Coil cooling capacity insufficiency: The problem is currently mostly complained by users. The main reason for this problem is that many enterprises do not have their own the test means in order to reduce the fan coil unit cost price; the parameters on samples are copied from the other manufacturers' samples, and thermal performance of coil produced by them is bad. (This is mainly caused by the fins form, expanding quality, production process). Therefore, it is recommended that you should pay attention to test facilities and means of the manufacturers during the project inspection; it is difficult to imagine the manufacturers without their own test device can produce a good product.
Air volume:
Currently we calculate cooling load and select fan coil through access to relevant manufacturers when carrying out specific engineering design. How to consider the amount of coil wind is a problem. The coil of the majority of manufacturers in the domestic market is only available for a threw-row tube, but there are also two-row coil provided by manufacturers. For most civil air-conditioning systems, it is more beneficial to select the second row tube coils (exception for high humidity occasions). This is because the two-row pipe products have larger air volume under the same cooling capacity, which will increase air changes in the air-conditioned room, help to improve packaged air conditioner precision and comfort. With the same cooling capacity, the use of small temperature difference, large amount of wind to blast will have better air conditioning effect than the large temperature difference, the small amount of wind blast.
Noise problem: This is a large gap between domestic products and foreign products, and is one of the points why currently the coil is complained due to quality problems. The cause of this problem is that the motor and fan coil configuration and matching is unreasonable. Another reason is that manufacturer’s quality management is not strict, assembly workers don’t have strong sense of responsibility, resulting in an unstable product quality. So when we look at manufacturers products, we should inspect the noise test report of the product (note that it must be that we are ready to order several products) issued by the authority of the state quality inspection departments. On-site sampling for the projects with large volume selection, and send to the relevant quality inspection departments for test.
The residual pressure outside the machine: Because tests of our current national standards for fan coil air volume, cold and noise parameter are carried out under 0 external static pressure conditions. But in actual use, the coil outlet tend to pick a short duct and a louver, some works also equip with return air box, so we will find the coil actual amount of wind is less than its name amount of wind in actual use, the consequence is the room air volume decreases, the supply air temperature difference increases, the air-conditioning comfort declines. To avoid this situation, some designers select according to the mid-range air volume of the coil in the selection, in order to avoid the lack of air volume, but increasing the initial investment for the project. Therefore, it is recommended that in the case of the selection of the domestic testing standards not yet changed, we should give priority to select units with residual pressure (generally 10 ~ 15Pa).
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