Known as the start of refrigerators in history, the greatest reason of preferring this system in hotels is that it offers completely silent and vibration-free operation. In this method, which is based on heating the liquid cooler that is a mixture of ammonia and water with a heating coil, no sound or vibration is generated since no mechanical equipment is used. Since the cooling gas needs to stay hot always, the heating coil continues operating during the most part of the day.

This silent small cooler, which is economical due to its low cooling capacity since it has no compressor, operates by activation of ammonia gas that is heated with a small heating coil. Where to use such fridges with low cooling capacity: Since they silent and cost-efficient, they are preferred in areas where there is no constant movement such as hotel guestrooms. Since guestrooms are generally unoccupied until the evening, the fridge operates during that time and cools the products inside it. When the guests enter their room, they may take the cool drink from the fridge and enjoy it. This small cooler, which offers less cooling capacity when compared to compressor models, may be used to store breakfast food or to cool bottles if the cooler will not be used for a long time. Whereas the fridge offers less cooling capacity, it runs on a little electricity, provides energy-efficiency and silent operation.