Most heat recovery systems supplied by  in a similar way. In simple terms, the hot, humid air exiting the product via the vents is passed through an aluminium heat exchanger heating it as it passes. At the same time, incoming air is passed over the other side of the exchanger, thereby warming it up. Heat is therefore removed from the exiting moist air and is used to warm the incoming fresh air. Since the incoming air is now substantially warmer, less energy is required to heat the incoming air to the temperature required for the drying operation to continue. The whole process is not thought to influence or improve the drying process.