Abstract: The present invention refers to an apparatus for treating and preparing food having a cooking chamber in which the food is treated and cooked. The apparatus further includes a motor-driven ventilation fan which serves to circulate the cooking chamber atmosphere, and a gas burner which serves for combusting the gas-air mixture. The cooking chamber is heated by use of a heat exchange device which includes a heat exchange pipe assembly. The heat exchange device surrounds the ventilation fan. The heat exchange pipe assembly is characterized in that at least two pipe strands are provided which extend substantially around the ventilation wheel in a continuous bordering or loop of the ventilation wheel. The subject matter of the present invention is also a heat exchange device for an apparatus of this type.

Abstract: The present invention refers to a method of detecting the moisture in an apparatus for treating and preparing food, as well as to a method of treating and preparing food. In the method according to the invention, the current temperature values and speed values of the asynchronous motor driving a gas supply and circulation mechanism are compared to at least one characteristic line which is stored in a computer, and the current moisture in the gas mixture is determined from the deviation ?N of the measured speed from the speed of the stored characteristic line. The present invention also comprises an apparatus for treating and preparing food that, in particular, serves to carry out the method of determining the moisture in a gas mixture.