The most commonly used heat exchangers in hotels are volumetric heat exchangers and plate heat exchangers. The following is an introduction to the application of these two heat exchangers. The positive displacement heat exchanger is mainly used in the preparation of domestic hot water. Its product structure has the function of water storage, which can be operated under normal pressure or pressure without additional water tank. It is very suitable for the use of water supply systems in large hotels and hotels with high floors. ( The production hot water system in some bathing sauna places is similar to this, but in general, the floors of these places will not be too high. Most of them are below five floors. In this case, the mode of plate heat exchanger and floor top tank is usually selected to generate hot water for use. ) Plate heat exchanger is mainly used in hotel fan coil heating.