes 10, 10 are connected with the upper face of a lower part tank 9 and the upper end part of each of the collecting pipes 10, 10 are connected to an upper part tank 12. A bent flue 11 is installed between neighboring collecting pipes 10, 10. A heating heater 13 is installed in the lower part tank 9 and a switch 14 to shut the electricity to the heating heater 14 is set. Both the lower part and upper part tanks 9, 12 and a plurality of the collecting pipes 10, 10 are filled with a liquid-phase thermal medium. A saucer 16 is so set as to surround the lower end parts of a plurality of the collecting pipes 10, 10. Electricity is applied to the heating heater 13 to recover the oil adhering to the surface of each of the collecting pipes 10, 10 in the saucer 16 during non-business hours.