The units have replaced existing evaporators of another contractor, they that have problems of frost e performances not adequate. Hot glycol defrost foreseen in these units has shown to be a very satisfying solution for the customer both for pratical and energetic point of view. Indeed, the end user has noticed, after one month of functioning at full load, the total absence of ice both in the drip tray and in the coil, verifying the high efficiency of this type of defrost. And he has also improved the energetic efficiency of plant thanks to the thermal recovery.