Last Updated on December 23, 2022 by Shawn Lee
The fan is divided into two pipes, three pipes, and four pipes according to the quantity of water system layout, which refers to the form of the water system in each building.
Two fan coil unit : the whole building water system adopts a water inlet pipe and a water outlet pipe. This system is supplied with cold water in summer and hot water in winter. Such a system can bring warmth to the whole area in cold winter and coolness in hot summer.

Four control fan coil unit : inside the fan coil, there are two surface coolers, and each group of surface coolers is connected to a water inlet pipe and a water outlet pipe.
From the appearance, we can see that the fan coil has two inlet pipes and two outlet pipes. Fan coil units with this structure are mostly used in hospitals, hotels, and other places with high environmental requirements.
Four-control fan coil units can adjust the indoor temperature at will and can send out cold air to reduce the indoor temperature or hot air to increase the indoor temperature according to the needs of indoor personnel.
Comparison of two-control fan coils and four-control fan coils;
Two-control fan coil units: the operation and management are relatively simple, the construction is convenient, and the construction cost is saved, but the cooling or heating function modes cannot be switched. Only cold air or hot air can be provided.
Four-control fan coil units: the operation and management are relatively complicated, the construction is complicated, and the construction cost is high. However, indoor users have more choices, and they can arbitrarily switch the hot and cold modes to adjust and change the indoor temperature environment according to their individual needs.

What environment is suitable for two controls? What building environment is suitable for four controls?
When the air-conditioning system running throughout the year only requires the conversion of cooling and heating according to the season, two control water systems should be adopted.
High-rise buildings, especially high-rise shopping malls, amusement parks, and cinemas, are large-scale construction sites with relatively dense personnel. Two control systems can meet the requirements of most indoor temperature regulation, and air-conditioning water system is widely used in multi-story or high-rise civil buildings.
During the whole year’s operation, the air-conditioning system with a four-pipe water system should be used when the cooling and heating conditions frequently alternate or need to be used simultaneously. Four-control fan coil unit is suitable for the situation where the standard of the construction site is high and the budget is met.