The main control parameters of horizontal concealed fan coil unit are rated air volume, outlet static pressure, input power, rated cooling capacity, rated heat supply, noise, water resistance, etc. For the fan coil unit of double-pipe water system (suitable for air conditioning system that only converts heating or cooling according to season or air conditioning area), only one set of coil units are configured, and both heating and cooling in winter and summer are equipped, for fan coil units of four-pipe water system (applicable to air conditioning systems with frequent heating/cooling conversion), a combined type of heating and cooling coils shall be configured.

Selection of methods.
1. The main control parameters of the unit are rated air volume, outlet static pressure, input power, rated cooling capacity, rated heat supply, noise, water resistance, etc.
2. The air supply volume of the fan coil unit is about 340~2380 m/h, and the outlet static pressure is less than 100Pa (the outlet static pressure is greater than 30Pa for high static pressure type).
3. The selection of unit specifications should be determined by factors such as room cold, heat load and air fan coil heat and humidity ratio:.
1) When the fresh air is equal to the room air parameters, the fan coil unit only bears the cold and heat load generated by the enclosure structure and the room.
2) When the fresh air enthalpy value is greater than or less than the room air enthalpy value, the fan coil unit should add or deduct part of the fresh air cooling and heat load.
3) When the absolute moisture content of the fresh air is lower than the moisture content of the room air, and the wet load of the room can be fully borne, the fan coil can only bear the sensible heat load of the room, which should be configured according to the dry working condition.
4) When the sensible heat load of the room occupies a large proportion, the air volume of the fan coil unit should be checked through the calculation of the sensible heat balance.
5. When selecting the unit, the deviation between the actual performance and the rated value should be considered, and the following characteristics should be paid attention:.
1) The rated cooling capacity of the unit is generally the test value under the condition that the air enthalpy drop value is equal to 15.9kJ/kg.
2) The rated heat supply of single coil unit is generally 1.5 times of the rated cooling capacity.
3) The rated value of each fan coil item parameter is the value of the fan at the high speed, and it is generally appropriate to select the value according to the mid-range wind speed of the product sample during design.
6. For the fan coil unit of the double-pipe water system (applicable to the air conditioning system with heating or cooling conversion only according to the season or only according to the air conditioning area), only one set of coil units shall be configured. For the fan coil unit of the four-pipe water system (applicable to the air conditioning system with frequent heating/cooling conversion), a combined type of heating and cooling two sets of coil units shall be configured.
7. For low temperature, cold storage air conditioning system, large temperature difference unit should be selected.
8. At present, fan coil units have the following control types:.
1) With a three-speed selector switch, it can be switched between winter and summer, and the water circuit electric valve is linked by the room temperature controller to implement automatic control.
2) With a three-speed selector switch, it can be switched between winter and summer, and the fan can be started and stopped by the room temperature controller to implement semi-automatic control.
3) Only with a three-speed selector switch, the fan coil is manually controlled.
4) Stepless speed regulation control of the fan.
According to the requirements of relevant energy-saving standards, the control mode of electric temperature control valve and third speed wind speed combination should be adopted.
9. When selecting products, attention should be paid to the three problems of noise, condensation and the quality of the matching motor. This is the project with more quality problems in the current sampling inspection.
10. The marking methods of fan coiling units at home and abroad are different, and the design and selection should be paid attention to and distinguished.

Fan coil control principle and wiring.
Fan coil control mostly adopts local control scheme, which is divided into simple control and temperature control:
Fan coil simple control: the use of three-speed switch direct manual control fan three-speed conversion and start and stop.
Fan coil temperature control: the thermostat is used to automatically control the opening and closing of the electric two/three-way valve, the three-speed conversion of the fan, or directly control the three-speed conversion and start-stop of the fan according to the comparison between the set temperature and the actual detected temperature, so as to achieve a constant temperature by controlling the water flow or air volume of the system.
Shandong Xingheng Environmental Technology Group Co., Ltd. is located in Luquantun Development Zone, Dezhou, Shandong Province, the hometown of glass fiber reinforced plastic in China. The company has three-level qualification for construction mechanical and electrical installation engineering, three-level qualification for environmental protection engineering, and safety production license. It is the first in the industry to pass ISO9001 quality management system certification, ISO14001 environmental management system certification, OHSAS18001 occupational health management system certification, an axial fan invention patent, a fan utility model patent, EIA, three at the same time waiting for complete procedures