The fan coil unit is noisy, should these be the problems?
As one of the main supporting forms of the central air-conditioning host product, the fan coil unit is still widely used as a classic model combined with the fresh air system. Due to the advantages of convenient installation, small size, and low cost, fan coil units are widely used in hotels, office buildings, hospitals, scientific research institutions, and other places, but there are many problems with feedback noise.
At present, there are many domestic engineering units, and the strength of the design units is different. The central air-conditioning system of some smaller projects is directly installed and put into use without even being designed by the formal design unit. The noise of the fan coil unit in use is directly affected by the selection of the unit, the installation method, and the selected air duct material. Irregularities in air-conditioning system design, air-conditioning installation, and selection of air duct materials have resulted in various installation forms of fan coil units on the market, which are accompanied by high noise and affect the comfort of use.
The following is a summary and analysis of the design and selection of fan coil units, installation methods, and selection of air duct materials.

1. Noise problems caused by fan coil unit selection
On the one hand, many designers will give a certain amount of air volume margin in the design to ensure sufficient air supply and cooling capacity when designing and selecting fan coil units. Even directly select the larger unit, ignoring the noise value requirements of the unit itself, and only find out that the noise of the unit is too loud when it is used, resulting in a decrease in the comfort of use.
On the other hand, in the selection of static pressure for the air supply of the unit, a certain amount of air duct resistance margin will be given according to the design specifications. Some non-standard designs give too large a static pressure margin. Only 12Pa is enough, but a unit with a static pressure of 30Pa or even 50Pa is selected. According to the characteristics of the centrifugal fan, there is a certain transformation relationship between the static pressure of the unit and the air volume. The excessive static pressure directly leads to a large air volume during use. It follows that the noise will also become louder, which will affect comfort.

2. Analysis of the influence of installation method on the use of noise
Due to the lack of complete guidance documents on the installation of fan coil units, the experience and strength of engineering units are uneven, resulting in various installation forms of fan coil units, and many unreasonable installation methods lead to loud feedback from users.
In places with high noise requirements, it is recommended to add air ducts at the front and rear of the unit, and noise reduction measures need to be added to achieve better comfort.

3. Analysis of the influence of air duct material on the use noise of fan coil unit
During the use of the fan coil unit, although the static pressure of the unit is not large and the air duct is short, if it is not selected properly, it will directly affect the noise of the unit.
In the selection of air duct materials, where noise is required, care should be taken not to use air ducts with smooth materials such as ordinary steel plates and aluminum foil inner wall air ducts. This material not only has no sound absorption function but also reflects noise to a certain extent, resulting in more noise at the air outlet.
There are many air duct materials with noise reduction functions on the market, and suitable materials can be selected according to the use site to meet the use requirements. At present, the existing common air duct materials in the market have been counted and analyzed. For places with high noise requirements, it is recommended to choose air duct materials with a sound-absorbing function on the inner wall, which can greatly improve the comfort of use.

4. Summary
To sum up, to improve comfort and avoid unnecessary use of noise, several aspects need to be considered at the same time. For the designer, it is required to go as far as possible to the site and select the most suitable fan coil unit according to the actual needs, including accurate calculation of the required static pressure. In addition, it is also necessary to design a reasonable installation method according to the noise requirements of the place of use.
For the construction party, it is necessary to strictly abide by the construction specifications and select the appropriate air duct material.