When designing central air conditioning, consideration should be given to winter antifreeze issues. It is recommended to use hot water for antifreeze measures, and steam and electric heating are not supported. Steam antifreeze can also be used, but it is prone to uneven temperature. The upper part of the horizontal concealed fan coil has a relatively high temperature, and the bottom has already started to freeze. Electric heating is also not supported for use. Firstly, electric heating is prone to danger, and secondly, it consumes more electricity and is not energy-efficient. In terms of control, attention should also be paid to not installing a single horizontal concealed fan coil switch, and it should be fully controlled.
        If the horizontal concealed fan coil unit is not used in winter, it is recommended to: drain all the water inside the horizontal concealed fan coil unit, b. add blind plates to the water supply and return, c. use compressed air to blow (the duration of compressed air blowing depends on the size of the horizontal concealed fan coil unit), d. add antifreeze to the horizontal concealed fan coil unit, which does not necessarily need to be filled up, but must ensure that the liquid in the horizontal concealed fan coil unit is fully diluted by the antifreeze. If the system is shut down in winter but there is a heat source, the heat source can be switched to the horizontal concealed fan coil water system to operate the small circulation pump.
        Without a heat source, an electric heater (shell and tube type parallel to the water system) can be installed in combination with a small circulation pump to ensure that the water temperature in the horizontal concealed fan coil water system pipe is not lower than 5 ℃ and does not freeze. To ensure that the water in the system is maintained at 5 ℃, the electric heating power is not too high, and the operating cost is not high, which is more reliable than methods such as draining water and adding antifreeze.