Working principle fan coil units are: fan unit constantly circulating air within the room where to keep them through the supply of cold water or hot water coil, continue to be cooled or heated to maintain the temperature of the room. Among them, the role of the air filter is to filter indoor air circulating dust, improve health conditions of the room, while protecting the coil does not become clogged with dust, ensure air flow and heat transfer. The main advantage of fan coil air conditioning system are: less noise, suitable for hotel rooms; with individual control of superiority; regulation and control system partition easily; small fan coil itself, size, layout and installation more convenient. The main disadvantage of fan coil air conditioning system is: As the unit set up in the room, and the building and other trades needed for effective cooperation; relative dispersion unit, its large maintenance workload; must solve the problem of fresh air; small fan static pressure You can not use a high-performance filter, making the indoor air cleanliness is not high.