Several problems that should be paid attention to when selecting fan coil
China has the following items in the fan coil detection indicators: air volume, cooling capacity, heat supply, unit fan power cooling capacity, water resistance, A-level noise, condensation, condensation water treatment, motor winding temperature rise, Thermal insulation resistance, leakage current, ground resistance, etc. However, the main criteria for evaluating the quality of a fan coil in a project are the air volume, cooling capacity, noise, and power consumption.
(1) Insufficient cooling capacity of coil
This problem is currently the most complained by users. The main reason for this problem is that many companies do not have their own testing methods, the parameters on the samples are copied from the samples of other manufacturers, and the thermal performance of the coils produced by themselves is poor (this is mainly caused by the fin form , Quality of the expanded tube, production process, etc.). Therefore, it is recommended to pay attention to the test facilities and methods of the manufacturer during the project inspection. It is difficult to imagine that a manufacturer without its own test device can produce good products.
(2) Air volume
At present, in the specific engineering design, we often choose the fan coil according to the calculated cooling load by consulting the samples of the relevant manufacturers. How to consider the air volume of the coil is a problem. Most manufacturers in the domestic market have only one type of three-row coil, but some manufacturers provide two-row coils.
The author believes that for most civil building air-conditioning systems, it is more advantageous to choose a two-row tube coil (except for high humidity occasions). This is because the product of the second row of tubes has a larger air volume under the same cooling capacity, which will increase the number of air changes in the air-conditioned room and help improve the accuracy and comfort of the air-conditioning. Under the same cooling capacity, the use of small temperature difference and large air volume air supply will achieve better air conditioning effects than large temperature difference and small air volume air supply.
(3) Outside pressure
Because the current national standard of coils in our country stipulates that the testing of the air volume, cooling capacity and noise of fan coils is carried out under the condition that the external static pressure of the machine is 0. However, in actual use, a small section of air duct and air outlet louver are often connected before the air outlet of the coil. In some projects, there is also a return air box. Therefore, in actual use, the actual air volume of the coil will be less than its nominal air volume The consequence of this is that the air volume in the room decreases, the temperature difference between the supply air increases, and the comfort of the air conditioner decreases.
In order to avoid this situation, some designers choose according to the mid-range air volume of the coil when selecting the model to avoid insufficient air volume, but increase the initial investment of the project. Therefore, the author recommends that when the domestic test standards have not changed, we should prefer to select the unit with residual pressure (generally 10 ~ 15Pa) when selecting the coil.
(4) Noise problem
This is a place where there is a large gap between domestic products and foreign products, and it is also an important point for coil coils to be complained about due to quality problems. Most of the reasons for this problem are the unreasonable configuration and matching of the motor and fan in the coil. Another reason is that the manufacturer's quality control is not strict, and the assembler's sense of responsibility is not strong, resulting in unstable product quality. Therefore, when we inspect a manufacturer ’s products, we should consult the noise test report of the product issued by the national authoritative quality inspection department (note that it must be the products we are planning to order). For large-scale engineering projects, sampling should be sent to relevant quality inspection departments for testing.
