Fan coil unit can meet the indoor air environment required by process production. The temperature and humidity conditions not only directly affect the normal production process, but also affect the output and quality of products. Such as textile production, precision instrument production and pharmaceutical production technology. It can also eliminate indoor harmful gas and heat and humidity. The carbon dioxide in comfortable air-conditioned room and the bad smell in toilet. The toxic, odorous and other harmful gases produced by the production workshop of process air conditioning, as well as the local parts that emit a lot of heat and moisture, fan coil units need channel air conditioning and exhaust facilities to eliminate, so as to obtain a good indoor air environment.