Choosing a fan coil unit is not like choosing an air conditioner, where you can just select it based on the size of your home and room. Instead, it requires more rigorous data.

Calculation of static pressure box
① static pressure box control wind speed should not be greater than 1.5 m/S.
②the cross-sectional area of air outlet is A=G/V(G is the air supply volume), and the cross-sectional areas in all directions should be the same
③ In general system, the static pressure box can be replaced by tuyere reducing and silencer

Determination of ventilation frequency of smoke control and exhaust
① fire pump room is not less than 4 times
② 5-8 times in substation room
③ substation room 5-8 times

Layout of smoke exhaust port
① corridor more than 60 meters, do smoke outlet
② The front room of the elevator uses normally open multi-leaf air supply outlets, one for each floor
③ Self-hanging louver tuyeres are used in stairwells, and one is set on floors 2-3

Air pressure state of the room
① the air-conditioned room in the building should maintain positive pressure.
② Negative pressure should be maintained in toilets, washrooms and all kinds of equipment rooms in buildings
③ Positive pressure should be maintained in hotel rooms and negative pressure should be maintained in washrooms
④ Positive pressure should be maintained in the front hall of the restaurant, negative pressure should be maintained in the kitchen, and air pressure in the restaurant should be between the front hall and the kitchen.

Layout principle of air duct in suspended ceiling
From top to bottom: smoke exhaust duct, exhaust duct, air delivery duct and water pipe

Relative position of air supply and exhaust ports
When air supply and exhaust ducts are parallel in fan coil unit air-conditioned rooms, the air supply and exhaust outlets should not be arranged side by side as far as possible, but should be staggered

Design of air supply pipe
Try to keep the wind from going backwards in the air supply pipe to ensure good air flow and air outlet effect in the pipe

Overlapping of tee and air duct
The pipe diameter connected with the tee should be consistent with the diameter of the tee, so as to avoid excessive local loss.

These are the reasons why choosing a fan coil units take longer to build than conventional air conditioning systems.